Presentations

Abstract

One of the most daunting tasks of a listener is to map a continuous auditory stream onto known speech sound categories and lexical items. A major issue with this mapping problem is the variability in the acoustic realizations of sound categories, both within and across speakers. Past research has suggested listeners may use various sources of information, such as lexical knowledge or visual cues (e.g., lip-reading) to recalibrate these speech categories to the current speaker. Previous studies have focused on audiovisual recalibration of consonant categories. The present study explores whether vowel categorization, which is known to show less sharply defined category boundaries, also benefit from visual cues.
Participants were exposed to videos of a speaker pronouncing one out of two vowels (Dutch vowels /e/ and /ø/), paired with audio that was ambiguous between the two vowels. The most ambiguous vowel token was determined on an individual basis by a categorization task at the beginning of the experiment. In one group of participants, this auditory token was paired with a video of an /e/ articulation, in the other group with an /ø/ video. After exposure to these videos, it was found in an audio-only categorization task that participants had adapted their categorization behavior as a function of the video exposure. The group that was exposed to /e/ videos showed a reduction of /ø/ classifications, suggesting they had recalibrated their vowel categories based on the available visual information. These results show that listeners indeed use visual information to recalibrate vowel categories, which is in line with previous work on audiovisual recalibration in consonant categories, and lexically-guided recalibration in both vowels and consonants.
In addition, a secondary aim of the current study was to explore individual variability in audiovisual recalibration. Phoneme categories vary not only in terms of boundary location, but also in terms of boundary sharpness, or how strictly categories are distinguished. The present study explores whether this sharpness is associated with the amount of audiovisual recalibration. The results tentatively support that a fuzzy boundary is associated with stronger recalibration, suggesting that listeners’ category sharpness may be related to the weight they assign to visual information in audiovisual speech perception. If listeners with fuzzy boundaries assign more weight to visual cues, given that vowel categories have less sharp boundaries than consonants, there ought to be audiovisual recalibration for vowels as well. This is exactly what was found in the current study.

Abstract

The classroom is designed to teach children cultural inventions for which the brain is not evolutionary designed. Hence the
classroom environment has to implement cultural reycling of neuronal maps. To do this effectively it has to recruit existing neural
infrastructure. Therefore, teaching programmes have to be tailored to the possibilities and limitations of available neural architecture.
An example in case is reading, a cultural invention of a few thousand years old. Orthographies and reading methods need
to use visual cortex areas in the most optimal way. I will discuss how the characteristics of different orthographies are tailored
to the possibilities of complex cells in visual cortex. In addition, different reading methods will be evaluated in the light of our
understanding of human brain organization. I will argue that a systematic investigation of culture-brain relations is much needed
for optimizing the optimal environment.

Abstract

Recent work suggests that monitoring in speech production may occur via domain-general mechanisms responsible for detecting response conflict. To test this hypothesis, we measured EEG as people engaged in both non-verbal (flanker) and verbal (tongue twisters) tasks designed to elicit response conflict and errors. In the flanker task, people pressed a button corresponding to whether a center arrow was facing left or right, and response conflict was induced with flanking arrows pointing in the same (congruent; >>>>>) or a different (incongruent >><>>) direction. In the tongue twister task, people read sequences of four nonwords three times in which rhymes alternated in an ABAB pattern while onset speech sounds alternated in an ABBA (tongue twister) or an ABAB (non-tongue twister) pattern (e.g., tif deev dif teev vs. tif teev dif deef). Results in the fl anker task showed standard markers of response conflict in the form of an increased N2 for incongruent relative to congruent trials as well as an error-related negativity (ERN) for incorrect trials. Behaviourally, more errors were elicited for tongue twisters relative to nontongue twister trials, and an ERN was observed on incorrect responses. Correlations between the magnitude of the N2 and ERN in the fl anker task with the magnitude of the ERN and error rates in the tongue twister task are consistent with a common underlying locus. Adaptation effects preceding and following erroneous trials in production are also presented. These results are consistent with response confl ict serving as a cue to monitoring in speech production.

Abstract

A central and influential idea among researchers of language is that our language faculty is organized according to the principle of strict compositionality, which implies that the meaning of an utterances is a function of the meaning of its parts and of the syntactic rules by which these parts are combined. The implication of this idea is that beyond word recognition, language interpretation takes place in a two-step fashion. First, the meaning of a sentence is computed. In a second step the sentence meaning is integrated with information from prior discourse, with world knowledge, with information about the speaker, and with semantic information from extralinguistic domains such as co-speech gestures or the visual world. FMRI results and results from recordings of event related brain potentials will be presented that are inconsistent with this classical model of language intepretation. Our data support a model in which knowledge about the context and the world, knowledge about concomitant information from other modalities, and knowledge about the speaker are brought to bear immediately, by the same fast-acting brain system that combines the meanings of individual words into a message-level representation. The Memory, Unification and Control (MUC) model provides a neurobiological plausible account of the underlying neural architecture. Resting state connectivity data, and results from Psycho-Physiological Interactions will be discussed, suggesting a division of labour between temporal and inferior frontal cortex. These results indicate that Broca’s area and adjacent cortex play an important role in semantic and syntactic unification operations. I will also discuss fMRI results that indicate the insufficiency of the Mirror Neuron Hypothesis to explain language understanding. Instead I will sketch a picture of language processing from an embrained perspective.

Abstract

From a functionalist perspective all that brain research is claimed to have told us is that language processing "happens somewhere north of the neck" (Jerry Fodor, 1999). I will argue why I disagree with this conclusion, for at least the following three reasons. First, one fundamental question in the language sciences is: what makes the human brain language-ready? Understanding the neural architecture that supports human language function is a crucial part of the explanandum. I will show some unique features of human perisylvian cortex based on data from Diffusion Tensor Imaging and resting state fMRI. The second argument is that even if one is only interested in the cognitive architecture of language comprehension and production, relevant evidence can be obtained from neurobiological data, both structural and functional. I will discuss the consequences of connectivity patterns in the brain for assumptions in processing models of language, and I will show fMRI data based on a repetition suppression paradigm that provide evidence for the claim that syntactic encoding and parsing are based on the same mechanism. Finally, I will argue that framing theories of sentence processing in a way that connects to other areas of cognitive neuroscience might be helpful in asking interesting and relevant new questions. I will illustrate this in the context of the Memory, Unification and Control (MUC) model of language.

Abstract

A central and influential idea among researchers of language is that our language faculty is organized according to the principle of strict compositionality, which implies that the meaning of an utterances is a function of the meaning of its parts and of the syntactic rules by which these parts are combined. The implication of this idea is that beyond word recognition, language interpretation takes place in a two-step fashion. First, the meaning of a sentence is computed. In a second step the sentence meaning is integrated with information from prior discourse, with world knowledge, with information about the speaker, and with semantic information from extralinguistic domains such as co-speech gestures or the visual world. FMRI results and results from recordings of event related brain potentials will be presented that are inconsistent with this classical model of language intepretation. Our data support a model in which knowledge about the context and the world, knowledge about concomitant information from other modalities, and knowledge about the speaker are brought to bear immediately, by the same fast-acting brain system that combines the meanings of individual words into a message-level representation. The Memory, Unification and Control (MUC) model provides a neurobiological plausible account of the underlying neural architecture. Resting state connectivity data, and results from Psycho-Physiological Interactions will be discussed, suggesting a division of labour between temporal and inferior frontal cortex. These results indicate that Broca’s area and adjacent cortex play an important role in semantic and syntactic unification operations. I will also discuss fMRI results that indicate the insufficiency of the Mirror Neuron Hypothesis to explain language understanding. Instead I will sketch a picture of language processing from an embrained perspective.

Abstract

Traditionally, language comprehension has been studied as a solitary and unimodal activity. Here, we investigate language comprehension as a joint activity, i.e., in a dynamic social context involving multiple participants in different roles with different perspectives, while taking into account the multimodal nature of facetoface communication. We simulated a triadic communication context involving a speaker alternating her gaze between two different recipients, conveying information not only via speech but gesture as well. Participants thus viewed videorecorded speechonly or speech+gesture utterances referencing objects (e.g., “he likes the laptop”/+TYPING ON LAPTOPgesture) when being addressed (direct gaze) or unaddressed (averted gaze). The videoclips were followed by two object images (laptoptowel). Participants’ task was to choose the object that matched the speaker’s message (i.e., laptop). Unaddressed recipients responded significantly slower than addressees for speechonly utterances. However, perceiving the same speech accompanied by gestures sped them up to levels identical to that of addressees. Thus, when speech processing suffers due to being unaddressed, gestures become more prominent and boost comprehension of a speaker’s spoken message. Our findings illuminate how participants process multimodal language and how this process is influenced by eye gaze, an important social cue facilitating coordination in the joint activity of conversation.