The role of invariant line junctions in object and visual word recognition

AbstractObject recognition relies heavily on invariant visual features such as the manner in which lines meet at vertices to form viewpoint-invariant junctions (e.g. T, L). We wondered whether these features also underlie readers’ competence for fast recognition of printed words. Since reading is far too recent to have exerted any evolutionary pressure on brain evolution, visual word recognition might be based on pre-existing mechanisms common to all visual object recognition. In a naming task, we presented partially deleted pictures of objects and printed words in which either the vertices or the line midsegments were preserved. Subjects showed an identical pattern of behavior with both objects and words: they made fewer errors and were faster to respond when vertices were preserved. Our results suggest that vertex invariants are used for object recognition and that this evolutionarily ancient mechanism is being co-opted for reading

Les événements émotionnels transitoires et les traits affectifs individuels affectent la reconnaissance des émotions dans une tâche de prise de décision perceptuelle

Les émotions forgent notre perception du monde social. Nous avons investigué comment des états affectifs transitoires et prolongés pourraient influencer la perception des émotions faciales. Des participants ont regardé des clips vidéos induisant des émotions transitoires, puis ont classifié comme effrayé ou joyeux des morphes d'expressions faciales s'étendant de la peur à la joie. Ils ont classifié davantage de visages comme effrayés après les clips négatifs, et comme joyeux après les clips positifs seulement pour les clips perçus comme les plus absorbants. Humeur négative, traits anxieux et dépressifs ont eu un effet plus fort que les émotions transitoires et ont augmenté la tendance à classifier des visages comme effrayés. Nos résultats démontrent pour la première fois que l'absorption et les dimensions temporelles des émotions influencent la perception des émotions faciales. Cette méthode permettrait de dépister une négativité prolongée et évaluer implicitement des thérapies, comme l'induction émotionnelle positive avec absorption personnalisée

Effects of emotions on social cognition

Can our emotions alter our ability to infer emotions and feel pain in others? Answering this question may shed light on human social brain functions and help avoid misunderstandings in real life. In experiment 1, participants watched joyful or fearful movie-clips, and then judged fear or joy in others based on reading about their situation. Using fMRI, we found reduced activity in brain areas implicated in mentalizing (superior temporal gyrus, precuneus, frontoparietal operculum) when others' emotions differed from those experienced by the participant. This accord with embodied accounts of affective mentalizing. In experiment 2, brain response to others' pain was reduced after watching fearful movie-clips in regions involved in empathy for pain (anterior insula). This supports a Broaden-and-build account where positive or negative affect respectively amplifies or attenuates reactivity to others. This work reveals that our emotions may dampen brain response to emotions and pain in others through different mechanisms

Influence of transient emotional episodes on affective and cognitive theory of mind

Our emotions may influence how we interact with others. Previous studies have shown an important role of emotion induction in generating empathic reactions towards others' affect. However, it remains unclear whether (and to which extent) our own emotions can influence the ability to infer people's mental states, a process associated with Theory of Mind (ToM) and implicated in the representation of both cognitive (e.g. beliefs and intentions) and affective conditions. We engaged 59 participants in two emotion-induction experiments where they saw joyful, neutral and fearful clips. Subsequently, they were asked to infer other individuals' joy, fear (affective ToM) or beliefs (cognitive ToM) from verbal scenarios. Using functional magnetic resonance imaging, we found that brain activity in the superior temporal gyrus, precuneus and sensorimotor cortices were modulated by the preceding emotional induction, with lower response when the to-be-inferred emotion was incongruent with the one induced in the observer (affective ToM). Instead, we found no effect of emotion induction on the appraisal of people's beliefs (cognitive ToM). These findings are consistent with embodied accounts of affective ToM, whereby our own emotions alter the engagement of key brain regions for social cognition, depending on the compatibility between one's own and others' affect

The good, the bad, and the suffering. Transient emotional episodes modulate the neural circuits of pain and empathy

People's sensitivity to first-hand pain is affected by their ongoing emotions, with positive states (joy, amusement) exerting analgesic-like effects, and negative states (sadness, fear) often enhancing the subjective experience. It is however less clear how empathetic responses to others' pain are affected by one's own emotional state. Following embodied accounts that posit a shared representational code between self and others' states, it is plausible that pain empathy might be influenced by emotions in the same way as first-hand pain. Alternatively, other theories in psychology suggest that social resources (including empathetic reactions) might be enhanced by positive states, but inhibited by negative states, as only in the former case, one's mindset is sufficiently broad to take into consideration others' needs. To disambiguate between these opposing predictions, we conducted two experiments in which volunteers observed positive, neutral, or negative video clips, and subsequently either received painful thermal stimuli on their own body (first-hand pain), or observed images of wounded hands (others' pain). We measured subjective pain ratings as well as physiological responses and brain activity using fMRI. We found that, contrary to the case of first-hand pain, others' pain produced weaker galvanic responses and lower neural activity in anterior insula and middle cingulate cortex following negative (relative to neutral and positive) videos. Such inhibition was partially counteracted by personal empathy traits, as individuals with higher scores retained greater sensitivity to others' pain after negative emotion induction, in both behavioral and neural responses in medial prefrontal cortex. Furthermore, multivoxel pattern analysis confirmed similar neural representation for first-hand and others' pain in anterior insula, with representation similarity increasing the more the video preceding the observation of others' suffering was positive. These findings speak against the idea that emotion induction affects first-hand and others' pain in an isomorphic way, but rather supports the idea that contrary to negative emotions, positive emotions favors a broader access to social resources

The impact of letter spacing on reading: A test of the bigram coding hypothesis

International audienceIdentifying letters and their relative positions is the basis of reading in literate adults. The Local Combinations Detector model hypothesizes that this ability results from the general organization of the visual system, whereby object encoding proceeds through a hierarchy of neural detectors that, in the case of reading, would be tuned to letters, bigrams, or other letter combinations. Given the increase of receptive fields by a factor of 2 to 3 from one neural level to the next, detectors should integrate information only for letters separated by at most 2 other characters. We test this prediction by measuring the impact of letter spacing on reading, purifying this effect from confounding variables. We establish that performance deteriorates non-linearly whenever letters are separated by at least 2 blank spaces, with the concomitant emergence of a word length effect. We then show that this cannot be reduced to an effect of physical size nor of visual eccentricity. Finally, we demonstrate that the threshold of about 2 spaces is constant across variations in font size. Those results support the hypothesis that the fast recognition of combinations of nearby letters plays a central role in the coding of words, such that interfering with this representation prevents the parallel analysis of letter strings