Biology subjects

Abassi, E.

Publications and source records attributed to Abassi, E..

4 recordsLinked to original sources

bioRxiv2024

Influence of social and semantic contexts in processing speech in noise

Social interactions occupy a significant part of life, and understanding others conversations is key to navigating our social world. While the role of semantics in speech comprehension is well-established at the word or sentence level, its influence on larger conversational scales, alongside social context, is less understood. The present study examined how semantic and social contexts modulate phonetic encoding during natural conversations using a speech-in-noise paradigm. Participants listened to AI-generated dialogues (two speakers) or monologues (one speaker) in an intact or sentence-scrambled order. Each trial contained five sentences, with the fifth sentence embedded in multi-talker babble noise. The same sentence was then repeated without noise, with one word either altered or unchanged. Healthy adults identified whether the sentence matched the in-noise version. Through several online experiments (N=211), both social and semantic contexts showed influences on speech-in-noise processing, with improved performance for dialogues over monologues and for intact over sentence-scrambled conversations. These results suggest that both semantic and social factors shape speech comprehension, emphasizing their role in auditory cognition. This finding raises important questions about predictive and other mechanisms involved in processing complex, multi-sentence conversations, underscoring the critical role of social interaction in communication.

neuroscience↗

bioRxiv2021

Behavioral and neural markers of social vision

Research on face perception has revealed highly specialized visual mechanisms such as configural processing, and provided markers of interindividual differences -including disease risks and alterations- in visuoperceptual abilities that traffic in social cognition. Is face perception unique in degree or kind of mechanisms, and in its relevance for social cognition? Combining functional MRI and behavioral methods, we address the processing of an uncharted class of socially relevant stimuli: minimal social scenes involving configurations of two bodies spatially close and face-to-face as if interacting (hereafter, facing dyads). We report category-specific activity for facing (vs. non-facing) two-body configurations in selective areas of the visual cortex. That activity shows face-like signatures of configural processing -i.e., stronger response, and greater susceptibility to stimulus inversion for facing (vs. non-facing) dyads-, and is predicted by performance-based measures of body-dyad perception (i.e., accuracy in a fast visual categorization task). Moreover, individual performance in body-dyad perception is reliable, stable-over-time and correlated with the individual social sensitivity, coarsely captured by the Autism-Spectrum Quotient. Further analyses clarify the relationship between single-body and body-dyad perception. We propose that facing dyads are processed through highly specialized mechanisms (and brain areas), analogously to other biologically/socially relevant stimuli such as faces. Like face perception, facing-dyad perception can reveal basic visual processes that lay the foundations for understanding others, their relationships and interactions. Significance statementWith its specialization to faces and biological motion, vision houses the foundations of human social ability. Using a multimodal approach (meta-analysis, fMRI, visual-perception tasks and self-administered survey), we introduce a new class of visual stimuli -minimal social scenes with two face-to-face bodies-, whose processing highlights new behavioral and neural markers of visuoperceptual abilities that traffic in social cognition. Behavioral and neural effects of body-dyad perception reveal the recruitment of specialized configural processing, previously described for face perception. Furthermore, individual performance in body-dyad perception is stable over time, and predicts an individuals social sensitivity, measured in terms of autism-spectrum traits. Thus, body-dyad perception reveals uncharted aspects of visual functioning and specialization, which may critically contribute to human social life.

neuroscience↗

bioRxiv2021

Visual object categorization in infancy

Humans make sense of the world by organizing things into categories. When and how does this process begin? We investigated whether real-world object categories that spontaneously emerge in the first months of life match categorical representations of objects in the human visual cortex. Taking infants looking times as a measure of similarity, we defined a representational space where each object was defined in relation to others of the same or different categories. This space was compared with hypothesis-based and fMRI-based models of visual-object categorization in the adults visual cortex. Analyses across different age groups revealed an incremental process with two milestones. Between 4 and 10 months, visual exploration guided by saliency gives way to an organization according to the animate-inanimate distinction. Between 10 and 19 months, a category spurt leads towards a mature organization. We propose that these changes underlie the coupling between seeing and thinking in the developing mind.

neuroscience↗

bioRxiv2019

Seeing relationships: The specialization for a two-body shape in human visual perception

Human social nature has shaped visual perception. A signature of the relationship between vision and sociality is a particular visual sensitivity to social entities such as faces and bodies. We asked whether human vision also exhibits a special sensitivity to spatial relations that reliably correlate with social relations. In general, interacting people are more often situated face-to-face than back-to-back. Using functional MRI and behavioral measures in female and male human participants, we show that visual sensitivity to social stimuli extends to images including two bodies facing toward (vs. away from) each other. In particular, the inferior lateral occipital cortex, which is involved in visual-object perception, is organized such that the inferior portion encodes the number of bodies (one vs. two) and the superior portion is selectively sensitive to the spatial relation between bodies (facing vs. non-facing). Moreover, functionally localized, body-selective visual cortex responded to facing bodies more strongly than identical, but non-facing, bodies. In this area, multivariate pattern analysis revealed an accurate representation of body dyads with sharpening of the representation of single-body postures in facing dyads, which demonstrates an effect of visual context on the perceptual analysis of a body. Finally, the cost of body inversion (upside-down rotation) on body recognition, a behavioral signature of a specialized mechanism for body perception, was larger for facing vs. non-facing dyads. Thus, spatial relations between multiple bodies are encoded in regions for body perception and affect the way in which bodies are processed. Public Significance StatementHuman social nature has shaped visual perception. Here, we show that human vision is not only attuned to socially relevant entities, such as bodies, but also to socially relevant spatial relations between those entities. Body-selective regions of visual cortex respond more strongly to multiple bodies that appear to be interacting (i.e., face-to-face), relative to unrelated bodies, and more accurately represent single body postures in interacting scenarios. Moreover, recognition of facing bodies is particularly susceptible to perturbation by upside-down rotation, indicative of a particular visual sensitivity to the canonical appearance of facing bodies. This encoding of relations between multiple bodies in areas for body-shape recognition suggests that the visual context in which a body is encountered deeply affects its perceptual analysis.

neuroscience↗