Publications

Abstract

Language is inherently multimodal. In spoken languages, combined spoken and visual signals (e.g., co-speech gestures) are an integral part of linguistic structure and language representation. This requires an extension of the parallel architecture, which needs to include the visual signals concomitant to speech. We present the evidence for the multimodality of language. In addition, we propose that distributional semantics might provide a format for integrating speech and co-speech gestures in a common semantic representation.

Abstract

When learning a spoken second language (L2), words overlapping in form and meaning with one’s native language (L1) help break into the new language. When non-signing speakers learn a sign language as L2, such forms are absent because of the modality differences (L1:speech, L2:sign). In such cases, non-signing speakers might use iconic form-meaning mappings in signs or their own gestural experience as gateways into the to-be-acquired sign language. Here, we investigated how both these factors may contribute jointly to the acquisition of sign language vocabulary by hearing non-signers. Participants were presented with three types of sign in NGT (Sign Language of the Netherlands): arbitrary signs, iconic signs with high or low gesture overlap. Signs that were both iconic and highly overlapping with gestures boosted learning most at first exposure, and this effect remained the day after. Findings highlight the influence of modality-specific factors supporting the acquisition of a signed lexicon.

Abstract

The present study investigated to what extent children, compared to adults, benefit from gestures to disambiguate degraded speech by manipulating speech signals and manual modality. Dutch-speaking adults (N = 20) and 6- and 7-year-old children (N = 15) were presented with a series of video clips in which an actor produced a Dutch action verb with or without an accompanying iconic gesture. Participants were then asked to repeat what they had heard. The speech signal was either clear or altered into 4- or 8-band noise-vocoded speech. Children had more difficulty than adults in disambiguating degraded speech in the speech-only condition. However, when presented with both speech and gestures, children reached a comparable level of accuracy to that of adults in the degraded-speech-only condition. Furthermore, for adults, the enhancement of gestures was greater in the 4-band condition than in the 8-band condition, whereas children showed the opposite pattern. Gestures help children to disambiguate degraded speech, but children need more phonological information than adults to benefit from use of gestures. Children’s multimodal language integration needs to further develop to adapt flexibly to challenging situations such as degraded speech, as tested in our study, or instances where speech is heard with environmental noise or through a face mask.

Abstract

Prior work with hearing children acquiring a spoken language as their first language shows that spatial language and cognition are related systems and spatial language use predicts spatial memory. Here, we further investigate the extent of this relationship in signing deaf children and adults and ask if late sign language exposure, as well as the frequency and the type of spatial language use that might be affected by late exposure, modulate subsequent memory for spatial relations. To do so, we compared spatial language and memory of 8-year-old late-signing children (after 2 years of exposure to a sign language at the school for the deaf) and late-signing adults to their native-signing counterparts. We elicited picture descriptions of Left-Right relations in Turkish Sign Language (Türk İşaret Dili) and measured the subsequent recognition memory accuracy of the described pictures. Results showed that late-signing adults and children were similar to their native-signing counterparts in how often they encoded the spatial relation. However, late-signing adults but not children differed from their native-signing counterparts in the type of spatial language they used. However, neither late sign language exposure nor the frequency and type of spatial language use modulated spatial memory accuracy. Therefore, even though late language exposure seems to influence the type of spatial language use, this does not predict subsequent memory for spatial relations. We discuss the implications of these findings based on the theories concerning the correspondence between spatial language and cognition as related or rather independent systems.

Abstract

The human experience is shaped by information from different perceptual channels, but it is still debated whether and how differential experience influences language use. To address this, we compared congenitally blind, blindfolded, and sighted people's descriptions of the same motion events experienced auditorily by all participants (i.e., via sound alone) and conveyed in speech and gesture. Comparison of blind and sighted participants to blindfolded participants helped us disentangle the effects of a lifetime experience of being blind versus the task-specific effects of experiencing a motion event by sound alone. Compared to sighted people, blind people's speech focused more on path and less on manner of motion, and encoded paths in a more segmented fashion using more landmarks and path verbs. Gestures followed the speech, such that blind people pointed to landmarks more and depicted manner less than sighted people. This suggests that visual experience affects how people express spatial events in the multimodal language and that blindness may enhance sensitivity to paths of motion due to changes in event construal. These findings have implications for the claims that language processes are deeply rooted in our sensory experiences.

Abstract

Each sensory modality has different affordances: vision has higher spatial acuity than audition, whereas audition has better temporal acuity. This may have consequences for the encoding of events and its subsequent multimodal language production—an issue that has received relatively little attention to date. In this study, we compared motion events presented as audio-only, visual-only, or multimodal (visual + audio) input and measured speech and co-speech gesture depicting path and manner of motion in Turkish. Input modality affected speech production. Speakers with audio-only input produced more path descriptions and fewer manner descriptions in speech compared to speakers who received visual input. In contrast, the type and frequency of gestures did not change across conditions. Path-only gestures dominated throughout. Our results suggest that while speech is more susceptible to auditory vs. visual input in encoding aspects of motion events, gesture is less sensitive to such differences.

Abstract

We investigated cross-modal influences between speech and sign in hearing bimodal bilinguals, proficient in a spoken and a sign language, and its consequences on visual attention during message preparation using eye-tracking. We focused on spatial expressions in which sign languages, unlike spoken languages, have a modality-driven preference to mention grounds (big objects) prior to figures (smaller objects). We compared hearing bimodal bilinguals’ spatial expressions and visual attention in Dutch and Dutch Sign Language (N = 18) to those of their hearing non-signing (N = 20) and deaf signing peers (N = 18). In speech, hearing bimodal bilinguals expressed more ground-first descriptions and fixated grounds more than hearing non-signers, showing influence from sign. In sign, they used as many ground-first descriptions as deaf signers and fixated grounds equally often, demonstrating no influence from speech. Cross-linguistic influence of word order preference and visual attention in hearing bimodal bilinguals appears to be one-directional modulated by modality-driven differences.

Abstract

Gestures help speakers and listeners during communication and thinking, particularly for visual-spatial information. Speakers tend to use gestures to complement the accompanying spoken deictic constructions, such as demonstratives, when communicating spatial information (e.g., saying “The candle is here” and gesturing to the right side to express that the candle is on the speaker's right). Visual information conveyed by gestures enhances listeners’ comprehension. Whether and how listeners allocate overt visual attention to gestures in different speech contexts is mostly unknown. We asked if (a) listeners gazed at gestures more when they complement demonstratives in speech (“here”) compared to when they express redundant information to speech (e.g., “right”) and (b) gazing at gestures related to listeners’ information uptake from those gestures. We demonstrated that listeners fixated gestures more when they expressed complementary than redundant information in the accompanying speech. Moreover, overt visual attention to gestures did not predict listeners’ comprehension. These results suggest that the heightened communicative value of gestures as signaled by external cues, such as demonstratives, guides listeners’ visual attention to gestures. However, overt visual attention does not seem to be necessary to extract the cued information from the multimodal message.

Abstract

How people communicate about motion events and how this is shaped by language typology are mostly studied with a focus on linguistic encoding in speech. Yet, human communication typically involves an interactional exchange of multimodal signals, such as hand gestures that have different affordances for representing event components. Here, we review recent empirical evidence on multimodal encoding of motion in speech and gesture to gain a deeper understanding of whether and how language typology shapes linguistic expressions in different modalities, and how this changes across different sensory modalities of input and interacts with other aspects of cognition. Empirical evidence strongly suggests that Talmy’s typology of event integration predicts multimodal event descriptions in speech and gesture and visual attention to event components prior to producing these descriptions. Furthermore, variability within the event itself, such as type and modality of stimuli, may override the influence of language typology, especially for expression of manner.

Abstract

We present a dataset of behavioural and fMRI observations acquired in the context of humans involved in multimodal referential communication. The dataset contains audio/video and motion-tracking recordings of face-to-face, task-based communicative interactions in Dutch, as well as behavioural and neural correlates of participants’ representations of dialogue referents. Seventy-one pairs of unacquainted participants performed two interleaved interactional tasks in which they described and located 16 novel geometrical objects (i.e., Fribbles) yielding spontaneous interactions of about one hour. We share high-quality video (from three cameras), audio (from head-mounted microphones), and motion-tracking (Kinect) data, as well as speech transcripts of the interactions. Before and after engaging in the face-to-face communicative interactions, participants’ individual representations of the 16 Fribbles were estimated. Behaviourally, participants provided a written description (one to three words) for each Fribble and positioned them along 29 independent conceptual dimensions (e.g., rounded, human, audible). Neurally, fMRI signal evoked by each Fribble was measured during a one-back working-memory task. To enable functional hyperalignment across participants, the dataset also includes fMRI measurements obtained during visual presentation of eight animated movies (35 minutes total). We present analyses for the various types of data demonstrating their quality and consistency with earlier research. Besides high-resolution multimodal interactional data, this dataset includes different correlates of communicative referents, obtained before and after face-to-face dialogue, allowing for novel investigations into the relation between communicative behaviours and the representational space shared by communicators. This unique combination of data can be used for research in neuroscience, psychology, linguistics, and beyond.

Abstract

Expressing Left-Right relations is challenging for speaking-children. Yet, this challenge was absent for signing-children, possibly due to iconicity in the visual-spatial modality of expression. We investigate whether there is also a modality advantage when speaking-children’s co-speech gestures are considered. Eight-year-old child and adult hearing monolingual Turkish speakers and deaf signers of Turkish-Sign-Language described pictures of objects in various spatial relations. Descriptions were coded for informativeness in speech, sign, and speech-gesture combinations for encoding Left-Right relations. The use of co-speech gestures increased the informativeness of speakers’ spatial expressions compared to speech-only. This pattern was more prominent for children than adults. However, signing-adults and children were more informative than child and adult speakers even when co-speech gestures were considered. Thus, both speaking- and signing-children benefit from iconic expressions in visual modality. Finally, in each modality, children were less informative than adults, pointing to the challenge of this spatial domain in development.

Abstract

How does communicative efficiency shape language use? We approach this question by studying it at the level of the dyad, and in terms of multimodal utterances. We investigate whether and how people minimize their joint speech and gesture efforts in face-to-face interactions, using linguistic and kinematic analyses. We zoom in on other-initiated repair—a conversational microcosm where people coordinate their utterances to solve problems with perceiving or understanding. We find that efforts in the spoken and gestural modalities are wielded in parallel across repair turns of different types, and that people repair conversational problems in the most cost-efficient way possible, minimizing the joint multimodal effort for the dyad as a whole. These results are in line with the principle of least collaborative effort in speech and with the reduction of joint costs in non-linguistic joint actions. The results extend our understanding of those coefficiency principles by revealing that they pertain to multimodal utterance design.

Abstract

When people establish shared symbols for novel objects or concepts, they have been shown to rely on the use of multiple communicative modalities as well as on alignment (i.e., cross-participant repetition of communicative behavior). Yet these interactional resources have rarely been studied together, so little is known about if and how people combine multiple modalities in alignment to achieve joint reference. To investigate this, we systematically track the emergence of lexical and gestural alignment in a referential communication task with novel objects. Quantitative analyses reveal that people frequently use a combination of lexical and gestural alignment, and that such multimodal alignment tends to emerge earlier compared to unimodal alignment. Qualitative analyses of the interactional contexts in which alignment emerges reveal how people flexibly deploy lexical and gestural alignment (independently, simultaneously or successively) to adjust to communicative pressures.

Abstract

Aging appears to impair the ability to adapt speech and gestures based on knowledge shared with an addressee
(common ground-based recipient design) in narrative settings. Here, we test whether this extends to spatial settings
and is modulated by cognitive abilities. Younger and older adults gave instructions on how to assemble 3D-
models from building blocks on six consecutive trials. We induced mutually shared knowledge by either
showing speaker and addressee the model beforehand, or not. Additionally, shared knowledge accumulated
across the trials. Younger and crucially also older adults provided recipient-designed utterances, indicated by a
significant reduction in the number of words and of gestures when common ground was present. Additionally, we
observed a reduction in semantic content and a shift in cross-modal distribution of information across trials.
Rather than age, individual differences in verbal and visual working memory and semantic fluency predicted the
extent of addressee-based adaptations. Thus, in spatial tasks, individual cognitive abilities modulate the inter-
active language use of both younger and older adul

Abstract

Sign languages use multiple articulators and iconicity in the visual modality which allow linguistic units to be organized not only linearly but also simultaneously. Recent research has shown that users of an established sign language such as LIS (Italian Sign Language) use simultaneous and iconic constructions as a modality-specific resource to achieve communicative efficiency when they are required to encode informationally rich events. However, it remains to be explored whether the use of such simultaneous and iconic constructions recruited for communicative efficiency can be employed even without a linguistic system (i.e., in silent gesture) or whether they are specific to linguistic patterning (i.e., in LIS). In the present study, we conducted the same experiment as in Slonimska et al. with 23 Italian speakers using silent gesture and compared the results of the two studies. The findings showed that while simultaneity was afforded by the visual modality to some extent, its use in silent gesture was nevertheless less frequent and qualitatively different than when used within a linguistic system. Thus, the use of simultaneous and iconic constructions for communicative efficiency constitutes an emergent property of sign languages. The present study highlights the importance of studying modality-specific resources and their use for linguistic expression in order to promote a more thorough understanding of the language faculty and its modality-specific adaptive capabilities.

Abstract

Language development research suggests a universal tendency for children to be under- informative in narrating motion events by omitting components such as Path, Manner or Ground. However, this assumption has not been tested for children acquiring sign language. Due to the affordances of the visual-spatial modality of sign languages for iconic expression, signing children might omit event components less frequently than speaking children. Here we analysed motion event descriptions elicited from deaf children (4–10 years) acquiring Turkish Sign Language (TİD) and their Turkish-speaking peers. While children omitted all types of event components more often than adults, signing children and adults encoded more Path and Manner in TİD than their peers in Turkish. These results provide more evidence for a general universal tendency for children to omit event components as well as a modality bias for sign languages to encode both Manner and Path more frequently than spoken languages.

Abstract

Previous research has shown that spatial language is sensitive to the effects of delayed language exposure. Locative encodings of late-signing deaf adults varied from those of early-signing deaf adults in the preferred types of linguistic forms. In the current study, we investigated whether such differences would be found in spatial language use of deaf children with deaf parents who are either early or late signers of Turkish Sign Language (TİD). We analyzed locative encodings elicited from these two groups of deaf children for the use of different linguistic forms and the types of classifier handshapes. Our findings revealed differences between these two groups of deaf children in their preferred types of linguistic forms, which showed parallels to differences between late versus early deaf adult signers as reported by earlier studies. Deaf children in the current study, however, were similar to each other in the type of classifier handshapes that they used in their classifier constructions. Our findings have implications for expanding current knowledge on to what extent variation in language input (i.e., from early vs. late deaf signers) is reflected in children’s productions as well as the role of linguistic input on language development in general.

Abstract

Every day people see, describe, and remember motion events. However, the relation between multimodal encoding of motion events in speech and gesture, and memory is not yet fully understood. Moreover, whether language typology modulates this relation remains to be tested. This study investigates whether the type of motion event information (path or manner) mentioned in speech and gesture predicts which information is remembered and whether this varies across speakers of typologically different languages. Dutch- and Turkish-speakers watched and described motion events and completed a surprise recognition memory task. For both Dutch- and Turkish-speakers, manner memory was at chance level. Participants who mentioned path in speech during encoding were more accurate at detecting changes to the path in the memory task. The relation between mentioning path in speech and path memory did not vary cross-linguistically. Finally, the co-speech gesture did not predict memory above mentioning path in speech. These findings suggest that how speakers describe a motion event in speech is more important than the typology of the speakers’ native language in predicting motion event memory. The motion event videos are available for download for future research at https://osf.io/p8cas/.

Abstract

Persons with and without autism process sensory information differently. Differences in sensory processing are directly relevant to social functioning and communicative abilities, which are known to be hampered in persons with autism. We collected functional magnetic resonance imaging (fMRI) data from 25 autistic individuals and 25 neurotypical individuals while they performed a silent gesture recognition task. We exploited brain network topology, a holistic quantification of how networks within the brain are organized to provide new insights into how visual communicative signals are processed in autistic and neurotypical individuals. Performing graph theoretical analysis, we calculated two network properties of the action observation network: local efficiency, as a measure of network segregation, and global efficiency, as a measure of network integration. We found that persons with autism and neurotypical persons differ in how the action observation network is organized. Persons with autism utilize a more clustered, local-processing-oriented network configuration (i.e., higher local efficiency), rather than the more integrative network organization seen in neurotypicals (i.e., higher global efficiency). These results shed new light on the complex interplay between social and sensory processing in autism.

Abstract

Speakers’ visual attention to events is guided by linguistic conceptualization of information in spoken language
production and in language-specific ways. Does production of language-specific co-speech gestures further guide
speakers’ visual attention during message preparation? Here, we examine the link between visual attention and
multimodal event descriptions in Turkish. Turkish is a verb-framed language where speakers’ speech and gesture
show language specificity with path of motion mostly expressed within the main verb accompanied by path
gestures. Turkish-speaking adults viewed motion events while their eye movements were recorded during non-
linguistic (viewing-only) and linguistic (viewing-before-describing) tasks. The relative attention allocated to path
over manner was higher in the linguistic task compared to the non-linguistic task. Furthermore, the relative
attention allocated to path over manner within the linguistic task was higher when speakers (a) encoded path in
the main verb versus outside the verb and (b) used additional path gestures accompanying speech versus not.
Results strongly suggest that speakers’ visual attention is guided by language-specific event encoding not only in
speech but also in gesture. This provides evidence consistent with models that propose integration of speech and
gesture at the conceptualization level of language production and suggests that the links between the eye and the
mouth may be extended to the eye and the hand.

Abstract

There is a strong relation between children’s exposure to
spatial terms and their later memory accuracy. In the current
study, we tested whether the production of spatial terms by
children themselves predicts memory accuracy and whether
and how language modality of these encodings modulates
memory accuracy differently. Hearing child speakers of
Turkish and deaf child signers of Turkish Sign Language
described pictures of objects in various spatial relations to each
other and later tested for their memory accuracy of these
pictures in a surprise memory task. We found that having
described the spatial relation between the objects predicted
better memory accuracy. However, the modality of these
descriptions in sign, speech, or speech-plus-gesture did not
reveal differences in memory accuracy. We discuss the
implications of these findings for the relation between spatial
language, memory, and the modality of encoding.

Abstract

Late exposure to the first language, as in the case of deaf children with hearing parents, hinders the production of linguistic expressions, even in adulthood. Less is known about the development of language soon after language exposure and if late exposure hinders all domains of language in children and adults. We compared late signing adults and children (MAge = 8;5) 2 years after exposure to sign language, to their age-matched native signing peers in expressions of two types of locative relations that are acquired in certain cognitive-developmental order: view-independent (IN-ON-UNDER) and view-dependent (LEFT-RIGHT). Late signing children and adults differed from native signers in their use of linguistic devices for view-dependent relations but not for view-independent relations. These effects were also modulated by the morphological complexity. Hindering effects of late language exposure on the development of language in children and adults are not absolute but are modulated by cognitive and linguistic complexity.

Abstract

Visual and auditory channels have different affordances and
this is mirrored in what information is available for linguistic
encoding. The visual channel has high spatial acuity, whereas
the auditory channel has better temporal acuity. These
differences may lead to different conceptualizations of events
and affect multimodal language production. Previous studies of
motion events typically present visual input to elicit speech and
gesture. The present study compared events presented as audio-
only, visual-only, or multimodal (visual+audio) input and
assessed speech and co-speech gesture for path and manner of
motion in Turkish. Speakers with audio-only input mentioned
path more and manner less in verbal descriptions, compared to
speakers who had visual input. There was no difference in the
type or frequency of gestures across conditions, and gestures
were dominated by path-only gestures. This suggests that input
modality influences speakers’ encoding of path and manner of
motion events in speech, but not in co-speech gestures.

Abstract

Bimodal bilinguals are hearing individuals fluent in a sign and a spoken language. Can the two languages influence each other in such individuals despite differences in the visual (sign) and vocal (speech) modalities of expression? We investigated cross-linguistic influences on bimodal bilinguals’ expression of spatial relations. Unlike spoken languages, sign uses iconic linguistic forms that resemble physical features of objects in a spatial relation and thus expresses specific semantic information. Hearing bimodal bilinguals (n = 21) fluent in Dutch and Sign Language of the Netherlands and their hearing nonsigning and deaf signing peers (n = 20 each) described left/right relations between two objects. Bimodal bilinguals expressed more specific information about physical features of objects in speech than nonsigners, showing influence from sign language. They also used fewer iconic signs with specific semantic information than deaf signers, demonstrating influence from speech. Bimodal bilinguals’ speech and signs are shaped by two languages from different modalities.

Abstract

Language in its primary face-to-face context is multimodal (e.g., Holler and Levinson, 2019; Perniss, 2018). Thus, understanding how expressions in the vocal and visual modalities together contribute to our notions of language structure, use, processing, and transmission (i.e., acquisition, evolution, emergence) in different languages and cultures should be a fundamental goal of language sciences. This requires a new framework of language that brings together how arbitrary and non-arbitrary and motivated semiotic resources of language relate to each other. Current commentary evaluates such a proposal by Murgiano et al (2021) from a crosslinguistic perspective taking variation as well as systematicity in multimodal utterances into account.

Abstract

Silent gestures consist of complex multi-articulatory movements but are now primarily studied through categorical coding of the referential gesture content. The relation of categorical linguistic content with continuous kinematics is therefore poorly understood. Here, we reanalyzed the video data from a gestural evolution experiment (Motamedi, Schouwstra, Smith, Culbertson, & Kirby, 2019), which showed increases in the systematicity of gesture content over time. We applied computer vision techniques to quantify the kinematics of the original data. Our kinematic analyses demonstrated that gestures become more efficient and less complex in their kinematics over generations of learners. We further detect the systematicity of gesture form on the level of thegesture kinematic interrelations, which directly scales with the systematicity obtained on semantic coding of the gestures. Thus, from continuous kinematics alone, we can tap into linguistic aspects that were previously only approachable through categorical coding of meaning. Finally, going beyond issues of systematicity, we show how unique gesture kinematic dialects emerged over generations as isolated chains of participants gradually diverged over iterations from other chains. We, thereby, conclude that gestures can come to embody the linguistic system at the level of interrelationships between communicative tokens, which should calibrate our theories about form and linguistic content.

Abstract

When comprehending speech-in-noise (SiN), younger and older adults benefit from seeing the speaker’s mouth, i.e. visible speech. Younger adults additionally benefit from manual iconic co-speech gestures. Here, we investigate to what extent younger and older adults benefit from perceiving both visual articulators while comprehending SiN, and whether this is modulated by working memory and inhibitory control. Twenty-eight younger and 28 older adults performed a word recognition task in three visual contexts: mouth blurred (speech-only), visible speech, or visible speech + iconic gesture. The speech signal was either clear or embedded in multitalker babble. Additionally, there were two visual-only conditions (visible speech, visible speech + gesture). Accuracy levels for both age groups were higher when both visual articulators were present compared to either one or none. However, older adults received a significantly smaller benefit than younger adults, although they performed equally well in speech-only and visual-only word recognition. Individual differences in verbal working memory and inhibitory control partly accounted for age-related performance differences. To conclude, perceiving iconic gestures in addition to visible speech improves younger and older adults’ comprehension of SiN. Yet, the ability to benefit from this additional visual information is modulated by age and verbal working memory. Future research will have to show whether these findings extend beyond the single word level.

Abstract

Meanings communicated with depictions constitute an integral part of how speakers and signers actually use language (Clark, 2016). Recent studies have argued that, in sign languages, depicting strategy like constructed action (CA), in which a signer enacts the referent, is used for referential purposes in narratives. Here, we tested the referential function of CA in a more controlled experimental setting and outside narrative context. Given the iconic properties of CA we hypothesized that this strategy could be used for efficient information transmission. Thus, we asked if use of CA increased with the increase in the information required to be communicated. Twenty-three deaf signers of LIS described unconnected images, which varied in the amount of information represented, to another player in a director–matcher game. Results revealed that participants used CA to communicate core information about the images and also increased the use of CA as images became informatively denser. The findings show that iconic features of CA can be used for referential function in addition to its depictive function outside narrative context and to achieve communicative efficiency.

Abstract

In everyday conversation, we are often challenged with communicating in non-ideal settings, such as in noise. Increased speech intensity and larger mouth movements are used to overcome noise in constrained settings (the Lombard effect). How we adapt to noise in face-to-face interaction, the natural environment of human language use, where manual gestures are ubiquitous, is currently unknown. We asked Dutch adults to wear headphones with varying levels of multi-talker babble while attempting to communicate action verbs to one another. Using quantitative motion capture and acoustic analyses, we found that (1) noise is associated with increased speech intensity and enhanced gesture kinematics and mouth movements, and (2) acoustic modulation only occurs when gestures are not present, while kinematic modulation occurs regardless of co-occurring speech. Thus, in face-to-face encounters the Lombard effect is not constrained to speech but is a multimodal phenomenon where the visual channel carries most of the communicative burden.

Abstract

In human communication, social intentions and meaning are often revealed in the way we move. In this study, we investigate the flexibility of human communication in terms of kinematic modulation in a clinical population, namely, autistic individuals. The aim of this study was twofold: to assess (a) whether communicatively relevant kinematic features of gestures differ between autistic and neurotypical individuals, and (b) if autistic individuals use communicative kinematic modulation to support gesture recognition. We tested autistic and neurotypical individuals on a silent gesture production task and a gesture comprehension task. We measured movement during the gesture production task using a Kinect motion tracking device in order to determine if autistic individuals differed from neurotypical individuals in their gesture kinematics. For the gesture comprehension task, we assessed whether autistic individuals used communicatively relevant kinematic cues to support recognition. This was done by using stick-light figures as stimuli and testing for a correlation between the kinematics of these videos and recognition performance. We found that (a) silent gestures produced by autistic and neurotypical individuals differ in communicatively relevant kinematic features, such as the number of meaningful holds between movements, and (b) while autistic individuals are overall unimpaired at recognizing gestures, they processed repetition and complexity, measured as the amount of submovements perceived, differently than neurotypicals do. These findings highlight how subtle aspects of neurotypical behavior can be experienced differently by autistic individuals. They further demonstrate the relationship between movement kinematics and social interaction in high-functioning autistic individuals.

Abstract

This paper investigates whether there are changes in gesture rate when speakers of two languages with different gesture rates (Turkish-high gesture; Dutch-low gesture) come into daily contact. We analyzed gestures produced by second-generation heritage speakers of Turkish in the Netherlands in each language, comparing them to monolingual baselines. We did not find differences between bilingual and monolingual speakers, possibly because bilinguals were proficient in both languages and used them frequently – in line with a usage-based approach to language. However, bilinguals produced more deictic gestures than monolinguals in both Turkish and Dutch, which we interpret as a bilingual strategy. Deictic gestures may help organize discourse by placing entities in gesture space and help reduce the cognitive load associated with being bilingual, e.g., inhibition cost. Therefore, gesture rate does not necessarily change in contact situations but might be modulated by frequency of language use, proficiency, and cognitive factors related to being bilingual.

Abstract

Aim:

This paper examines whether second-generation Turkish heritage speakers in the Netherlands follow language-specific patterns of reference tracking in Turkish and Dutch, focusing on discourse status and pragmatic contexts as factors that may modulate the choice of referring expressions (REs), that is, the noun phrase (NP), overt pronoun and null pronoun.
Methodology:

Two short silent videos were used to elicit narratives from 20 heritage speakers of Turkish, both in Turkish and in Dutch. Monolingual baseline data were collected from 20 monolingually raised speakers of Turkish in Turkey and 20 monolingually raised speakers of Dutch in the Netherlands. We also collected language background data from bilinguals with an extensive survey.
Data and analysis:

Using generalised logistic mixed-effect regression, we analysed the influence of discourse status and pragmatic context on the choice of subject REs in Turkish and Dutch, comparing bilingual data to the monolingual baseline in each language.
Findings:

Heritage speakers used overt versus null pronouns in Turkish and stressed versus reduced pronouns in Dutch in pragmatically appropriate contexts. There was, however, a slight increase in the proportions of overt pronouns as opposed to NPs in Turkish and as opposed to null pronouns in Dutch. We suggest an explanation based on the degree of entrenchment of differential RE types in relation to discourse status as the possible source of the increase.
Originality:

This paper provides data from an understudied language pair in the domain of reference tracking in language contact situations. Unlike several studies of pronouns in language contact, we do not find differences across monolingual and bilingual speakers with regard to pragmatic constraints on overt pronouns in the minority pro-drop language.
Significance:

Our findings highlight the importance of taking language proficiency and use into account while studying bilingualism and combining formal approaches to language use with usage-based approaches for a more complete understanding of bilingual language production.

Abstract

Native listeners benefit from both visible speech and iconic gestures to enhance degraded speech comprehension (Drijvers & Ozyürek, 2017). We tested how highly proficient non-native listeners benefit from these visual articulators compared to native listeners. We presented videos of an actress uttering a verb in clear, moderately, or severely degraded speech, while her lips were blurred, visible, or visible and accompanied by a gesture. Our results revealed that unlike native listeners, non-native listeners were less likely to benefit from the combined enhancement of visible speech and gestures, especially since the benefit from visible speech was minimal when the signal quality was not sufficient.

Abstract

Face-to-face communication is multimodal at its core: it consists of a combination of vocal and visual signalling. However, current evidence suggests that, in the absence of an established communication system, visual signalling, especially in the form of visible gesture, is a more powerful form of communication than vocalisation, and therefore likely to have played a primary role in the emergence of human language. This argument is based on experimental evidence of how vocal and visual modalities (i.e., gesture) are employed to communicate about familiar concepts when participants cannot use their existing languages. To investigate this further, we introduce an experiment where pairs of participants performed a referential communication task in which they described unfamiliar stimuli in order to reduce reliance on conventional signals. Visual and auditory stimuli were described in three conditions: using visible gestures only, using non-linguistic vocalisations only and given the option to use both (multimodal communication). The results suggest that even in the absence of conventional signals, gesture is a more powerful mode of communication compared to vocalisation, but that there are also advantages to multimodality compared to using gesture alone. Participants with an option to produce multimodal signals had comparable accuracy to those using only gesture, but gained an efficiency advantage. The analysis of the interactions between participants showed that interactants developed novel communication systems for unfamiliar stimuli by deploying different modalities flexibly to suit their needs and by taking advantage of multimodality when required.

Abstract

To talk about space, spoken languages rely on arbitrary and categorical forms (e.g., left, right). In sign languages, however, the visual–spatial modality allows for iconic encodings (motivated form-meaning mappings) of space in which form and location of the hands bear resemblance to the objects and spatial relations depicted. We assessed whether the iconic encodings in sign languages guide visual attention to spatial relations differently than spatial encodings in spoken languages during message preparation at the sentence level. Using a visual world production eye-tracking paradigm, we compared 20 deaf native signers of Sign-Language-of-the-Netherlands and 20 Dutch speakers’ visual attention to describe left versus right configurations of objects (e.g., “pen is to the left/right of cup”). Participants viewed 4-picture displays in which each picture contained the same 2 objects but in different spatial relations (lateral [left/right], sagittal [front/behind], topological [in/on]) to each other. They described the target picture (left/right) highlighted by an arrow. During message preparation, signers, but not speakers, experienced increasing eye-gaze competition from other spatial configurations. This effect was absent during picture viewing prior to message preparation of relational encoding. Moreover, signers’ visual attention to lateral and/or sagittal relations was predicted by the type of iconicity (i.e., object and space resemblance vs. space resemblance only) in their spatial descriptions. Findings are discussed in relation to how “thinking for speaking” differs from “thinking for signing” and how iconicity can mediate the link between language and human experience and guides signers’ but not speakers’ attention to visual aspects of the world.

Abstract

When learning a second spoken language, cognates, words overlapping in form and meaning with one’s native language, help breaking into the language one wishes to acquire. But what happens when the to-be-acquired second language is a sign language? We tested whether hearing nonsigners rely on their gestural repertoire at first exposure to a sign language. Participants saw iconic signs with high and low overlap with the form of iconic gestures while electrophysiological brain activity was recorded. Upon first exposure, signs with low overlap with gestures elicited enhanced positive amplitude in the P3a component compared to signs with high overlap. This effect disappeared after a training session. We conclude that nonsigners generate expectations about the form of iconic signs never seen before based on their implicit knowledge of gestures, even without having to produce them. Learners thus draw from any available semiotic resources when acquiring a second language, and not only from their linguistic experience

Abstract

An unprecedented number of empirical studies have shown that iconic gestures—those that mimic the sensorimotor attributes of a referent—contribute significantly to language acquisition, perception, and processing. However, there has been a lack of normed studies describing generalizable principles in gesture production and in comprehension of the mappings of different types of iconic strategies (i.e., modes of representation; Müller, 2013). In Study 1 we elicited silent gestures in order to explore the implementation of different types of iconic representation (i.e., acting, representing, drawing, and personification) to express concepts across five semantic domains. In Study 2 we investigated the degree of meaning transparency (i.e., iconicity ratings) of the gestures elicited in Study 1. We found systematicity in the gestural forms of 109 concepts across all participants, with different types of iconicity aligning with specific semantic domains: Acting was favored for actions and manipulable objects, drawing for nonmanipulable objects, and personification for animate entities. Interpretation of gesture–meaning transparency was modulated by the interaction between mode of representation and semantic domain, with some couplings being more transparent than others: Acting yielded higher ratings for actions, representing for object-related concepts, personification for animate entities, and drawing for nonmanipulable entities. This study provides mapping principles that may extend to all forms of manual communication (gesture and sign). This database includes a list of the most systematic silent gestures in the group of participants, a notation of the form of each gesture based on four features (hand configuration, orientation, placement, and movement), each gesture’s mode of representation, iconicity ratings, and professionally filmed videos that can be used for experimental and clinical endeavors.

Abstract

In this study we explore whether different types of iconic gestures
(i.e., acting, drawing, representing) and their combinations are used
systematically to distinguish between different semantic categories in
production and comprehension. In Study 1, we elicited silent gestures
from Mexican and Dutch participants to represent concepts from three
semantic categories: actions, manipulable objects, and non-manipulable
objects. Both groups favoured the acting strategy to represent actions and
manipulable objects; while non-manipulable objects were represented
through the drawing strategy. Actions elicited primarily single gestures
whereas objects elicited combinations of different types of iconic gestures
as well as pointing. In Study 2, a different group of participants were
shown gestures from Study 1 and were asked to guess their meaning.
Single-gesture depictions for actions were more accurately guessed than
for objects. Objects represented through two-gesture combinations (e.g.,
acting + drawing) were more accurately guessed than objects represented
with a single gesture. We suggest iconicity is exploited to make direct
links with a referent, but when it lends itself to ambiguity, individuals
resort to combinatorial structures to clarify the intended referent.
Iconicity and the need to communicate a clear signal shape the structure
of silent gestures and this in turn supports comprehension.

Abstract

When people are engaged in social interaction, they can repeat aspects of each other’s communicative behavior, such as words or gestures. This kind of behavioral alignment has been studied across a wide range of disciplines and has been accounted for by diverging theories. In this paper, we review various operationalizations of lexical and gestural alignment. We reveal that scholars have fundamentally different takes on when and how behavior is considered to be aligned, which makes it difficult to compare findings and draw uniform conclusions. Furthermore, we show that scholars tend to focus on one particular dimension of alignment (traditionally, whether two instances of behavior overlap in form), while other dimensions remain understudied. This hampers theory testing and building, which requires a well‐defined account of the factors that are central to or might enhance alignment. To capture the complex nature of alignment, we identify five key dimensions to formalize the relationship between any pair of behavior: time, sequence, meaning, form, and modality. We show how assumptions regarding the underlying mechanism of alignment (placed along the continuum of priming vs. grounding) pattern together with operationalizations in terms of the five dimensions. This integrative framework can help researchers in the field of alignment and related phenomena (including behavior matching, mimicry, entrainment, and accommodation) to formulate their hypotheses and operationalizations in a more transparent and systematic manner. The framework also enables us to discover unexplored research avenues and derive new hypotheses regarding alignment.

Abstract

Children perceive iconic gestures, along with speech they hear. Previous studies have shown
that children integrate information from both modalities. Yet it is not known whether children
can integrate both types of information simultaneously as soon as they are available as adults
do or processes them separately initially and integrate them later. Using electrophysiological
measures, we examined the online neurocognitive processing of gesture-speech integration in
6- to 7-year-old children. We focused on the N400 event-related potentials component which
is modulated by semantic integration load. Children watched video clips of matching or
mismatching gesture-speech combinations, which varied the semantic integration load. The
ERPs showed that the amplitude of the N400 was larger in the mismatching condition than in
the matching condition. This finding provides the first neural evidence that by the ages of 6
or 7, children integrate multimodal semantic information in an online fashion comparable to
that of adults.

Abstract

A fundamental assumption about language is that, regardless of language modality, it faces the linearization problem, i.e., an event that occurs simultaneously in the world has to be split in language to be organized on a temporal scale. However, the visual modality of signed languages allows its users not only to express meaning in a linear manner but also to use iconicity and multiple articulators together to encode information simultaneously. Accordingly, in cases when it is necessary to encode informatively rich events, signers can take advantage of simultaneous encoding in order to represent information about different referents and their actions simultaneously. This in turn would lead to more iconic and direct representation. Up to now, there has been no experimental study focusing on simultaneous encoding of information in signed languages and its possible advantage for efficient communication. In the present study, we assessed how many information units can be encoded simultaneously in Italian Sign Language (LIS) and whether the amount of simultaneously encoded information varies based on the amount of information that is required to be expressed. Twenty-three deaf adults participated in a director-matcher game in which they described 30 images of events that varied in amount of information they contained. Results revealed that as the information that had to be encoded increased, signers also increased use of multiple articulators to encode different information (i.e., kinematic simultaneity) and density of simultaneously encoded information in their production. Present findings show how the fundamental properties of signed languages, i.e., iconicity and simultaneity, are used for the purpose of efficient information encoding in Italian Sign Language (LIS).

Abstract

Linguistic expressions of locative spatial relations in sign languages are mostly visually- motivated representations of space involving mapping of entities and spatial relations between them onto the hands and the signing space. These are also morphologically complex forms. It is debated whether modality-specific aspects of spatial expressions modulate spatial language development differently in signing compared to speaking children. In a picture description task, we compared the use of locative expressions for containment, support and occlusion relations by deaf children acquiring Turkish Sign Language and hearing children acquiring Turkish (3;5-9;11 years). Unlike previous reports suggesting a boosting effect of iconicity, and / or a hindering effect of morphological complexity of the locative forms in sign languages, our results show similar developmental patterns for signing and speaking children's acquisition of these forms. Our results suggest the primacy of cognitive development guiding the acquisition of locative expressions by speaking and signing children.

Abstract

Humans are unique in their ability to communicate information through representational gestures which visually simulate an action (eg. moving hands as if opening a jar). Previous research indicates that the intention to communicate modulates the kinematics (e.g., velocity, size) of such gestures. If and how this modulation influences addressees’ comprehension of gestures have not been investigated. Here we ask whether communicative kinematic modulation enhances semantic comprehension (i.e., identification) of gestures. We additionally investigate whether any comprehension advantage is due to enhanced early identification or late identification. Participants (n = 20) watched videos of representational gestures produced in a more- (n = 60) or less-communicative (n = 60) context and performed a forced-choice recognition task. We tested the isolated role of kinematics by removing visibility of actor’s faces in Experiment I, and by reducing the stimuli to stick-light figures in Experiment II. Three video lengths were used to disentangle early identification from late identification. Accuracy and response time quantified main effects. Kinematic modulation was tested for correlations with task performance. We found higher gesture identification performance in more- compared to less-communicative gestures. However, early identification was only enhanced within a full visual context, while late identification occurred even when viewing isolated kinematics. Additionally, temporally segmented acts with more post-stroke holds were associated with higher accuracy. Our results demonstrate that communicative signaling, interacting with other visual cues, generally supports gesture identification, while kinematic modulation specifically enhances late identification in the absence of other cues. Results provide insights into mutual understanding processes as well as creating artificial communicative agents.

Abstract

Social interaction requires us to recognize subtle cues in behavior, such as kinematic differences in actions and gestures produced with different social intentions. Neuroscientific studies indicate that the putative mirror neuron system (pMNS) in the premotor cortex and mentalizing system (MS) in the medial prefrontal cortex support inferences about contextually unusual actions. However, little is known regarding the brain dynamics of these systems when viewing communicatively exaggerated kinematics. In an event-related functional magnetic resonance imaging experiment, 28 participants viewed stick-light videos of pantomime gestures, recorded in a previous study, which contained varying degrees of communicative exaggeration. Participants made either social or nonsocial classifications of the videos. Using participant responses and pantomime kinematics, we modeled the probability of each video being classified as communicative. Interregion connectivity and activity were modulated by kinematic exaggeration, depending on the task. In the Social Task, communicativeness of the gesture increased activation of several pMNS and MS regions and modulated top-down coupling from the MS to the pMNS, but engagement of the pMNS and MS was not found in the nonsocial task. Our results suggest that expectation violations can be a key cue for inferring communicative intention, extending previous findings from wholly unexpected actions to more subtle social signaling.

Abstract

Referent accessibility influences expressions in speech and gestures in similar ways. Speakers mostly use richer forms as noun phrases (NPs) in speech and gesture more when referents have low accessibility, whereas they use reduced forms such as pronouns more often and gesture less when referents have high accessibility. We investigated the relationships between speech and gesture during reference tracking in a pro-drop language—Turkish. Overt pronouns were not strongly associated with accessibility but with pragmatic context (i.e., marking similarity, contrast). Nevertheless, speakers gestured more when referents were re-introduced versus maintained and when referents were expressed with NPs versus pronouns. Pragmatic context did not influence gestures. Further, pronouns in low-accessibility contexts were accompanied with gestures—possibly for reference disambiguation—more often than previously found for non-pro-drop languages in such contexts. These findings enhance our understanding of the relationships between speech and gesture at the discourse level.

Abstract

Visual information conveyed by iconic hand gestures and visible speech can enhance speech comprehension under adverse listening conditions for both native and non‐native listeners. However, how a listener allocates visual attention to these articulators during speech comprehension is unknown. We used eye‐tracking to investigate whether and how native and highly proficient non‐native listeners of Dutch allocated overt eye gaze to visible speech and gestures during clear and degraded speech comprehension. Participants watched video clips of an actress uttering a clear or degraded (6‐band noise‐vocoded) action verb while performing a gesture or not, and were asked to indicate the word they heard in a cued‐recall task. Gestural enhancement was the largest (i.e., a relative reduction in reaction time cost) when speech was degraded for all listeners, but it was stronger for native listeners. Both native and non‐native listeners mostly gazed at the face during comprehension, but non‐native listeners gazed more often at gestures than native listeners. However, only native but not non‐native listeners' gaze allocation to gestures predicted gestural benefit during degraded speech comprehension. We conclude that non‐native listeners might gaze at gesture more as it might be more challenging for non‐native listeners to resolve the degraded auditory cues and couple those cues to phonological information that is conveyed by visible speech. This diminished phonological knowledge might hinder the use of semantic information that is conveyed by gestures for non‐native compared to native listeners. Our results demonstrate that the degree of language experience impacts overt visual attention to visual articulators, resulting in different visual benefits for native versus non‐native listeners.

Abstract

Listeners are often challenged by adverse listening conditions during language comprehension induced by external factors, such as noise, but also internal factors, such as being a non-native listener. Visible cues, such as semantic information conveyed by iconic gestures, can enhance language comprehension in such situations. Using magnetoencephalography (MEG) we investigated whether spatiotemporal oscillatory dynamics can predict a listener's benefit of iconic gestures during language comprehension in both internally (non-native versus native listeners) and externally (clear/degraded speech) induced adverse listening conditions. Proficient non-native speakers of Dutch were presented with videos in which an actress uttered a degraded or clear verb, accompanied by a gesture or not, and completed a cued-recall task after every video. The behavioral and oscillatory results obtained from non-native listeners were compared to an MEG study where we presented the same stimuli to native listeners (Drijvers et al., 2018a). Non-native listeners demonstrated a similar gestural enhancement effect as native listeners, but overall scored significantly slower on the cued-recall task. In both native and non-native listeners, an alpha/beta power suppression revealed engagement of the extended language network, motor and visual regions during gestural enhancement of degraded speech comprehension, suggesting similar core processes that support unification and lexical access processes. An individual's alpha/beta power modulation predicted the gestural benefit a listener experienced during degraded speech comprehension. Importantly, however, non-native listeners showed less engagement of the mouth area of the primary somatosensory cortex, left insula (beta), LIFG and ATL (alpha) than native listeners, which suggests that non-native listeners might be hindered in processing the degraded phonological cues and coupling them to the semantic information conveyed by the gesture. Native and non-native listeners thus demonstrated similar yet distinct spatiotemporal oscillatory dynamics when recruiting visual cues to disambiguate degraded speech.

Abstract

Studies have claimed that blind people’s spatial representations are different from sighted people, and blind people display superior auditory processing. Due to the nature of auditory and haptic information, it has been proposed that blind people have spatial representations that are more sequential than sighted people. Even the temporary loss of sight—such as through blindfolding—can affect spatial representations, but not much research has been done on this topic. We compared blindfolded and sighted people’s linguistic spatial expressions and non-linguistic localization accuracy to test how blindfolding affects the representation of path in auditory motion events. We found that blindfolded people were as good as sighted people when localizing simple sounds, but they outperformed sighted people when localizing auditory motion events. Blindfolded people’s path related speech also included more sequential, and less holistic elements. Our results indicate that even temporary loss of sight influences spatial representations of auditory motion events

Abstract

The sign languages of deaf communities and the gestures produced by hearing people are communicative systems that exploit the manual-visual modality as means of expression. Despite their striking differences they share the property of iconicity, understood as the direct relationship between a symbol and its referent. Here we investigate whether non-signing hearing adults exploit their implicit knowledge of gestures to bootstrap accurate understanding of the meaning of iconic signs they have never seen before. In Study 1 we show that for some concepts gestures exhibit systematic forms across participants, and share different degrees of form overlap with the signs for the same concepts (full, partial, and no overlap). In Study 2 we found that signs with stronger resemblance with signs are more accurately guessed and are assigned higher iconicity ratings by non-signers than signs with low overlap. In addition, when more people produced a systematic gesture resembling a sign, they assigned higher iconicity ratings to that sign. Furthermore, participants had a bias to assume that signs represent actions and not objects. The similarities between some signs and gestures could be explained by deaf signers and hearing gesturers sharing a conceptual substrate that is rooted in our embodied experiences with the world. The finding that gestural knowledge can ease the interpretation of the meaning of novel signs and predicts iconicity ratings is in line with embodied accounts of cognition and the influence of prior knowledge to acquire new schemas. Through these mechanisms we propose that iconic gestures that overlap in form with signs may serve as some type of ‘manual cognates’ that help non-signing adults to break into a new language at first exposure.

Abstract

Speakers can adapt their speech and co-speech gestures based on knowledge shared with an addressee (common ground-based recipient design). Here, we investigate whether these adaptations are modulated by the speaker’s age and cognitive abilities. Younger and older participants narrated six short comic stories to a same-aged addressee. Half of each story was known to both participants, the other half only to the speaker. The two age groups did not differ in terms of the number of words and narrative events mentioned per narration, or in terms of gesture frequency, gesture rate, or percentage of events expressed multimodally. However, only the younger participants reduced the amount of verbal and gestural information when narrating mutually known as opposed to novel story content. Age-related differences in cognitive abilities did not predict these differences in common ground-based recipient design. The older participants’ communicative behaviour may therefore also reflect differences in social or pragmatic goals.

Abstract

In everyday life, people see, describe and remember motion events. We tested whether the type of motion event information (path or manner) encoded in speech and gesture predicts which information is remembered and if this varies across speakers of typologically different languages. We focus on intransitive motion events (e.g., a woman running to a tree) that are described differently in speech and co-speech gesture across languages, based on how these languages typologically encode manner and path information (Kita & Özyürek, 2003; Talmy, 1985). Speakers of Dutch (n = 19) and Turkish (n = 22) watched and described motion events. With a surprise (i.e. unexpected) recognition memory task, memory for manner and path components of these events was measured. Neither Dutch nor Turkish speakers’ memory for manner went above chance levels. However, we found a positive relation between path speech and path change detection: participants who described the path during encoding were more accurate at detecting changes to the path of an event during the memory task. In addition, the relation between path speech and path memory changed with native language: for Dutch speakers encoding path in speech was related to improved path memory, but for Turkish speakers no such relation existed. For both languages, co-speech gesture did not predict memory speakers. We discuss the implications of these findings for our understanding of the relations between speech, gesture, type of encoding in language and memory.

Abstract

Action, gesture, and sign represent unique aspects of human communication that use form and movement to convey meaning. Researchers typically use manual coding of video data to characterize naturalistic, meaningful movements at various levels of description, but the availability of markerless motion-tracking technology allows for quantification of the kinematic features of gestures or any meaningful human movement. We present a novel protocol for extracting a set of kinematic features from movements recorded with Microsoft Kinect. Our protocol captures spatial and temporal features, such as height, velocity, submovements/strokes, and holds. This approach is based on studies of communicative actions and gestures and attempts to capture features that are consistently implicated as important kinematic aspects of communication. We provide open-source code for the protocol, a description of how the features are calculated, a validation of these features as quantified by our protocol versus manual coders, and a discussion of how the protocol can be applied. The protocol effectively quantifies kinematic features that are important in the production (e.g., characterizing different contexts) as well as the comprehension (e.g., used by addressees to understand intent and semantics) of manual acts. The protocol can also be integrated with qualitative analysis, allowing fast and objective demarcation of movement units, providing accurate coding even of complex movements. This can be useful to clinicians, as well as to researchers studying multimodal communication or human–robot interactions. By making this protocol available, we hope to provide a tool that can be applied to understanding meaningful movement characteristics in human communication.

Abstract

Previous work revealed that visual semantic information conveyed by gestures can enhance degraded speech comprehension, but the mechanisms underlying these integration processes under adverse listening conditions remain poorly understood. We used MEG to investigate how oscillatory dynamics support speech–gesture integration when integration load is manipulated by auditory (e.g., speech degradation) and visual semantic (e.g., gesture congruency) factors. Participants were presented with videos of an actress uttering an action verb in clear or degraded speech, accompanied by a matching (mixing gesture + “mixing”) or mismatching (drinking gesture + “walking”) gesture. In clear speech, alpha/beta power was more suppressed in the left inferior frontal gyrus and motor and visual cortices when integration load increased in response to mismatching versus matching gestures. In degraded speech, beta power was less suppressed over posterior STS and medial temporal lobe for mismatching compared with matching gestures, showing that integration load was lowest when speech was degraded and mismatching gestures could not be integrated and disambiguate the degraded signal. Our results thus provide novel insights on how low-frequency oscillatory modulations in different parts of the cortex support the semantic audiovisual integration of gestures in clear and degraded speech: When speech is clear, the left inferior frontal gyrus and motor and visual cortices engage because higher-level semantic information increases semantic integration load. When speech is degraded, posterior STS/middle temporal gyrus and medial temporal lobe are less engaged because integration load is lowest when visual semantic information does not aid lexical retrieval and speech and gestures cannot be integrated.

Abstract

During face-to-face communication, listeners integrate speech with gestures. The semantic information conveyed by iconic gestures (e.g., a drinking gesture) can aid speech comprehension in adverse listening conditions. In this magnetoencephalography (MEG) study, we investigated the spatiotemporal neural oscillatory activity associated with gestural enhancement of degraded speech comprehension. Participants watched videos of an actress uttering clear or degraded speech, accompanied by a gesture or not and completed a cued-recall task after watching every video. When gestures semantically disambiguated degraded speech comprehension, an alpha and beta power suppression and a gamma power increase revealed engagement and active processing in the hand-area of the motor cortex, the extended language network (LIFG/pSTS/STG/MTG), medial temporal lobe, and occipital regions. These observed low- and high-frequency oscillatory modulations in these areas support general unification, integration and lexical access processes during online language comprehension, and simulation of and increased visual attention to manual gestures over time. All individual oscillatory power modulations associated with gestural enhancement of degraded speech comprehension predicted a listener's correct disambiguation of the degraded verb after watching the videos. Our results thus go beyond the previously proposed role of oscillatory dynamics in unimodal degraded speech comprehension and provide first evidence for the role of low- and high-frequency oscillations in predicting the integration of auditory and visual information at a semantic level.

Abstract

Native listeners neurally integrate iconic gestures with speech, which can enhance degraded speech comprehension. However, it is unknown how non-native listeners neurally integrate speech and gestures, as they might process visual semantic context differently than natives. We recorded EEG while native and highly-proficient non-native listeners watched videos of an actress uttering an action verb in clear or degraded speech, accompanied by a matching ('to drive'+driving gesture) or mismatching gesture ('to drink'+mixing gesture). Degraded speech elicited an enhanced N400 amplitude compared to clear speech in both groups, revealing an increase in neural resources needed to resolve the spoken input. A larger N400 effect was found in clear speech for non-natives compared to natives, but in degraded speech only for natives. Non-native listeners might thus process gesture more strongly than natives when speech is clear, but need more auditory cues to facilitate access to gestural semantic information when speech is degraded.

Abstract

Our ability to use language is multimodal and requires tight coordination between what is expressed in speech and in gesture, such as pointing or iconic gestures that convey semantic, syntactic and pragmatic information related to speakers’ messages. Interestingly, what is expressed in gesture and how it is coordinated with speech differs in speakers of different languages. This paper discusses recent findings on the development of children’s multimodal expressions taking cross-linguistic variation into account. Although some aspects of speech-gesture development show language-specificity from an early age, it might still take children until nine years of age to exhibit fully adult patterns of cross-linguistic variation. These findings reveal insights about how children coordinate different levels of representations given that their development is constrained by patterns that are specific to their languages.

Abstract

Use of language in face-to-face context is multimodal. Production and perception of speech take place in the context of visual articulators such as lips, face, or hand gestures which convey relevant information to what is expressed in speech at different levels of language. While lips convey information at the phonological level, gestures contribute to semantic, pragmatic, and syntactic information, as well as to discourse cohesion. This chapter overviews recent findings showing that speech and gesture (e.g. a drinking gesture as someone says, “Would you like a drink?”) interact during production and comprehension of language at the behavioral, cognitive, and neural levels. Implications of these findings for current psycholinguistic theories and how they can be expanded to consider the multimodal context of language processing are discussed.

Abstract

Actions may be used to directly act on the world around us, or as a means of communication. Effective communication requires the addressee to recognize the act as being communicative. Humans are sensitive to ostensive communicative cues, such as direct eye gaze (Csibra & Gergely, 2009). However, there may be additional cues present in the action or gesture itself. Here we investigate features that characterize the initiation of a communicative interaction in both production and comprehension.

We asked 40 participants to perform 31 pairs of object-directed actions and representational gestures in more- or less- communicative contexts. Data were collected using motion capture technology for kinematics and video recording for eye-gaze. With these data, we focused on two issues. First, if and how actions and gestures are systematically modulated when performed in a communicative context. Second, if observers exploit such kinematic information to classify an act as communicative.

Our study showed that during production the communicative context modulates space–time dimensions of kinematics and elicits an increase in addressee-directed eye-gaze. Naïve participants detected communicative intent in actions and gestures preferentially using eye-gaze information, only utilizing kinematic information when eye-gaze was unavailable.

Our study highlights the general communicative modulation of action and gesture kinematics during production but also shows that addressees only exploit this modulation to recognize communicative intention in the absence of eye-gaze. We discuss these findings in terms of distinctive but potentially overlapping functions of addressee directed eye-gaze and kinematic modulations within the wider context of human communication and learning.

Abstract

The use of subject pronouns by bilingual speakers using both a pro-drop and a non-pro-drop language (e.g. Spanish heritage speakers in the USA) is a well-studied topic in research on cross-linguistic influence in language contact situations. Previous studies looking at bilinguals with different proficiency levels have yielded conflicting results on whether there is transfer from the non-pro-drop patterns to the pro-drop language. Additionally, previous research has focused on speech patterns only. In this paper, we study the two modalities of language, speech and gesture, and ask whether and how they reveal cross-linguistic influence on the use of subject pronouns in discourse. We focus on elicited narratives from heritage speakers of Turkish in the Netherlands, in both Turkish (pro-drop) and Dutch (non-pro-drop), as well as from monolingual control groups. The use of pronouns was not very common in monolingual Turkish narratives and was constrained by the pragmatic contexts, unlike in Dutch. Furthermore, Turkish pronouns were more likely to be accompanied by localized gestures than Dutch pronouns, presumably because pronouns in Turkish are pragmatically marked forms. We did not find any cross-linguistic influence in bilingual speech or gesture patterns, in line with studies (speech only) of highly proficient bilinguals. We therefore suggest that speech and gesture parallel each other not only in monolingual but also in bilingual production. Highly proficient heritage speakers who have been exposed to diverse linguistic and gestural patterns of each language from early on maintain monolingual patterns of pragmatic constraints on the use of pronouns multimodally.

Abstract

Purpose This study investigated whether and to what extent iconic co-speech gestures contribute to information from visible speech to enhance degraded speech comprehension at different levels of noise-vocoding. Previous studies of the contributions of these 2 visual articulators to speech comprehension have only been performed separately.

Method Twenty participants watched videos of an actress uttering an action verb and completed a free-recall task. The videos were presented in 3 speech conditions (2-band noise-vocoding, 6-band noise-vocoding, clear), 3 multimodal conditions (speech + lips blurred, speech + visible speech, speech + visible speech + gesture), and 2 visual-only conditions (visible speech, visible speech + gesture).

Results Accuracy levels were higher when both visual articulators were present compared with 1 or none. The enhancement effects of (a) visible speech, (b) gestural information on top of visible speech, and (c) both visible speech and iconic gestures were larger in 6-band than 2-band noise-vocoding or visual-only conditions. Gestural enhancement in 2-band noise-vocoding did not differ from gestural enhancement in visual-only conditions.

Abstract

Deaf children born to hearing parents are exposed to language input quite late, which has long-lasting effects on language production. Previous studies with deaf individuals mostly focused on linguistic expressions of motion events, which have several event components. We do not know if similar effects emerge in simple events such as descriptions of spatial configurations of objects. Moreover, previous data mainly come from late adult signers. There is not much known about language development of late signing children soon after learning sign language. We compared simple event descriptions of late signers of Turkish Sign Language (adults, children) to age-matched native signers. Our results indicate that while late signers in both age groups are native-like in frequency of expressing a relational encoding, they lag behind native signers in using morphologically complex linguistic forms compared to other simple forms. Late signing children perform similar to adults and thus showed no development over time.

Abstract

Language development is driven by multiple factors involving both the individual child and the environments that surround the child. The chapters in this volume highlight several such factors as potential contributors to developmental change, including factors that examine the role of immediate social environment (i.e., parent SES, parent and sibling input, peer interaction) and factors that focus on the child’s own cognitive and social development, such as the acquisition of theory of mind, event knowledge, and memory. The discussion of the different factors is presented largely from a crosslinguistic framework, using a multimodal perspective (speech, gesture, sign). The book celebrates the scholarly contributions of Prof. Ayhan Aksu-Koç – a pioneer in the study of crosslinguistic variation in language acquisition, particularly in the domain of evidentiality and theory of mind. This book will serve as an important resource for researchers in the field of developmental psychology, cognitive science, and linguistics across the globe

Abstract

Sign languages stand out in that there is high prevalence of
conventionalised linguistic forms that map directly to their
referent (i.e., iconic). Hearing adults show low performance
when asked to guess the meaning of iconic signs suggesting
that their iconic features are largely inaccessible to them.
However, it has not been investigated whether speakers’
gestures, which also share the property of iconicity, may
assist non-signers in guessing the meaning of signs. Results
from a pantomime generation task (Study 1) show that
speakers’ gestures exhibit a high degree of systematicity, and
share different degrees of form overlap with signs (full,
partial, and no overlap). Study 2 shows that signs with full
and partial overlap are more accurately guessed and are
assigned higher iconicity ratings than signs with no overlap.
Deaf and hearing adults converge in their iconic depictions
for some concepts due to the shared conceptual knowledge
and manual-visual modality.

Abstract

Recent research on signed as well as spoken language shows that the iconic features of the target language might play a role in language development. Here, we ask further whether different types of iconic depictions modulate children’s preferences for certain types of sign-referent links during vocabulary development in sign language. Results from a picture description task indicate that lexical signs with 2 possible variants are used in different proportions by deaf signers from different age groups. While preschool and school-age children favored variants representing actions associated with their referent (e.g., a writing hand for the sign PEN), adults preferred variants representing the perceptual features of those objects (e.g., upward index finger representing a thin, elongated object for the sign PEN). Deaf parents interacting with their children, however, used action- and perceptual-based variants in equal proportion and favored action variants more than adults signing to other adults. We propose that when children are confronted with 2 variants for the same concept, they initially prefer action-based variants because they give them the opportunity to link a linguistic label to familiar schemas linked to their action/motor experiences. Our results echo findings showing a bias for action-based depictions in the development of iconic co-speech gestures suggesting a modality bias for such representations during development.

Abstract

Most research focuses function of gesture independent of its link to the speech it accompanies and the coexpressive functions it has together with speech. This chapter instead approaches gesture in relation to its communicative function in relation to speech, and demonstrates how it is shaped by the linguistic encoding of a speaker’s message. Drawing on crosslinguistic research with adults and children as well as bilinguals on iconic/pointing gesture production it shows that the specific language speakers use modulates the rate and the shape of the iconic gesture production of the same events. The findings challenge the claims aiming to understand gesture’s function for “thinking only” in adults and during development.

Abstract

In everyday communication speakers often refer in speech and/or gesture to objects in their immediate environment, thereby shifting their addressee's attention to an intended referent. The neurobiological infrastructure involved in the comprehension of such basic multimodal communicative acts remains unclear. In an event-related fMRI study, we presented participants with pictures of a speaker and two objects while they concurrently listened to her speech. In each picture, one of the objects was singled out, either through the speaker's index-finger pointing gesture or through a visual cue that made the object perceptually more salient in the absence of gesture. A mismatch (compared to a match) between speech and the object singled out by the speaker's pointing gesture led to enhanced activation in left IFG and bilateral pMTG, showing the importance of these areas in conceptual matching between speech and referent. Moreover, a match (compared to a mismatch) between speech and the object made salient through a visual cue led to enhanced activation in the mentalizing system, arguably reflecting an attempt to converge on a jointly attended referent in the absence of pointing. These findings shed new light on the neurobiological underpinnings of the core communicative process of comprehending a speaker's multimodal referential act and stress the power of pointing as an important natural device to link speech to objects.

Abstract

The current study examines, for the first time, the viewpoint preferences of signing children in expressing spatial relations that require imposing a viewpoint (left-right, front-behind). We elicited spatial descriptions from deaf children (4–9 years of age) acquiring Turkish Sign Language (TİD) natively from their deaf parents and from adult native signers of TİD. Adults produced these spatial descriptions from their own viewpoint and from that of their addressee depending on whether the objects were located on the lateral or the sagittal axis. TİD-acquiring children, on the other hand, described all spatial configurations from their own viewpoint. Differences were also found between children and adults in the type of linguistic devices and how they are used to express such spatial relations.

Abstract

Speakers use differential referring expressions in pragmatically appropriate ways to produce coherent narratives. Languages, however, differ in a) whether REs as arguments can be dropped and b) whether personal pronouns encode gender. We examine two languages that differ from each other in these two aspects and ask whether the co-reference context and the gender encoding options affect the use of REs differentially. We elicited narratives from Dutch and Turkish speakers about two types of three-person events, one including people of the same and the other of mixed-gender. Speakers re-introduced referents into the discourse with fuller forms (NPs) and maintained them with reduced forms (overt or null pronoun). Turkish speakers used pronouns mainly to mark emphasis and only Dutch speakers used pronouns differentially across the two types of videos. We argue that linguistic possibilities available in languages tune speakers into taking different principles into account to produce pragmatically coherent narratives

Abstract

Communication is facilitated when listeners allocate their attention to important information (focus) in the message, a process called "information structure." Linguistic cues like the preceding context and pitch accent help listeners to identify focused information. In multimodal communication, relevant information can be emphasized by nonverbal cues like beat gestures, which represent rhythmic nonmeaningful hand movements. Recent studies have found that linguistic and nonverbal attention cues are integrated independently in single sentences. However, it is possible that these two cues interact when information is embedded in context, because context allows listeners to predict what information is important. In an ERP study, we tested this hypothesis and asked listeners to view videos capturing a dialogue. In the critical sentence, focused and nonfocused words were accompanied by beat gestures, grooming hand movements, or no gestures. ERP results showed that focused words are processed more attentively than nonfocused words as reflected in an N1 and P300 component. Hand movements also captured attention and elicited a P300 component. Importantly, beat gesture and focus interacted in a late time window of 600-900 msec relative to target word onset, giving rise to a late positivity when nonfocused words were accompanied by beat gestures. Our results show that listeners integrate beat gesture with the focus of the message and that integration costs arise when beat gesture falls on nonfocused information. This suggests that beat gestures fulfill a unique focusing function in multimodal discourse processing and that they have to be integrated with the information structure of the message.

Abstract

There is a long-standing assumption that gestural forms are geared by a set of modes of representation (acting, representing, drawing, moulding) with each technique expressing speakers’ focus of attention on specific aspects of referents (Müller, 2013). Beyond different taxonomies describing the modes of representation, it remains unclear what factors motivate certain depicting techniques over others. Results from a pantomime generation task show that pantomimes are not entirely idiosyncratic but rather follow generalisable patterns constrained by their semantic category. We show that a) specific modes of representations are preferred for certain objects (acting for manipulable objects and drawing for non-manipulable objects); and b) that use and ordering of deictics and modes of representation operate in tandem to distinguish between semantically related concepts (e.g., “to drink” vs “mug”). This study provides yet more evidence that our ability to communicate through silent gesture reveals systematic ways to describe events and objects around us

Abstract

Speakers achieve coherence in discourse by alternating between differential lexical forms e.g. noun phrase, pronoun, and null form in accordance with the accessibility of the entities they refer to, i.e. whether they introduce an entity into discourse for the first time or continue referring to an entity they already mentioned before. Moreover, tracking of entities in discourse is a multimodal phenomenon. Studies show that speakers are sensitive to the informational structure of discourse and use fuller forms (e.g. full noun phrases) in speech and gesture more when re-introducing an entity while they use attenuated forms (e.g. pronouns) in speech and gesture less when maintaining a referent. However, those studies focus mainly on non-pro-drop languages (e.g. English, German and French). The present study investigates whether the same pattern holds for pro-drop languages. It draws data from adult native speakers of Turkish using elicited narratives. We find that Turkish speakers mostly use fuller forms to code subject referents in re-introduction context and the null form in maintenance context and they point to gesture space for referents more in re-introduction context compared maintained context. Hence we provide supportive evidence for the reverse correlation between the accessibility of a discourse referent and its coding in speech and gesture. We also find that, as a novel contribution, third person pronoun is used in re-introduction context only when the referent was previously mentioned as the object argument of the immediately preceding clause.

Abstract

Deaf children whose hearing losses prevent them from accessing spoken language and whose hearing parents have not exposed them to sign language develop gesture systems, called homesigns, which have many of the properties of natural language—the so-called resilient properties of language. We explored the resilience of structure built around the predicate—in particular, how manner and path are mapped onto the verb—in homesign systems developed by deaf children in Turkey and the United States. We also asked whether the Turkish homesigners exhibit sentence-level structures previously identified as resilient in American and Chinese homesigners. We found that the Turkish and American deaf children used not only the same production probability and ordering patterns to indicate who does what to whom, but also used the same segmentation and conflation patterns to package manner and path. The gestures that the hearing parents produced did not, for the most part, display the patterns found in the children's gestures. Although cospeech gesture may provide the building blocks for homesign, it does not provide the blueprint for these resilient properties of language.

Abstract

Recipients process information from speech and co-speech gestures, but it is currently unknown how this processing is influenced by the presence of other important social cues, especially gaze direction, a marker of communicative intent. Such cues may modulate neural activity in regions associated either with the processing of ostensive cues, such as eye gaze, or with the processing of semantic information, provided by speech and gesture.
Participants were scanned (fMRI) while taking part in triadic communication involving two recipients and a speaker. The speaker uttered sentences that
were and were not accompanied by complementary iconic gestures. Crucially, the speaker alternated her gaze direction, thus creating two recipient roles: addressed (direct gaze) vs unaddressed (averted gaze) recipient. The comprehension of Speech&Gesture relative to SpeechOnly utterances recruited middle occipital, middle temporal and inferior frontal gyri, bilaterally. The calcarine sulcus and posterior cingulate cortex were sensitive to differences between direct and averted gaze. Most importantly, Speech&Gesture utterances, but not SpeechOnly utterances, produced additional activity in the right middle temporal gyrus when participants were addressed. Marking communicative intent with gaze direction modulates the processing of speech–gesture utterances in cerebral areas typically associated with the semantic processing of multi-modal communicative acts.

Abstract

Hand gestures and speech form a single integrated system of meaning during language comprehension, but is gesture processed with speech in a unique fashion? We had subjects watch multimodal videos that presented auditory (words) and visual (gestures and actions on objects) information. Half of the subjects related the audio information to a written prime presented before the video, and the other half related the visual information to the written prime. For half of the multimodal video stimuli, the audio and visual information contents were congruent, and for the other half, they were incongruent. For all subjects, stimuli in which the gestures and actions were incongruent with the speech produced more errors and longer response times than did stimuli that were congruent, but this effect was less prominent for speech-action stimuli than for speech-gesture stimuli. However, subjects focusing on visual targets were more accurate when processing actions than gestures. These results suggest that although actions may be easier to process than gestures, gestures may be more tightly tied to the processing of accompanying speech.

Abstract

Languages typically express semantic components of motion events such as manner (roll) and path (down) in separate lexical items. We explore how these combinatorial possibilities of language arise by focusing on (i) gestures produced by deaf children who lack access to input from a conventional language (homesign); (ii) gestures produced by hearing adults and children while speaking; and (iii) gestures used by hearing adults without speech when asked to do so in elicited descriptions of motion events with simultaneous manner and path. Homesigners tended to conflate manner and path in one gesture, but also used a mixed form, adding a manner and/or path gesture to the conflated form sequentially. Hearing speakers, with or without speech, used the conflated form, gestured manner, or path, but rarely used the mixed form. Mixed form may serve as an intermediate structure on the way to the discrete and sequenced forms found in natural languages.

Abstract

In everyday human communication, we often express our communicative intentions by manually pointing out referents in the material world around us to an addressee, often in tight synchronization with referential speech. This study investigated whether and how the kinematic form of index finger pointing gestures is shaped by the gesturer's communicative intentions and how this is modulated by the presence of concurrently produced speech. Furthermore, we explored the neural mechanisms underpinning the planning of communicative pointing gestures and speech. Two experiments were carried out in which participants pointed at referents for an addressee while the informativeness of their gestures and speech was varied. Kinematic and electrophysiological data were recorded online. It was found that participants prolonged the duration of the stroke and poststroke hold phase of their gesture to be more communicative, in particular when the gesture was carrying the main informational burden in their multimodal utterance. Frontal and P300 effects in the ERPs suggested the importance of intentional and modality-independent attentional mechanisms during the planning phase of informative pointing gestures. These findings contribute to a better understanding of the complex interplay between action, attention, intention, and language in the production of pointing gestures, a communicative act core to human interaction.

Abstract

A fundamental property of language is that it can be used to refer to entities in the extra-linguistic physical context of a conversation in order to establish a joint focus of attention on a referent. Typological and psycholinguistic work across a wide range of languages has put forward at least two different theoretical views on demonstrative reference. Here we contrasted and tested these two accounts by investigating the electrophysiological brain activity underlying the construction of indexical meaning in comprehension. In two EEG experiments, participants watched pictures of a speaker who referred to one of two objects using speech and an index-finger pointing gesture. In contrast with separately collected native speakers’ linguistic intuitions, N400 effects showed a preference for a proximal demonstrative when speaker and addressee were in a face-to-face orientation and all possible referents were located in the shared space between them, irrespective of the physical proximity of the referent to the speaker. These findings reject egocentric proximity-based accounts of demonstrative reference, support a sociocentric approach to deixis, suggest that interlocutors construe a shared space during conversation, and imply that the psychological proximity of a referent may be more important than its physical proximity.

Abstract

Comprehension of pointing gestures is fundamental to human communication. However, the neural mechanisms
that subserve the integration of pointing gestures and speech in visual contexts in comprehension
are unclear. Here we present the results of an fMRI study in which participants watched images of an
actor pointing at an object while they listened to her referential speech. The use of a mismatch paradigm
revealed that the semantic unication of pointing gesture and speech in a triadic context recruits left
inferior frontal gyrus. Complementing previous ndings, this suggests that left inferior frontal gyrus
semantically integrates information across modalities and semiotic domains.

Abstract

The spatial affordances of the visual modality give rise to a high degree of similarity between sign languages in the spatial domain. This stands in contrast to the vast structural and semantic diversity in linguistic encoding of space found in spoken languages. However, the possibility and nature of linguistic diversity in spatial encoding in sign languages has not been rigorously investigated by systematic crosslinguistic comparison. Here, we compare locative expression in two unrelated sign languages, Turkish Sign Language (Türk İşaret Dili, TİD) and German Sign Language (Deutsche Gebärdensprache, DGS), focusing on the expression of figure-ground (e.g. cup on table) and figure-figure (e.g. cup next to cup) relationships in a discourse context. In addition to similarities, we report qualitative and quantitative differences between the sign languages in the formal devices used (i.e. unimanual vs. bimanual; simultaneous vs. sequential) and in the degree of iconicity of the spatial devices. Our results suggest that sign languages may display more diversity in the spatial domain than has been previously assumed, and in a way more comparable with the diversity found in spoken languages. The study contributes to a more comprehensive understanding of how space gets encoded in language

Abstract

For humans, the ability to communicate and use language is instantiated not only in the vocal modality but also in the visual modality. The main examples of this are sign languages and (co-speech) gestures. Sign languages, the natural languages of Deaf communities, use systematic and conventionalized movements of the hands, face, and body for linguistic expression. Co-speech gestures, though non-linguistic, are produced in tight semantic and temporal integration with speech and constitute an integral part of language together with speech. The articles in this issue explore and document how gestures and sign languages are similar or different and how communicative expression in the visual modality can change from being gestural to grammatical in nature through processes of conventionalization. As such, this issue contributes to our understanding of how the visual modality shapes language and the emergence of linguistic structure in newly developing systems. Studying the relationship between signs and gestures provides a new window onto the human ability to recruit multiple levels of representation (e.g., categorical, gradient, iconic, abstract) in the service of using or creating conventionalized communicative systems.

Abstract

Establishing and maintaining reference is a crucial part of discourse. In spoken languages, differential linguistic devices mark referents occurring in different referential contexts, that is, introduction, maintenance, and re-introduction contexts. Speakers using gestures as well as users of sign languages have also been shown to mark referents differentially depending on the referential context. This article investigates the modality-specific contribution of the visual modality in marking referential context by providing a direct comparison between sign language (German Sign Language; DGS) and co-speech gesture with speech (German) in elicited narratives. Across all forms of expression, we find that referents in subject position are referred to with more marking material in re-introduction contexts compared to maintenance contexts. Furthermore, we find that spatial modification is used as a modality-specific strategy in both DGS and German co-speech gesture, and that the configuration of referent locations in sign space and gesture space corresponds in an iconic and consistent way to the locations of referents in the narrated event. However, we find that spatial modification is used in different ways for marking re-introduction and maintenance contexts in DGS and German co-speech gesture. The findings are discussed in relation to the unique contribution of the visual modality to reference tracking in discourse when it is used in a unimodal system with full linguistic structure (i.e., as in sign) versus in a bimodal system that is a composite of speech and gesture

Abstract

Speakers can adapt their speech and co-speech gestures for
addressees. Here, we investigate whether this ability is
modulated by age. Younger and older adults participated in a
comic narration task in which one participant (the speaker)
narrated six short comic stories to another participant (the
addressee). One half of each story was known to both participants, the other half only to the speaker. Younger but
not older speakers used more words and gestures when narrating novel story content as opposed to known content.
We discuss cognitive and pragmatic explanations of these findings and relate them to theories of gesture production.

Abstract

Speakers adapt their speech and gestures in various ways for their audience. We investigated further whether they use
ostensive signals (eye gaze, ostensive speech (e.g. like this, this) or a combination of both) in relation to their gestures
when talking to different addressees, i.e., to another adult or a child in a multimodal demonstration task. While adults used
more eye gaze towards their gestures with other adults than with children, they were more likely to use combined
ostensive signals for children than for adults. Thus speakers mark the communicative relevance of their gestures with different types of ostensive signals and by taking different types of addressees into account.

Abstract

Previous research on language development shows that children are tuned early on to the language-specific semantic and syntactic encoding of events in their native language. Here we ask whether language-specificity is also evident in children's early representations in gesture accompanying speech. In a longitudinal study, we examined the spontaneous speech and cospeech gestures of eight Turkish-speaking children aged one to three and focused on their caused motion event expressions. In Turkish, unlike in English, the main semantic elements of caused motion such as Action and Path can be encoded in the verb (e.g. sok- ‘put in’) and the arguments of a verb can be easily omitted. We found that Turkish-speaking children's speech indeed displayed these language-specific features and focused on verbs to encode caused motion. More interestingly, we found that their early gestures also manifested specificity. Children used iconic cospeech gestures (from 19 months onwards) as often as pointing gestures and represented semantic elements such as Action with Figure and/or Path that reinforced or supplemented speech in language-specific ways until the age of three. In the light of previous reports on the scarcity of iconic gestures in English-speaking children's early productions, we argue that the language children learn shapes gestures and how they get integrated with speech in the first three years of life.

Abstract

In human face-to-face communication, language comprehension is a multi-modal, situated activity. However, little is known about how we combine information from different modalities during comprehension, and how perceived communicative intentions, often signaled through visual signals, influence this process. We explored this question by simulating a multi-party communication context in which a speaker alternated her gaze between two recipients. Participants viewed speech-only or speech + gesture object-related messages when being addressed (direct gaze) or unaddressed (gaze averted to other participant). They were then asked to choose which of two object images matched the speaker’s preceding message. Unaddressed recipients responded significantly more slowly than addressees for speech-only utterances. However, perceiving the same speech accompanied by gestures sped unaddressed recipients up to a level identical to that of addressees. That is, when unaddressed recipients’ speech processing suffers, gestures can enhance the comprehension of a speaker’s message. We discuss our findings with respect to two hypotheses attempting to account for how social eye gaze may modulate multi-modal language comprehension.

Abstract

Early studies investigating sign language acquisition claimed
that signs whose structures are motivated by the form of their
referent (iconic) are not favoured in language development.
However, recent work has shown that the first signs in deaf
children’s lexicon are iconic. In this paper we go a step
further and ask whether different types of iconicity modulate
learning sign-referent links. Results from a picture description
task indicate that children and adults used signs with two
possible variants differentially. While children signing to
adults favoured variants that map onto actions associated with
a referent (action signs), adults signing to another adult
produced variants that map onto objects’ perceptual features
(perceptual signs). Parents interacting with children used
more action variants than signers in adult-adult interactions.
These results are in line with claims that language
development is tightly linked to motor experience and that
iconicity can be a communicative strategy in parental input.