Publications

Abstract

This study focuses on the main work of Gilbert Ryle, “The concept of Mind” (1949). Here the author demolishes what he refers to as the cartesian dogma of “the ghost in the machine”, highlighting the absurdity of categorical ordering in dualist systems, where mental activities are explained as separate from physical actions. Surprisingly, the Italian translator of “The concept of Mind”, Ferruccio Rossi-Landi, missed this key aspect of Ryle’s work, writing up what resulted into a significantly misleading translation. This can be clearly noticed from the title already: “Lo spirito come comportamento” [The ghost as behavior]. This erroneous translation affected the interpretation of “The concept of Mind” as a mere study on behavioral reductionism in Italy. Here, I argue in favor of the originality of Ryle’s approach in pointing out the socio-cultural dynamics as the non - physical dimensions of the human mind, and yet, linked to the human brain. In doing so, I trace the crucial influence of Wittgenstein’s philosophy in Ryle’s interpretation of the concept of mind, which helps in grasping a better understanding of his work. Wittgenstein’s influence shows clearly in Ryle’s conceptual operation of grounding the acquisition of dispositions and competences - which ultimately define the rational subjects as rational agents – in the shared background of social and cultural dynamics. In a nutshell, this social dimension is the defining characteristic of the human mind and of all human actions in Ryle’s philosophy. As Ryle argues in “On thinking” (1979), this intrinsic quality of human actions can reveal itself in actions that one performs absent-mindendly in everyday life, as well as in more complex ones: for instance, when the mind reflects upon itself.

Abstract

Speaking and listening are complex tasks that we perform on a daily basis, almost without conscious effort. Interestingly, speaking almost never occurs without listening: whenever we speak, we at least hear our own speech. The research in this thesis is concerned with how the perception of our own speech influences our speaking behavior. We show that unconsciously, we actively monitor this auditory feedback of our own speech. This way, we can efficiently take action and adapt articulation when an error occurs and auditory feedback does not correspond to our expectation. Processing the auditory feedback of our speech does not, however, automatically affect speech production. It is subject to a number of constraints. For example, we do not just track auditory feedback, but also its consistency. If auditory feedback is more consistent over time, it has a stronger influence on speech production. In addition, we investigated how auditory feedback during speech is processed in the brain, using magnetoencephalography (MEG). The results suggest the involvement of a broad cortical network including both auditory and motor-related regions. This is consistent with the view that the auditory center of the brain is involved in comparing auditory feedback to our expectation of auditory feedback. If this comparison yields a mismatch, motor-related regions of the brain can be recruited to alter the ongoing articulations.

Abstract

In face-to-face communication, information from the face as well as from the voice contributes to the identification of spoken words. This dissertation investigates the time-course of the evaluation and integration of visual and auditory speech in audiovisual word identification. A large-scale audiovisual gating study extends previous research on this topic by (1) using a set of words that includes all possible initial consonants in English in three vowel contexts, (2) tracking the information processing for individual words not only across modalities, but also over time, and (3) testing quantitative models of the time-course of multimodal word recognition. There was an advantage in accuracy for audiovisual speech over auditory-only and visual-only speech. Auditory performance was, however, close to ceiling while performance on visual-only trials was near the floor of the scale, but well above chance. Visual information was used at all gates to identify the presented words. Information theoretic feature analyses of the confusion matrices revealed that the auditory signal is highly informative about voicing, manner, frication, duration, and place of articulation. Visual speech is mostly informative about place of articulation, but also about frication and duration. The auditory signal provides more information about the place of articulation for back consonants, whereas the visual signal provides more information for the labial consonants. The data were sufficient to discriminate between models of audiovisual word recognition. The Fuzzy Logical Model of Perception (FLMP; Massaro, 1998) gave a better account of the confusion matrix data than additive models of perception. A dynamic version of the FLMP was expanded to account for the evaluation and integration of information over time. This dynamic FLMP provided a better description of the data than dynamic additive competitor models. The present study builds a good foundation to investigate the role of the complex interplay between stimulus information and the structure of the lexicon. It provides an important step in building a formal representation of a lexical dynamic FLMP that can account not only for the time-course of speech information and its perceptual processing, but also for lexical influences.

Abstract

Baby's begrijpen woorden eerder dan dat ze deze zeggen. Dit stadium is onderbelicht want moeilijk waarneembaar. Caroline Junge onderzocht de vaardigheden die nodig zijn voor het leren van de eerste woordjes: conceptherkenning, woordherkenning en het verbinden van woord aan betekenis. Daarvoor bestudeerde ze de hersenpotentialen van het babybrein tijdens het horen van woordjes. Junge stelt vast dat baby's van negen maanden al woordbegrip hebben. En dat is veel vroeger dan tot nu toe bekend was. Als baby's een woord hoorde dat niet klopte met het plaatje dat ze zagen, lieten ze een N400-effect zien, een klassiek hersenpotentiaal. Uit eerder Duits onderzoek is gebleken dat baby's van twaalf maanden dit effect nog niet laten zien, omdat de hersenen nog niet rijp zouden zijn. Het onderzoek van Junge weerlegt dit. Ook laat ze zien dat als baby's goed woorden kunnen herkennen binnen zinnetjes, dit belangrijk is voor hun latere taalontwikkeling, wat mogelijk tot nieuwe therapieën voor taalstoornissen zal leiden.

Abstract

The research presented in this dissertation examined the influence of prosodically-conditioned detail on the recognition of spoken words. The main finding is that subphonemic information in the speech signal that is conditioned by constituent-level prosodic structure can affect lexical processing systematically. It was shown that such information, as indicated by and estimated from the lengthening of speech sounds in the vicinity of prosodic boundaries, can help listeners to distinguish onset-embedded words (e.g. 'ham') from longer words that have this word embedded at their onset (e.g. 'hamster'). Furthermore, it was shown that variation in the realization of a spoken word that is associated with its position in the prosodic structure of an utterance can effect lexical processing. The pattern of competitor activation associated with the recognition of a monosyllabic spoken word in utterance-final position, where the realization of the word is strongly affected by the utterance boundary, is different from that associated with the recognition of the same word in utterance-medial position, where the realization of the word is less strongly affected by the following prosodic-word boundary. Taken together, the findings attest to the extraordinary sensitivity of the spoken-word recogntion system by demonstrating the relevance for lexical processing of very fine-grained phonetic detail conditioned by prosodic structure.

Abstract

RU Radboud Universiteit Nijmegen, 16 september 2005

Abstract

Functional Magnetic Resonance Imaging (fMRI) and Electropencephalography (EEG) are the two techniques that are most often used to study the working brain. With the first technique we use the MRI machine to measure where in the brain the supply of oxygenated blood increases as result of an increased neural activity with a high precision. The temporal resolution of this measure however is limited to a few seconds. With EEG we measure the electrical activity of the brain with millisecond precision by placing electrodes on the skin of the head. We can think of the EEG signal as a signal that consists of multiple superimposed frequencies that vary their strength over time and when performing a cognitive task. Since we measure EEG at the level of the scalp, it is difficult to know where in the brain the signals exactly originate from. For about a decade we are able to measure fMRI and EEG at the same time, which possibly enables us to combine the superior spatial resolution of fMRI with the superior temporal resolution of EEG. To make this possible, we need to understand how the EEG signal is related to the fMRI signal, which is the central theme of this thesis. The main finding in this thesis is that increases in the strength of EEG frequencies below 30 Hz are related to a decrease in the fMRI signal strength, while increases in the strength of frequencies above 40 Hz is related to an increase in the strength of the fMRI signal. Changes in the strength of the low EEG frequencies are however are not coupled to changes in high frequencies. Changes in the strength of low and high EEG frequencies therefore contribute independently to changes in the fMRI signal.

Abstract

Miraña, an endangered Witotoan language spoken in the Colombian Amazon region, has an inventory of over 60 noun class markers, most of which denote the shape of nominal referents. Class markers in this language are ubiquitous in their uses for derivational purposes in nouns and for agreement marking in virtually all other nominal expressions, such as pronouns, numerals, demonstratives, and relative clauses, as well as in verbs. This study provides a comprehensive analysis of this system by giving equal attention to its morphosyntactic, semantic, and discourse-pragmatic properties. The particular properties of this system raise issues in a number of ongoing theoretical discussions, in particular the typology of systems of nominal classification and the typology of reference tracking.

Abstract

The present study examined how the updating, inhibiting, and shifting abilities underlying executive control influence spoken noun-phrase production. Previous studies provided evidence that updating and inhibiting, but not shifting, influence picture naming response time (RT). However, little is known about the role of executive control in more complex forms of language production like generating phrases. We assessed noun-phrase production using picture description and a picture-word interference procedure. We measured picture description RT to assess length, distractor, and switch effects, which were assumed to reflect, respectively, the updating, inhibiting, and shifting abilities of adult participants. Moreover, for each participant we obtained scores on executive control tasks that measured verbal and nonverbal updating, nonverbal inhibiting, and nonverbal shifting. We found that both verbal and nonverbal updating scores correlated with the overall mean picture description RTs. Furthermore, the length effect in the RTs correlated with verbal but not nonverbal updating scores, while the distractor effect correlated with inhibiting scores. We did not find a correlation between the switch effect in the mean RTs and the shifting scores. However, the shifting scores correlated with the switch effect in the normal part of the underlying RT distribution. These results suggest that updating, inhibiting, and shifting each influence the speed of phrase production, thereby demonstrating a contribution of all three executive control abilities to language production.

Abstract

Op een gemiddelde dag luisteren mensen naar spraak van heel veel verschillende mensen. Die hebben allemaal een ander stemgeluid, waardoor de woorden die zij uitspreken verschillend klinken. Luisteraars hebben daar echter weinig hinder van. Hoe is het mogelijk dat luisteraars zich zo gemakkelijk kunnen aanpassen aan verschillende sprekers? Matthias Sjerps onderzocht in zijn proefschrift een cognitief mechanisme dat luisteraars helpt om zich aan te passen aan de karakteristieken van verschillende sprekers. Hierbij maakt een luisteraar gebruik van informatie in de context. Dit mechanisme blijkt vroeg in de spraakverwerking plaats te vinden. Bovendien beïnvloedt dit mechanisme ook de perceptie van andere geluiden dan spraak. Dit laat zien dat het een zeer breed en algemeen perceptueel mechanisme betreft. Contexteffecten bleken echter sterker voor spraakgeluiden dan voor andere geluiden. Dit suggereert dat het onderzochte mechanisme, ook al is het algemeen en breed toepasbaar, versterkt kan worden door blootstelling aan taal.

Abstract

Spraakklanken, lettergrepen en woorden worden vaak minder duidelijk uitgesproken in spontane conversaties dan in formelere spreekstijlen. Dit proefschrift presenteert onderzoek naar spraakreductie in spontaan Frans en Spaans. Naar deze talen is tot nu toe weinig spraakreductieonderzoek gedaan. Er worden twee nieuwe grote corpora met spontaan Frans en Spaans beschreven. Op basis van deze corpora heb ik enkele onderzoeken gedaan waarin ik de volgende belangrijke conclusies heb getrokken. Allereerst vond ik dat akoestische data van spontane spraak waardevolle informatie kan geven over de vraag of specifieke reductiefenomenen categoriaal of continu zijn. Verder vond ik, in tegenstelling tot onderzoek naar Germaanse talen, slechts gedeeltelijk bewijs dat spraakreductie in Romaanse talen als het Frans en het Spaans beïnvloed wordt door de eigenschappen en voorspelbaarheid van het woord. Ten derde vond ik door spontaan Frans en Spaans te vergelijken dat spraakreductie tussen talen meer kan verschillen dan je zou verwachten op basis van laboratoriumonderzoek

Abstract

People with grapheme-colour synaesthesia experience colour for letters of the alphabet or digits; A can be red and B can be green. How can it be, that people automatically see a colour where only black letters are printed on the paper? With brain scans (fMRI) I showed that (black) letters activate the colour area of the brain (V4) and also a brain area that is important for combining different types of information (SPL). We found that the location where synaesthetes subjectively experience their colours is related to the order in which these brain areas become active. Some synaesthetes see their colour ‘projected onto the letter’, similar to real colour experiences, and in this case colour area V4 becomes active first. If the colours appear like a strong association without a fixed location in space, SPL becomes active first, similar to what happens for normal memories. In a last experiment we showed that in synaesthetes, attention is captured by real colour very strongly, stronger than for control participants. Perhaps this attention effect of colour can explain how letters and colours become coupled in synaesthetes.

Abstract

Marieke van der Linden investigated the neural mechanisms underlying category formation in the human brain. The research in her thesis provides novel insights in how the brain learns, stores, and uses category knowledge, enabling humans to become skilled in categorization. The studies reveal the neural mechanisms through which perceptual as well as conceptual category knowledge is created and shaped by experience. The results clearly show that neuronal sensitivity to object features is affected by categorization training. These findings fill in a missing link between electrophysiological recordings from monkey cortex demonstrating learning-induced sharpening of neuronal selectivity and brain imaging data showing category-specific representations in the human brain. Moreover, she showed that it is specifically the features of an object that are relevant for its categorization that induce selectivity in neuronal populations. Category-learning requires collaboration between many different brain areas. Together these can be seen as the neural correlates of the key points of categorization: discrimination and generalization. The occipitotemporal cortex represents those characteristic features of objects that define its category. The narrowly shape-tuned properties of this area enable fine-grained discrimination of perceptually similar objects. In addition, the superior temporal sulcus forms associations between members or properties (i.e. sound and shape) of a category. This allows the generalization of perceptually different but conceptually similar objects. Last but not least is the prefrontal cortex which is involved in coding behaviourally-relevant category information and thus enables the explicit retrieval of category membership.

Abstract

This thesis investigates the processing of words written in Japanese kanji and Chinese hànzì, i.e. logographic scripts. Special attention is given to the fact that the majority of Japanese kanji have multiple pronunciations (generally depending on the combination a kanji forms with other characters). First, using masked priming, it is established that upon presentation of a Japanese kanji multiple pronunciations are activated. In subsequent experiments using word naming with context pictures it is concluded that both Chinese hànzì and Japanese kanji are read out loud via a direct route from orthography to phonology. However, only Japanese kanji become susceptible to semantic or phonological context effects as a result of a cost due to the processing of multiple pronunciations. Finally, zooming in on the size of the articulatory planning unit in Japanese it is concluded that the mora as a phonological unit best complies with the observed data pattern and not the phoneme or the syllable

Abstract

This dissertation focuses on syntactic comprehension problems in patients with Broca's aphasia from an electrophysiological perspective. The central objective of this dissertation was to further explore what syntax-related event-related brain potential (ERP) effects can reveal about the nature of the deficit that underlies syntactic comprehension problems in patients with Broca's aphasia. Chapter two to four describe experiments in which event-related brain potentials were recorded while subjects (Broca patients, non-aphasic patients with a right-hemisphere lesion, and healthy elderly controls) were presented with sentences that contained either violations of syntactic constraints or were syntactically correct. Chapter two investigates ERP effects of subject-verb agreement violations in the different subject groups, and seeks to answer the following questions: Do agrammatic comprehenders show sensitivity to subject-verb agreement violations as indicated by a syntax-related ERP effect? In addition, does the severity of the syntactic comprehension impairment in the Broca patients affect the ERP responses? Chapter three describes an investigation of whether Broca patients show sensitivity to violations of word order as indicated by a syntax-related ERP effect, and whether the ERP responses in the Broca patients are affected by the severity of their syntactic comprehension impairment. Chapter four reports on ERP effects of violations of word-category. In addition, also a semantic violation condition was added to track possible dissociations in the sensitivity to semantic and syntactic information in the Broca patients. Chapter five describes the development of a paradigm in which the electrophysiological approach and the classical sentence-picture matching approach are combined. In this chapter, the ERP method is applied to study on-line thematic role assignment in Broca patients during sentence-picture matching. Also the relation between ERP effects and behavioral responses is pursued. Finally, Chapter 6 provides a summary of the main findings of the experiments and a general discussion.