17 décembre 2013
Laurent Mottron(U. de Montréal): "The veridical mapping model of savant abilities in autism"
Superior perception, peaks of ability, and savant skills are often observed in the autistic phenotype. The enhanced perceptual functioning model emphasizes the increased role and autonomy of perceptual information processing in autistic cognition. Autistic abilities also involve enhanced pattern detection (Mottron et al., 2006, 2009). In this presentation, we elaborate Veridical mapping a specific mechanism which can explain the higher incidence of savant abilities, as well as other related phenomena in autism. We contend that savant abilities such as hyperlexia, but also absolute pitch and synaesthesia, involve similar neurocognitive components, share the same structure and developmental course, and represent related ways by which the perceptual brain deals with objective structures under different conditions. Plausibly, these apparently different phenomena develop through a coupling of perceptual information with homological data drawn from within or across, perceptual and nonperceptual, isomorphic structures. The atypical neural connectivity characteristic of autism is consistent with a developmental predisposition to veridical mapping and the resulting high prevalence of savant abilities, absolute pitch, and synaesthesia in autism.
3 décembre 2013
Robert Daland (UCLA): "Computational modeling in phonological acquisition"
Computational modeling is playing an increasingly important role in the language sciences. The goal of this talk is to survey computational models in phonology, with a focus on what they can and can't tell us about language acquisition. The talk will open with an empirical survey of phonological acquisition, from the rudiments of rhythm to the production of morphological alternations. The central section of the talk will focus on the problem of phonotactic acquisition, and how it can be modeled computationally using a formalism known as maximum entropy harmonic grammar. The ideas will be illustrated with a case study on sonority sequencing -- the typological generalization that "good" word onsets rise in sonority, e.g. [ba] >> [bla] >> [bda] >> [lba]. In the final segment of the talk, I will discuss a problem that is well beyond the current generation of models -- the apparently concurrent development of phonetic categories, phonology, and the lexicon. I will survey the computational work that has been done on this issue, including the work I have done since I arrived at the LSCP.
26 novembre 2013
Brian Hill (IEC): "Confidence in Beliefs and Decision Making"
Intervention annulée et reportée au second semestre
The standard representation of beliefs in decision theory and much of formal epistemology, by probability measures, is incapable of representing an agent's confidence in his beliefs. However, as shall be argued in this talk, the agent's confidence in his beliefs plays, and should play, an central role in many of the most difficult decisions which we find ourselves faced with - including some that rely on (at times controversial) scientific expertise. The aim of this talk is to formulate a representation of agents' doxastic states and a (choice-theoretically grounded) theory of decision which recognises and incorporates confidence in belief. Time-permitting, some consequences for decision making in the face of radical uncertainty, and in particular the debate surrounding the Precautionary Principle, will be discussed.
19 novembre 2013
Ansgar Endress (université Pompeu Fabra, Barcelone): "Varieties of memory"
Memory comes in different varieties that each have their characteristic properties, including working memory (WM), short-term memory (STM) and long-term memory (LTM). LTM is what we store for more than, say, a minute, and has essentially unbounded storage capacity. STM is used at shorter retention intervals, but its capacity is unclear, though often assumed to be limited. WM is used to temporarily retain items that are manipulated by ongoing cognitive operations, and is thought to have a capacity of 3 or 4 items. Here, I show that the evidence for such severely capacity-limited memory stores mostly comes from experiments with substantial interference among items, and that such capacity limits are removed once interference among items is reduced. Further, I prove mathematically that, under general conditions, the presence of interference among items guarantees fixed and limited capacity limits. I also present experiments suggesting that the forms of attention that supposedly yield capacity limitations of 3 or 4 items have fundamentally different properties from memory, suggesting that they cannot be the reason for WM limitations. Based on these and other experiments, I propose a unitary view of STM, LTM and WM. With brief presentation durations, memory has a large capacity but is fleeting. When memory items are presented repeatedly or for longer durations, they become gradually stabilized into LTM representations. If proactive interference is added, memory capacity becomes compatible with past WM capacity estimates.
12 novembre 2013
Laurence Conty (Paris 8): "What is special about eye contact?"
For the last 5 decades, eye contact effects have increasingly been attracting interest in the social sciences. Indeed, perceiving a face with a direct gaze (i.e. establishing eye contact) has the power to modulate a concurrent or subsequent cognitive processing or behavior in humans. Despite the accumulation of a large body of evidence, no model exists to date, that offers a unified theory accounting for these effects. Eye contact effects have traditionally, but most often unspecifically, been explained by the high communicative value of eye contact. However, 8 years of research on the topic led me to relate them to an alternative mechanism: the eye contact’s power of self-reflection. In a recent study, my team found that direct gaze induces self-awareness, likely by focusing attentional resources on inner states. In this talk, I will try to demonstrate how this self-reflective power could account for most of the other eye contact effects reported in behavioural, physiological and neuroimaging literature. I will further question the specificity of these effects and their potential applicability for therapeutic purposes.
29 octobre 2013
Paola Escudero: "Use of phonetic detail in word learning"
I will present a series of recent studies showing the difficulties that adults and toddlers have with learning similar sounding words. An emphasis will be placed on the interrelation between sound perception and word learning/recognition and whether or not there is continuity across these two abilities. It will be shown that success in novel word learning depends on the learner’s linguistic background, the task, and the type of phonetic cues that distinguish the novel words.
15 octobre 2013
Hélène Loevenbruck (Laboratoire de Psychologie et NeuroCognition, Grenoble): "Inner speech in action: EMG data during
verbal thought and auditory verbal hallucination"
A noter, le colloquium commencera à 11h30 au lieu de 12h.
Inner speech refers to the silent production of words in one’s mind. It plays a central role in human consciousness at the interplay of language and thought and it has been described as a kind of motor action. An influential motor control model (the ‘predictive model’) claims that when motor commands are sent to the motor system to achieve an intended state, an efference copy is issued in parallel. This efference copy is used to calculate a prediction of the sensory outcome of the motor plan. It is suggested that if the actual sensory feedback matches the predicted outcome then self-authorship is experienced. This model has been extended to inner speech and it has been suggested that a defective efference copy could underlie auditory verbal hallucinations (AVH) in schizophrenia, with self-initiated covert verbal actions experienced as originating from an external cause. In this talk, I will present labial EMG data that suggest that wilful inner speech can be regarded as a kind of action and AVHs as disrupted inner speech.
1er octobre 2013
Katherine Demuth (Macquari University)
"Effects of Phonological Context on Children’s Perception and Production of Grammatical Morphemes"
Language acquisition researchers have long observed that children’s early use of grammatical morphemes is highly variable. This has generally been attributed to incomplete syntactic or semantic representations. However, recent research has found that the variable perception and production of grammatical morphemes such as articles and verbal inflections is phonologically conditioned. Thus, children are more likely to perceived and produce grammatical morphemes in simple phonological contexts than in those that are more complex. This raises many theoretical questions about the nature of linguistic representations, and how these develop. It also raises important methodological issues for investigating syntactic knowledge in L1 acquisition, bilinguals, and those with language impairment. Implications for understanding the mechanisms underlying language processing, the ‘perception-production’ gap, and a developmental model of speech planning, are discussed
Research in Paris Programme - Mairie de Paris
Ecole Normale Supérieure - Département d'études cognitives
24 septembre 2013
Antonio Rangel (Caltech, USA) "The neuroeconomics of simple choice"
Neuroeconomics seeks to characterize the computational and neurobiological basis of different types of decisions. This talk will discuss a series of studies designed to understand how the brain makes simple choices, such as whether to choose and apple or an orange, as well as the quality of the resulting decision. This includes understanding how the brain assigns value to stimuli at the time of choice, how values are compared to make a choice, how they induce the motor movements necessary to implement the choices, and how these basic processes extend to more complex choice situations.
10 septembre 2013
Mark Johnson (Macquarie University, Australia)
"Synergies in Language Acquisition"
Each human language contains an unbounded number of different sentences. How can something so large and complex possibly be learnt? Over the past two decades we've learned how to define probability distributions over grammars and the linguistic structures they generate, making it possible to define statistical models that learn regularities of complex linguistic structures. Bayesian approaches are particularly attractive because they can exploit "prior" (e.g., innate) knowledge as well as learn statistical generalizations from the input. Here we use computational models to investigate "synergies" in language acquisition, where a "joint model" is capable of solving "chicken-and-egg" problems that are challenging for conventional "staged learning" models.
Research in Paris Programme - Mairie de Paris
Ecole Normale Supérieure - Département d'études cognitives
11 juin 2013
Sarah Beck: "What counts as counterfactual thinking in children?"
The first studies on the development of counterfactual thinking focussed on one question: whether there was a shift in children's speculation about what might have been at 3-4 years of age. Since then findings from a diversity of tasks have suggested that children's abilities develop somewhat earlier (German & Nichols, 2003; Harris, 1997), later (Beck et al., 2006; Rafetseder, Cristi-Vargas, & Perner, 2010), or that the emergence of adult-like counterfactual thinking (e.g. shown by regret) might be separate from the basic reasoning abilities (e.g. Guttentag & Ferrell, 2004; Weisberg & Beck, 2010; 2012). I will explore which of the developmental data offer good evidence for counterfactual thinking and identify questions that remain.
30 avril 2013
Uriah Kriegel: "Beyond the neural correlates of consciousness".
One of the most flourishing research areas in the cognitive neuroscience of the past decade has been the search for the neural correlates of consciousness. Yet science is typically interested not only in correlation relations, but also – and more deeply – in causal and constitutive relations. When faced with a correlation between two phenomena in nature, we typically feel compelled to produce an explanation of why the two correlate. The purpose of this paper is twofold. In the first place, I want to lay out the various possible explanations of the correlation between consciousness and its neural correlate – to provide a sort of “menu” of options from which we would ultimately have to choose. Secondly, however, I want to discuss considerations suggesting that, under certain reasonable assumptions, the choice among these various options may be in principle underdetermined by the relevant scientific evidence, in the sense that the traditional metaphysical positions may be strictly empirically equivalent.
23 avril 2013
Robin Dunbar (Oxford): Why the Internet Wont Get You Any More Friends
The internet and its social networking site derivatives such as Facebook were sold to us on the promise of widening our social horizons. The internet offers us the implicit opportunity to make casual acquaintances with people all around the world, and so widen our social horizons. I shall argue that this promissory note was made without consulting the humans at the centre of it all. In fact, although the internet does solve some problems of social interaction, it does not, and cannot, cut through the glass ceiling that limits the number of relationships we can have, now known as Dunbar’s Number. This limit on the number of friendships we can maintain is a consequence partly of cognitive constraints in the human brain and partly a consequence of time constraints (in a context where relationships require the investment of time spent with the friend). However, we can still ask whether, given these constraints, the digital world might yet allow us to increase the size of our social communities by other means, and I will speculate on some of these (in particular, the role of virtual touch)
16 avril 2013
Giorgio Coricelli (Ecole Normale Supérieure, Laboratoire de Neurosciences Cognitives, Paris): “Counterfactual processing of values in private and social contexts”
In the talk I will present results from a series of experiments on the behavioral and neural correlates of counterfactual (fictive) processing of values in private and social contexts. Counterfactual evaluation means to compare the outcome of our choice with the outcome we could have gotten with a different choice. In social settings the counterfactual outcome could be the outcome of a choice taken by another individual. Neuroimaging and neuopsychological data show a neuroanatomical dissociation between private and social counterfactual processing. Thus, the orbitofrontal cortex appears to play a fundamental role in encoding counterfactual evaluations in private environments, while the medial prefrontal cortex computes social counterfactual values.
9 avril 2013
Iroise Dumontheil (UCL / ICN): What is special about social cognition?
Social cognition studies often employ tasks that involve explicitly thinking about other people’s mental states (theory of mind or mentalising). However, everyday life may require the use of theory of mind in a much more implicit and online way, as well as in combination with executive functions processes of goal management, integration of information, and action selection. Paradigms that combine executive functions and social cognition demands allow the investigation of domain-specific and domain-general behavioural and neural correlates of social and cognitive control mechanisms. I will present a series of studies highlighting the sensitivity of medial prefrontal cortex activity to the manipulation of social information, in contrast with the domain-general recruitment of lateral prefrontal and parietal cortex regions associated with increasing information integration and action selection demands.
2 avril 2013
Kenneth Harris (Imperial College, London): The Neural Marketplace
The brain consists of billions of neurons, which together form the world’s most powerful information processing machine. The fundamental principles that allow these cells to organize into computing networks are unknown. This talk will describe a hypothesis for neuronal self-organization, in which competition for retroaxonal factors causes neurons to form functional networks, through processes akin to those of a free-market economy.
Classically, neurons communicate by anterograde conduction of action potentials. However, information can also pass backward along axons, a process that is well characterized during the development of the nervous system. Recent experiments have shown that information about changes to a neuron's output synapses may pass backward along the axon, and cause changes in the same neurons inputs. Here we suggest a computational role for such "retroaxonal" signals in adult learning. We hypothesize that strengthening of a neuron’s output synapses stabilizes recent changes in the same neuron’s inputs. During learning, the input synapses of many neurons undergo transient changes, resulting in altered spiking activity. If this in turn promotes strengthening of output synapses, the recent synaptic changes will be stabilized; otherwise they will decay. A representation of sensory stimuli therefore evolves that is tailored to the demands of behavioral tasks. The talk will describe experimental evidence in support of this hypothesis, and a mathematical theory for how networks constructed along these principles can learn information-processing tasks.
26 mars 2013
Alex Cristia: "From speech to language in infancy".
Hearing children make great strides in attuning their perception to fit the ambient spoken language within the first year of life. In this process, the spoken input plays a key role, as infants growing up in Japanese-speaking communities attune to Japanese and not English. It is therefore of crucial importance to gain a good understanding of the input to language acquisition. In this talk, I summarize some of my work, approaching this problem from multiple perspectives, albeit concentrating in phonology. Corpora analyses reveal that infant-directed speech is neither uniformly hyperarticulated nor a linguistically messy, purely emotional signal. A combination of corpora analyses and perceptual experiments sheds light on the next step, how the acoustic signal is perceived by the human infant. The acoustic characteristics of individual caregivers' speech are found to predict their infants' sound discrimination, but the strength of this association is dependent on the auditory model used to describe the signal. While this bivariate association is ambiguous by definition, artificial grammars and laboratory-based exposures reveal the extent to which infants' perception is shaped by the distributions in the speech they are exposed to, but also that infants' induction can be under- and over-specific. A final research strand assesses the brain networks that are involved in infants' speech sound processing, primarily using fNIRS.
19 mars 2013
Manos Tsakiris *LAB* (Lab of Action & Body), Department of Psychology,
Royal Holloway, University of London: "Body-conscious? Yes, but in what way(s)?"
Voir le site du Lab of Action & Body
Consciousness of one’s body is intimately linked to self-identity, the sense of being “me”. A key question is how the brain integrates different sensory signals from the body to produce the experience of this body as mine. Converging evidence suggests that the integration of exteroceptive signals related to the body, such as vision and touch, produces or even alters the sense of self. For example, in the "Rubber Hand Illusion" and the more recently reported "Enfacement Illusion", watching another body being touched synchronously with one’s own produces important changes in the mental representation of one's self. However, multisensory integration conveys information about the body as perceived from the outside, and hence, represents only one channel of information available for self-awareness. Interoception, defined here as the sense of the physiological condition of the body, is an ubiquitous information channel used to represent one’s body from within. How does interoceptive information interact with exteroceptive information to produce the more general awareness of the “material me”? I will present a series of experiments that investigate this interaction and propose a model of the self that relies on the integration of the body as perceived from within and from the outside.
12 mars 2013
Maria Chait (UCL Ear Institute) : "Discovering patterns in sound sequences.".
The notion that auditory scene analysis is based on predictive processing has recently been receiving considerable attention. According to this view, the auditory system continuously seeks to make sense of incoming information by searching for regularities within the arriving acoustic signal and forming predictive models concerning future input. The formation of such models allows the system to adapt to environment statistics, conserve resources, and optimize behaviour. I will present a series of psychophysics and MEG experiments which investigate listeners' sensitivity to different forms of regularity in the context of auditory scene analysis tasks (e.g. detecting changes in the pattern of on-going sequences, segregating concurrent sequences, etc.) with the purpose of shedding light on the kinds of stimulus regularities to which we are very sensitive vs. those that are less perceptually salient.
26 février 2013
Miguel Maravall: "(DIS)ORGANIZATIONAL PRINCIPLES FOR NEURONAL RESPONSES IN THE WHISKER SYSTEM".
Rodents use their whiskers to perform demanding sensory discrimination tasks. Identifying an object's position or texture requires the system to encode temporal patterns of whisker motion fluctuations with high precision. Accordingly, neurons in the somatosensory thalamus and cortex are not just sensitive to spatial stimulus structure -e.g., motion of particular whiskers or in particular directions-, but also have clear feature selectivity (receptive fields) in the temporal domain. Here I will describe recent work in search of the principles governing this feature selectivity.
Different neurons in the barrel cortex participate heterogeneously in a given sensory task -e.g., texture discrimination. The highly variable representation across single neurons coexists with a robust code for texture at the level of small populations. The robustness of the population signal is explained by synergistic interactions between neurons carrying stronger and weaker signals; the variability across single neurons can be partly understood in terms of neurons within a given processing stage having highly diverse temporal feature selectivity. This diversity appears uncoordinated with any aspect of whisker somatotopy. As a consequence, a wide range of response properties can be sampled within a small region of barrel cortex.
Diverse temporal feature selectivity is also found in the VPM nucleus, the main thalamic relay to cortex: different VPM neurons respond to distinct stimulus features. The existence of rich, diverse population codes at both thalamic and cortical stages raises the question of how information is successfully transmitted under conditions where the heterogeneity of thalamic neurons manifests itself - i.e., where thalamic responses are not overwhelmingly synchronous. I will present ongoing work suggesting the feasibility of a mode of communication where partially synchronous thalamic activity could suffice to influence cortical neurons. Specifically, in slice experiments we have found that thalamocortical synapses have strikingly heterogeneous short-term plasticity during ongoing stimulation: each synapse responds most strongly to particular stimulation intervals, giving rise to a rich "synaptic population code" for dynamic stimuli.
5 février 2013
Vasily Klucharev (University of Basel, Department of Psychology): "Big Brother in our brain: a neurobiological mechanism of conformity".
Humans often change their beliefs or behavior due to the behavior or opinions of others. We explored, with the use of various neuroimaging methods (fMRI, TMS, ERPs), whether social conformity is an automatic process that is based on a general performance-monitoring mechanism (Klucharev et al., 2009; Klucharev et al., 2011; Shestakova et al., 2013). We hypothesized that conflicts with normative group opinion modulates activity of the dopaminergic regions often associated with performance monitoring and subsequent adjustment of behavior. Using fMRI we showed that conflicts with group opinion modulated neuronal activity in the posterior medial frontal cortex and the ventral striatum. We also demonstrated that the transient downregulation of the posterior medial frontal cortex reduced conformity. Overall, our results support the hypothesis that some forms of social influence are mediated by activity of the general performance-monitoring circuitry. Furthermore, our results suggest that social conformity is underlined by the neural error-monitoring activity which signals probably the most fundamental social mistake that of being “too different” from others.
- Klucharev V, Hytonen K, Rijpkema M, Smidts A, Fernandez G (2009) Reinforcement learning signal predicts social conformity. Neuron 61:140-151.
- Klucharev V, Munneke MA, Smidts A, Fernandez G (2011) Downregulation of the posterior medial frontal cortex prevents social conformity. J Neurosci 31:11934-11940.
- A, Rieskamp J, Tugin S, Ossadtchi A, Krutitskaya J, Klucharev V (2013) Electrophysiological precursors of social conformity. Soc Cogn Affect Neurosci.
22 janvier 2013
Anthony Movshon (NYU/CNS)
"Cortical and perceptual processing of naturalistic visual structure"
The perception of complex visual patterns emerges from neuronal activity in a cascade of areas in the primate cerebral cortex. Neurons in the primary visual cortex (V1) represent information about local orientation and spatial scale, but the role of the second visual area (V2) is enigmatic. We made synthetic images that contain complex features found in naturally occurring visual textures, and used them to stimulate macaque V1 and V2 neurons. Most V2 cells respond more vigorously to these stimuli than to matched control stimuli lacking naturalistic structure, while V1 cells do not. fMRI measurements in humans reveal differences in V1 and V2 responses to the same textures that are consistent with neuronal measurements in macaque. Finally, the ability of human observers to detect naturalistic structure is well predicted by the strength of the neuronal and fMRI responses in V2 but not in V1. These results reveal a novel and particular role for V2 in the representation of naturally occurring structure in visual images, and suggest ways that it begins the transformation of elementary visual features into the specific signals about scenes and objects that are found in areas further downstream in the visual pathway.