Publications

Abstract

Four probe latency experiments show that the ‘constituent boundary effect’ (transitions between constituents are more difficult than within constituents) is a retrieval and not a storage phenomenon. The experimental logic used is called paraphrastic reproduction: after verbatim memorization of some sentences, subjects were instructed to reproduce them both in their original wording and in the form of sentences that, whilst preserving the original meaning, embodied different syntactic constructions. Syntactic constructions are defined as pairs which consist of a pattern of conceptual information and a syntactic scheme, i.e. a sequence of syntactic word categories and function words. For example, the sequence noun + finite intransitive main verb (‘John runs’) expresses a conceptual actor-action relationship. It is proposed that for each overlearned and simple syntactic construction there exists a retrieval plan which does the following. It searches through the long-term memory information that has been designated as the conceptual content of the utterance(s) to be produced, looking for a token of its conceptual pattern. The retrieved information is then cast into the format of its syntactic scheme. The organization of such plans is held responsible for the constituent boundary effect.

Abstract

Listeners cannot recognize highly reduced word forms in isolation, but they can do so when these forms are presented in context (Ernestus, Baayen, & Schreuder, 2002). This suggests that not all possible surface forms of words have equal status in the mental lexicon. The present study shows that the reduced forms are linked to the canonical representations in the mental lexicon, and that these latter representations induce reconstruction processes. Listeners restore suffixes that are partly or completely missing in reduced word forms. A series of phoneme-monitoring experiments reveals the nature of this restoration: the basis for suffix restoration is mainly phonological in nature, but orthography has an influence as well.

Abstract

This dissertation investigates two seemingly contradictory properties of the speech perception system. On the one hand, listeners are extremely sensitive to the fine phonetic details in the speech signal. These subtle acoustic cues can reduce the temporal ambiguity between words that show initial segmental overlap, and can guide lexical activation. On the other hand, comprehension does not seem to be hampered at all by the drastic reductions that typically occur in casual speech. Complete segments, and sometimes even complete syllables, may be missing, but comprehension is seemingly unaffected. This thesis aims at elucidating how words are represented and accessed in the mental lexicon, by investigating these contradictory phenomena for the domain of morphology

Abstract

Drozd's critique of Crain & Thornton's (C&T) (1998) book Investigations in Universal Grammar (IUG) raises many issues concerning theory and experimental design within generative approaches to language acquisition. I focus here on one of the strongest theoretical claims of the Modularity Matching Model (MMM): continuity of processing. For reasons different to Drozd, I argue that the assumption is tenuous. Furthermore, I argue that the focus of the MMM and the methodological prescriptions contained in IUG are too narrow to capture language acquisition.

Abstract

Eisenberg (2002) presents data from an experiment investigating three- and four-year-old children's comprehension of restrictive relative clauses (RC). From the results she argues, contrary to Hamburger & Crain (1982), that children do not have discourse knowledge of the felicity conditions of RCs before acquiring the syntax of relativization. This note evaluates this conclusion on the basis of the methodology used, and proposes that an account of syntactic development needs to be sensitive to the real-time processing requirements acquisition places on the learner.

Abstract

Pauses during continuous speech, particularly those that occur within clauses, are thought to reflect the planning of forthcoming verbal output. We used functional Magnetic Resonance Imaging (fMRI) to examine their neural correlates. Six volunteers were scanned while describing seven Rorschach inkblots, producing 3 min of speech per inkblot. In an event-related design, the level of blood oxygenation level dependent (BOLD) contrast during brief speech pauses (mean duration 1.3 s, SD 0.3 s) during overt speech was contrasted with that during intervening periods of articulation. We then examined activity associated with pauses that occurred within clauses and pauses that occurred between grammatical junctions. Relative to articulation during speech, pauses were associated with activation in the banks of the left superior temporal sulcus (BA 39/22), at the temporoparietal junction. Continuous speech was associated with greater activation bilaterally in the inferior frontal (BA 44/45), middle frontal (BA 8) and anterior cingulate (BA 24) gyri, the middle temporal sulcus (BA 21/22), the occipital cortex and the cerebellum. Left temporal activation was evident during pauses that occurred within clauses but not during pauses at grammatical junctions. In summary, articulation during continuous speech involved frontal, temporal and cerebellar areas, while pausing was associated with activity in the left temporal cortex, especially when this occurred within a clause. The latter finding is consistent with evidence that within-clause pauses are a correlate of speech planning and in particular lexical retrieval.

Abstract

Gestures that spontaneously accompany speech convey information coordinated with the concurrent speech. There has been considerable theoretical disagreement about the process by which this informational coordination is achieved. Some theories predict that the information encoded in gesture is not influenced by how information is verbally expressed. However, others predict that gestures encode only what is encoded in speech. This paper investigates this issue by comparing informational coordination between speech and gesture across different languages. Narratives in Turkish, Japanese, and English were elicited using an animated cartoon as the stimulus. It was found that gestures used to express the same motion events were influenced simultaneously by (1) how features of motion events were expressed in each language, and (2) spatial information in the stimulus that was never verbalized. From this, it is concluded that gestures are generated from spatio-motoric processes that interact on-line with the speech production process. Through the interaction, spatio-motoric information to be expressed is packaged into chunks that are verbalizable within a processing unit for speech formulation. In addition, we propose a model of speech and gesture production as one of a class of frameworks that are compatible with the data.

Abstract

In John has left London, it is clear that the event in question, John's leaving London, has occurred in the past, for example yesterday at ten. Why is it impossible, then, to make this the event time more explicit by such an adverbial, as in Yesterday at ten, John has left London? Any solution of this puzzle crucially hinges on the meaning assigned to the perfect, and the present perfect in particular. Two such solutions, a scope solution and the 'current relevance'-solution, are discussed and shown to be inadequate. A new, strictly compositional analysis of the English perfect is suggested, and it is argued that the imcompatibility of the present perfect and most past tense adverbials has neither syntactic nor semantic reasons but follows from a simple pragmatical constraint, called here the 'position-definiteness constraint'. It is the very same constraint, which also makes an utterance such as At ten, John had left at nine pragmatically odd, even if John indeed had left at nine, and hence the utterance is true.

Abstract

This study addresses the supralexical inferential processes underlying wellformedness judgements and latencies for a specic sublexical unit that appears in Dutch compounds, the interfix. Production studies have shown that the selection of interfixes in novel Dutch compounds and the speed of
this selection is primarily determined by the distribution of interfixes in existing compounds that share the left constituent with the target compound, i.e. the ‘‘left constituent family’’. In this paper, we consider the question whether constituent families also affect wellformedness decisions of novel as well as existing Dutch compounds in comprehension. We visually presented compounds containing interfixes that were either in line with the bias of the left constituent family or not. In the case of existing compounds, we also presented variants with replaced interfixes. As in production, the bias of the left constituent family emerged as a crucial predictor for both acceptance rates and response latencies. This result supports the hypothesis that, as in production, constituent families are (co-)activated in comprehension. We argue that this co-activation is part of a supralexical inferential process, and we discuss how our data might be interpreted within sublexical and supralexical theories of morphological processing.

Abstract

This study addresses the possibility that interfixes in multiconstituent nominal compounds in German and Dutch are functional as markers of immediate constituent structure.We report a lexical statistical survey of interfixation in the lexicons of German and Dutch which shows that all interfixes of German and one interfix of Dutch are significantly more likely to appear at the major constituent boundary than expected under chance conditions. A series of experiments provides evidence that speakers of German and Dutch are sensitive to the probabilistic cues to constituent structure provided by the interfixes. Thus, our data provide evidence that probability is part and parcel of grammatical competence.

Abstract

Disruption of FOXP2, a gene encoding a forkhead-domain transcription factor, causes a severe developmental disorder of verbal communication, involving profound articulation deficits, accompanied by linguistic and grammatical impairments. Investigation of the neural basis of this disorder has been limited previously to neuroimaging of affected children and adults. The discovery of the gene responsible, FOXP2, offers a unique opportunity to explore the relevant neural mechanisms from a molecular perspective. In the present study, we have determined the detailed spatial and temporal expression pattern of FOXP2 mRNA in the developing brain of mouse and human. We find expression in several structures including the cortical plate, basal ganglia, thalamus, inferior olives and cerebellum. These data support a role for FOXP2 in the development of corticostriatal and olivocerebellar circuits involved in motor control. We find intriguing concordance between regions of early expression and later sites of pathology suggested by neuroimaging. Moreover, the homologous pattern of FOXP2/Foxp2 expression in human and mouse argues for a role for this gene in development of motor-related circuits throughout mammalian species. Overall, this study provides support for the hypothesis that impairments in sequencing of movement and procedural learning might be central to the FOXP2-related speech and language disorder.

Abstract

Mental imagery is a cognitive process crucial to human reasoning. Numerous studies have characterized specific
instances of this cognitive ability, as evoked by visual imagery (VI) or motor imagery (MI) tasks. However, it
remains unclear which neural resources are shared between VI and MI, and which are exclusively related to MI.
To address this issue, we have used fMRI to measure human brain activity during performance of VI and MI
tasks. Crucially, we have modulated the imagery process by manipulating the degree of mental rotation necessary
to solve the tasks. We focused our analysis on changes in neural signal as a function of the degree of mental
rotation in each task.

Abstract

Chronic fatigue syndrome (CFS) is characterized by a debilitating fatigue of unknown aetiology. Patients who suffer from CFS report a variety of physical complaints as well as neuropsychological complaints. Therefore, it is conceivable that the CNS plays a role in the pathophysiology of CFS. The purpose of this study was to investigate neural correlates of CFS, and specifically whether there exists a linkage between disturbances in the motor system and CFS. We measured behavioural performance and cerebral activity using rapid event-related functional MRI in 16 CFS patients and 16 matched healthy controls while they were engaged in a motor imagery task and a control visual imagery task. CFS patients were considerably slower on performance of both tasks, but the increase in reaction time with increasing task load was similar between the groups. Both groups used largely overlapping neural resources. However, during the motor imagery task, CFS patients evoked stronger responses in visually related structures. Furthermore, there was a marked between-groups difference during erroneous performance. In both groups, dorsal anterior cingulate cortex was specifically activated during error trials. Conversely, ventral anterior cingulate cortex was active when healthy controls made an error, but remained inactive when CFS patients made an error. Our results support the notion that CFS may be associated with dysfunctional motor planning. Furthermore, the between-groups differences observed during erroneous performance point to motivational disturbances as a crucial component of CFS.

Abstract

Investigations of left hand praxis in imitation and object use in patients with callosal disconnection have yielded divergent results, inducing a debate between two theoretical positions. Whereas Liepmann suggested that the left hemisphere is motor dominant, others maintain that both hemispheres have equal motor competences and propose that left hand apraxia in patients with callosal disconnection is secondary to left hemispheric specialization for language or other task modalities. The present study aims to gain further insight into the motor competence of the right hemisphere by investigating pantomime of object use in split-brain patients. Three patients with complete callosotomy and, as control groups, five patients with partial callosotomy and nine healthy subjects were examined for their ability to pantomime object use to visual object presentation and demonstrate object manipulation. In each condition, 11 objects were presented to the subjects who pantomimed or demonstrated the object use with either hand. In addition, six object pairs were presented to test bimanual coordination. Two independent raters evaluated the videotaped movement demonstrations. While object use demonstrations were perfect in all three groups, the split-brain patients displayed apraxic errors only with their left hands in the pantomime condition. The movement analysis of concept and execution errors included the examination of ipsilateral versus contralateral motor control. As the right hand/left hemisphere performances demonstrated retrieval of the correct movement concepts, concept errors by the left hand were taken as evidence for right hemisphere control. Several types of execution errors reflected a lack of distal motor control indicating the use of ipsilateral pathways. While one split-brain patient controlled his left hand predominantly by ipsilateral pathways in the pantomime condition, the error profile in the other two split-brain patients suggested that the right hemisphere controlled their left hands. In the object use condition, in all three split-brain patients fine-graded distal movements in the left hand indicated right hemispheric control. Our data show left hand apraxia in split-brain patients is not limited to verbal commands, but also occurs in pantomime to visual presentation of objects. As the demonstration with object in hand was unimpaired in either hand, both hemispheres must contain movement concepts for object use. However, the disconnected right hemisphere is impaired in retrieving the movement concept in response to visual object presentation, presumably because of a deficit in associating perceptual object representation with the movement concepts.

Abstract

Since some patients with right hemisphere damage or with spontaneous callosal disconnection neglect the left half of space, it has been suggested that the left cerebral hemisphere predominantly attends to the right half of space. However, clinical investigations of patients having undergone surgical callosal section have not shown neglect when the hemispheres are tested separately. These observations question the validity of theoretical models that propose a left hemispheric specialisation for attending to the right half of space. The present study aims to investigate neglect and the use of space by either hand in gestural demonstrations in three split-brain patients as compared to five patients with partial callosotomy and 11 healthy subjects. Subjects were asked to demonstrate with precise gestures and without speaking the content of animated scenes with two moving objects. The results show that in the absence of primary perceptual or representational neglect, split-brain patients neglect left personal space in right-handed gestural demonstrations. Since this neglect of left personal space cannot be explained by directional or spatial akinesia, it is suggested that it originates at the conceptual level, where the spatial coordinates for right-hand gestures are planned. The present findings are at odds with the position that the separate left hemisphere possesses adequate mechanisms for acting in both halves of space and neglect results from right hemisphere suppression of this potential. Rather, the results provide support for theoretical models that consider the left hemisphere as specialised for processing the right half of space during the execution of descriptive gestures.

Abstract

The present study investigates the hand choice in iconic gestures that accompany speech. In 10 right-handed subjects gestures were elicited by verbal narration and by silent gestural demonstrations of animations with two moving objects. In both conditions, the left-hand was used as often as the right-hand to display iconic gestures. The choice of the right- or left-hands was determined by semantic aspects of the message. The influence of hemispheric language lateralization on the hand choice in co-speech gestures appeared to be minor. Instead, speaking seemed to induce a sequential organization of the iconic gestures.

Abstract

How can one conceive of the neuronal implementation of the processing model we proposed in our target article? In his commentary (Pulvermüller 1999, reprinted here in this issue), Pulvermüller makes various proposals concerning the underlying neural mechanisms and their potential localizations in the brain. These proposals demonstrate the compatibility of our processing model and current neuroscience. We add further evidence on details of localization based on a recent meta-analysis of neuroimaging studies of word production (Indefrey & Levelt 2000). We also express some minor disagreements with respect to Pulvermüller’s interpretation of the “lemma” notion, and concerning his neural modeling of phonological code retrieval. Branigan & Pickering discuss important aspects of syntactic encoding, which was not the topic of the target article. We discuss their well-taken proposal that multiple syntactic frames for a single verb lemma are represented as independent nodes, which can be shared with other verbs, such as accounting for syntactic priming in speech production. We also discuss how, in principle, the alternative multiple-frame-multiplelemma account can be tested empirically. The available evidence does not seem to support that account.

Abstract

During the second half of the 19th century, the psychology of language was invented as a discipline for the sole purpose of explaining the evolution of spoken language. These efforts culminated in Wilhelm Wundt’s monumental Die Sprache of 1900, which outlined the psychological mechanisms involved in producing utterances and considered how these mechanisms could have evolved. Wundt assumes that articulatory movements were originally rather arbitrary concomitants of larger, meaningful expressive bodily gestures. The sounds such articulations happened to produce slowly acquired the meaning of the gesture as a whole, ultimately making the gesture superfluous. Over a century later, gestural theories of language origins still abound. I argue that such theories are unlikely and wasteful, given the biological, neurological and genetic evidence.

Abstract

Originally published in Cognition International Journal of Cognitive Science, Volume 42, Numbers 1-3, 1992 This paper introduces a special issue of Cognition 011 lexical access in speech production. Over the last quarter century, the psycholinguistic study of speaking, and in particular of accessing words in speech, received a major new impetus from the analysis of speech errors, dysfluencies and hesMions, from aphasiology, and from new paradigms in reaction time research. The emerging theoretical picture partitions the accessing process into two subprocesses, the selection of an appropriate lexical item (and "lemma") from the mental lexicon, and the phonological encoding of that item, that is, the computation of a phonetic program for the item in the context of utterance These two theoretical domains are successively introduced by outlining some core issues that have been or still have to be addressed. The final section discusses the controversial question whether phonological encoding can affect lexical selection. This partitioning is also followed in this special issue as a whole. There are, first, four papers on lexical selection, then three papers on phonological encoding, and finally one on the interaction between selection and phonological encoding.

Abstract

This paper introduces a special issue of Cognition on lexical access in speech production. Over the last quarter century, the psycholinguistic study of speaking, and in particular of accessing words in speech, received a major new impetus from the analysis of speech errors, dysfluencies and hesitations, from aphasiology, and from new paradigms in reaction time research. The emerging theoretical picture partitions the accessing process into two subprocesses, the selection of an appropriate lexical item (a “lemma”) from the mental lexicon, and the phonological encoding of that item, that is, the computation of a phonetic program for the item in the context of utterance. These two theoretical domains are successively introduced by outlining some core issues that have been or still have to be addressed. The final section discusses the controversial question whether phonological encoding can affect lexical selection. This partitioning is also followed in this special issue as a whole. There are, first, four papers on lexical selection, then three papers on phonological encoding, and finally one on the interaction between selection and phonological encoding.

Abstract

In this paper we report on four experiments in which we attempted to prime the stress position of Dutch bisyllabic target nouns. These nouns, picture names, had stress on either the first or the second syllable. Auditory prime words had either the same stress as the target or a different stress (e.g., WORtel – MOtor vs. koSTUUM – MOtor; capital letters indicate stressed syllables in prime – target pairs). Furthermore, half of the prime words were semantically related, the other half were unrelated. In none of the experiments a stress priming effect was found. This could mean that stress is not stored in the lexicon. An additional finding was that targets with initial stress had a faster response than targets with a final stress. We hypothesize that bisyllabic words with final stress take longer to be encoded because this stress pattern is irregular with respect to the lexical distribution of bisyllabic stress patterns, even though it can be regular in terms of the metrical stress rules of Dutch.

Abstract

Formerly published in: Cognition : international journal of cognitive science, vol. 42, nos. 1-3, 1992

Abstract

In his paper, MacKay reviews his Node Structure theory of error detection, but precedes it with a critical discussion of the Perceptual Loop theory of self-monitoring proposed in Levelt (1983, 1989). The present commentary is concerned with this latter critique and shows that there are more than casual problems with MacKay’s argumentation.

Abstract

This questionnaire is designed to explore how spatial relations are encoded in Australian language, but may be of interest to researchers further afield.

Abstract

This questionnaire is designed to explore how spatial relations are encoded in Australian language, but may be of interest to researchers further afield.