Publications

Abstract

Natural conversations are characterized by short transition times between turns. This holds in particular for multi-party conversations. The short turn transitions in everyday conversations contrast sharply with the much longer speech onset latencies observed in laboratory studies where speakers respond to spoken utterances. There are many factors that facilitate speech production in conversational compared to laboratory settings. Here we highlight one of them, the impact of competition for turns. In multi-party conversations, speakers often compete for turns. In quantitative corpus analyses of multi-party conversation, the fastest response determines the recorded turn transition time. In contrast, in dyadic conversations such competition for turns is much less likely to arise, and in laboratory experiments with individual participants it does not arise at all. Therefore, all responses tend to be recorded. Thus, competition for turns may reduce the recorded mean turn transition times in multi-party conversations for a simple statistical reason: slow responses are not included in the means. We report two studies illustrating this point. We first report the results of simulations showing how much the response times in a laboratory experiment would be reduced if, for each trial, instead of recording all responses, only the fastest responses of several participants responding independently on the trial were recorded. We then present results from a quantitative corpus analysis comparing turn transition times in dyadic and triadic conversations. There was no significant group size effect in question-response transition times, where the present speaker often selects the next one, thus reducing competition between speakers. But, as predicted, triads showed shorter turn transition times than dyads for the remaining turn transitions, where competition for the floor was more likely to arise. Together, these data show that turn transition times in conversation should be interpreted in the context of group size, turn transition type, and social setting.

Abstract

-* indicates joint senior authors - Parkinson’s disease impairs motor function and cognition, which together affect language and
communication. Co-speech gestures are a form of language-related actions that provide imagistic
depictions of the speech content they accompany. Gestures rely on visual and motor imagery, but
it is unknown whether gesture representations require the involvement of intact neural sensory
and motor systems. We tested this hypothesis with a fine-grained analysis of co-speech action
gestures in Parkinson’s disease. 37 people with Parkinson’s disease and 33 controls described
two scenes featuring actions which varied in their inherent degree of bodily motion. In addition
to the perspective of action gestures (gestural viewpoint/first- vs. third-person perspective), we
analysed how Parkinson’s patients represent manner (how something/someone moves) and path
information (where something/someone moves to) in gesture, depending on the degree of bodily
motion involved in the action depicted. We replicated an earlier finding that people with
Parkinson’s disease are less likely to gesture about actions from a first-person perspective – preferring instead to depict actions gesturally from a third-person perspective – and show that
this effect is modulated by the degree of bodily motion in the actions being depicted. When
describing high motion actions, the Parkinson’s group were specifically impaired in depicting
manner information in gesture and their use of third-person path-only gestures was significantly
increased. Gestures about low motion actions were relatively spared. These results inform our
understanding of the neural and cognitive basis of gesture production by providing
neuropsychological evidence that action gesture production relies on intact motor network
function.

Abstract

In a conversation, recognising the speaker’s social action (e.g., a request) early may help the potential following speakers understand the intended message quickly, and plan a timely response. Human language is multimodal, and several studies have demonstrated the contribution of the body to communication. However, comparatively few studies have investigated (non-emotional) conversational facial signals and very little is known about how they contribute to the communication of social actions. Therefore, we investigated how facial signals map onto the expressions of two fundamental social actions in conversations: asking questions and providing responses. We studied the distribution and timing of 12 facial signals across 6778 questions and 4553 responses, annotated holistically in a corpus of 34 dyadic face-to-face Dutch conversations. Moreover, we analysed facial signal clustering to find out whether there are specific combinations of facial signals within questions or responses. Results showed a high proportion of facial signals, with a qualitatively different distribution in questions versus responses. Additionally, clusters of facial signals were identified. Most facial signals occurred early in the utterance, and had earlier onsets in questions. Thus, facial signals may critically contribute to the communication of social actions in conversation by providing social action-specific visual information.

Abstract

It is now widely accepted that the brunt of animal communication is conducted via several modalities, e.g. acoustic and visual, either simultaneously or sequentially. This is a laudable multimodal turn relative to traditional accounts of temporal aspects of animal communication which have focused on a single modality at a time. However, the fields that are currently contributing to the study of multimodal communication are highly varied, and still largely disconnected given their sole focus on a particular level of description or their particular concern with human or non-human animals. Here, we provide an integrative overview of converging findings that show how multimodal processes occurring at neural, bodily, as well as social interactional levels each contribute uniquely to the complex rhythms that characterize communication in human and non-human animals. Though we address findings for each of these levels independently, we conclude that the most important challenge in this field is to identify how processes at these different levels connect.

Abstract

This study investigates the effectiveness of training preschoolers in order to enhance their social cognition and pragmatic skills. Eighty-three 3–4-year-olds were divided into three groups and listened to stories enriched with mental state terms. Then, whereas the control group engaged in non-reflective activities, the two experimental groups were guided by a trainer to reflect on mental states depicted in the stories. In one of these groups, the children were prompted to not only talk about these states but also “embody” them through prosodic and gestural cues. Results showed that while there were no significant effects on Theory of Mind, emotion understanding, and mental state verb comprehension, the experimental groups significantly improved their pragmatic skill scores pretest-to-posttest. These results suggest that interactional interventions can contribute to preschoolers’ pragmatic development, demonstrate the value of the new embodied training, and highlight the importance of multidimensional testing for the evaluation of intervention effects.

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

During natural conversation, people must quickly understand the meaning of what the other speaker is saying. This concerns not just the semantic content of an utterance, but also the social action (i.e., what the utterance is doing—requesting information, offering, evaluating, checking mutual understanding, etc.) that the utterance is performing. The multimodal nature of human language raises the question of whether visual signals may contribute to the rapid processing of such social actions. However, while previous research has shown that how we move reveals the intentions underlying instrumental actions, we do not know whether the intentions underlying fine-grained social actions in conversation are also revealed in our bodily movements. Using a corpus of dyadic conversations combined with manual annotation and motion tracking, we analyzed the kinematics of the torso, head, and hands during the asking of questions. Manual annotation categorized these questions into six more fine-grained social action types (i.e., request for information, other-initiated repair, understanding check, stance or sentiment, self-directed, active participation). We demonstrate, for the first time, that the kinematics of the torso, head and hands differ between some of these different social action categories based on a 900 ms time window that captures movements starting slightly prior to or within 600 ms after utterance onset. These results provide novel insights into the extent to which our intentions shape the way that we move, and provide new avenues for understanding how this phenomenon may facilitate the fast communication of meaning in conversational interaction, social action, and conversation

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

Natural human interaction involves the fast-paced exchange of speaker turns. Crucially, if a next speaker waited with planning their turn until the current speaker was finished, language production models would predict much longer turn transition times than what we observe. Next speakers must therefore prepare their turn in parallel to listening. Visual signals likely play a role in this process, for example by helping the next speaker to process the ongoing utterance and thus prepare an appropriately-timed response.

To understand how visual signals contribute to the timing of turn-taking, and to move beyond the mostly qualitative studies of gesture in conversation, we examined unconstrained, computer-mediated conversations between 20 pairs of participants while systematically manipulating speaker visibility. Using motion tracking and manual gesture annotation, we assessed 1) how visibility affected the timing of turn transitions, and 2) whether use of co-speech gestures and 3) the communicative kinematic features of these gestures were associated with changes in turn transition timing.

We found that 1) decreased visibility was associated with less tightly timed turn transitions, and 2) the presence of gestures was associated with more tightly timed turn transitions across visibility conditions. Finally, 3) structural and salient kinematics contributed to gesture’s facilitatory effect on turn transition times.

Our findings suggest that speaker visibility--and especially the presence and kinematic form of gestures--during conversation contributes to the temporal coordination of conversational turns in computer-mediated settings. Furthermore, our study demonstrates that it is possible to use naturalistic conversation and still obtain controlled results.

Abstract

Methods
The present study provides a systematic analysis of co-speech gestures which spontaneously accompany the description of actions in a group of PD patients (N = 23, Hoehn and Yahr Stage III or less) and age-matched healthy controls (N = 22). The analysis considers different co-speech gesture types, using established classification schemes from the field of gesture research. The analysis focuses on the rate of these gestures as well as on their qualitative nature. In doing so, the analysis attempts to overcome several methodological shortcomings of research in this area.
Results
Contrary to expectation, gesture rate was not significantly affected in our patient group, with relatively mild PD. This indicates that co-speech gestures could compensate for speech problems. However, while gesture rate seems unaffected, the qualitative precision of gestures representing actions was significantly reduced.
Conclusions
This study demonstrates the feasibility of carrying out fine-grained, detailed analyses of gestures in PD and offers insights into an as yet neglected facet of communication in patients with PD. Based on the present findings, an important next step is the closer investigation of the qualitative changes in gesture (including different communicative situations) and an analysis of the heterogeneity in co-speech gesture production in PD.

Abstract

Mimicry has been observed regarding a range of nonverbal behaviors, but only recently have researchers started to investigate mimicry in co-speech gestures. These gestures are considered to be crucially different from other aspects of nonverbal behavior due to their tight link with speech. This study provides evidence of mimicry in co-speech gestures in face-to-face dialogue, the most common forum of everyday talk. In addition, it offers an analysis of the functions that mimicked co-speech gestures fulfill in the collaborative process of creating a mutually shared understanding of referring expressions. The implications bear on theories of gesture production, research on grounding, and the mechanisms underlying behavioral mimicry.

Abstract

This study uses a classical referential communication task to
investigate the role of co-speech gestures in the process of
coordination. The study manipulates both the common ground between the interlocutors, as well as the visibility of the gestures they use. The findings show that co-speech gestures are an integral part of the referential utterances speakers
produced with regard to both initial references as well as repeated references, and that the availability of gestures appears to impact on interlocutors’ referential oordination. The results are discussed with regard to past research on
common ground as well as theories of gesture production.

Abstract

There is evidence that co-speech gestures communicate information to addressees and that they are often communicatively intended. However, we still know comparatively little about the role of gestures in the actual process of communication. The present study offers a systematic investigation of speakers’ gesture use before and after addressee feedback. The findings show that when speakers responded to addressees’ feedback gesture rate remained constant when this feedback encouraged clarification, elaboration or correction. However, speakers gestured proportionally less often after feedback when providing confirmatory responses. That is, speakers may not be drawing on gesture in response to addressee feedback per se, but particularly with responses that enhance addressees’ understanding. Further, the large majority of speakers’ gestures changed in their form. They tended to be more precise, larger, or more visually prominent after feedback. Some changes in gesture viewpoint were also observed. In addition, we found that speakers used deixis in speech and gaze to increase the salience of gestures occurring in response to feedback. Speakers appear to conceive of gesture as a useful modality in redesigning utterances to make them more accessible to addressees. The findings further our understanding of recipient design and co-speech gestures in face-to-face dialogue.
Highlights

► Gesture rate remains constant in response to addressee feedback when the response aims to correct or clarify understanding. ► But gesture rate decreases when speakers provide confirmatory responses to feedback signalling correct understanding. ► Gestures are more communicative in response to addressee feedback, particularly in terms of precision, size and visual prominence. ► Speakers make gestures in response to addressee feedback more salient by using deictic markers in speech and gaze.

Abstract

Theorists of language have argued that co-­speech hand gestures are an
intentional part of social communication. The present study provides evidence for these
claims by showing that speakers adjust their gesture use according to their perceived relevance to the audience. Participants were asked to read about items that were and were not useful in a wilderness survival scenario, under the pretense that they would then
explain (on camera) what they learned to one of two different audiences. For one audience (a group of college students in a dormitory orientation activity), the stakes of successful
communication were low;; for the other audience (a group of students preparing for a
rugged camping trip in the mountains), the stakes were high. In their explanations to the camera, participants in the high stakes condition produced three times as many
representational gestures, and spent three times as much time gesturing, than participants in the low stakes condition. This study extends previous research by showing that the anticipated consequences of one’s communication—namely, the degree to which information may be useful to an intended recipient—influences speakers’ use of gesture.

Abstract

Common ground is an essential prerequisite for coordination in social interaction, including language use. When referring back to a referent in discourse, this referent is ‘given information’ and therefore in the interactants’ common ground. When a referent is being referred to for the first time, a speaker introduces ‘new information’. The analyses reported here are on gestures that accompany such references when they include definite and indefinite grammatical determiners. The main finding from these analyses is that referents referred to by definite and indefinite articles were equally often accompanied by gesture, but speakers tended to accompany definite references with gestures focusing on action information and indefinite references with gestures focusing on entity information. The findings suggest that speakers use speech and gesture together to design utterances appropriate for speakers with whom they share common ground.