Author : Anne-Raphaëlle Richoz
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (17 download)
Book Synopsis Vers la Compréhension Du Traitement Dynamique Du Visage Humain by : Anne-Raphaëlle Richoz
Download or read book Vers la Compréhension Du Traitement Dynamique Du Visage Humain written by Anne-Raphaëlle Richoz and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The human visual system is steadily stimulated by dynamic cues. Faces provide crucial information important for adapted social interactions. From an evolutionary perspective, humans have been more extensively exposed to dynamic faces, as static face images have only appeared recently with the advent of photography and the expansion of digital tools. Yet, most studies investigating face perception have relied on static faces and only a little is known about the mechanisms involved in dynamic face processing.To clarify this issue, this thesis aimed to use dynamic faces to investigate different aspects of face processing in different populations and age groups. In Study 1, we used dynamic faces to investigate whether the ability of infants aged 6, 9, and 12 months in matching audible and visible attributes of gender is influenced by the use of adult-directed (ADS) vs. infant-directed (IDS) speech. Our results revealed that from 6 months of age, infants matched female faces and voices when presented with ADS. This ability emerged at 9 months of age when presented with IDS. Altogether, these findings support the idea that the perception of multisensory gender coherence is influenced by the nature of social interactions.In Study 2, we used a novel 4D technique to reconstruct the dynamic internal representations of the six basic expressions in a pure case of acquired prosopagnosia (i.e., a brain-damaged patient severely impaired in recognizing familiar faces). This was done in order to re-examine the debated issue of whether identity and expression are processed independently. Our results revealed that our patient used all facial features to represent basic expressions, contrasting sharply with her suboptimal use of facial information for identity recognition. These findings support the idea that different sets of representations underlie the processing of identity and expression. We then examined our patient's ability to recognize static and dynamic expressions using her internal representations as stimuli. Our results revealed that she was selectively impaired in recognizing many of the static expressions; whereas she displayed maximum accuracy in recognizing all the dynamic emotions with the exception of fear. The latter findings support recent evidence suggesting that separate cortical pathways, originating in early visual areas and not in the inferior occipital gyrus, are responsible for the processing of static and dynamic face information.Moving on from our second study, in Study 3, we investigated whether dynamic cues offer processing benefits for the recognition of facial expressions in other populations with immature or fragile face processing systems. To this aim, we conducted a large sample cross-sectional study with more than 400 participants aged between 5 to 96 years, investigating their ability to recognize the six basic expressions presented under different temporal conditions. Consistent with previous studies, our findings revealed the highest recognition performance for happiness, regardless of age and experimental condition, as well as marked confusions among expressions with perceptually similar facial signals (e.g., fear and surprise). By using Bayesian modelling, our results further enabled us to quantify, for each expression and condition individually, the steepness of increase and decrease in recognition performance, as well as the peak efficiency, the point at which observers' performance reaches its maximum before declining. Finally, our results offered new evidence for a dynamic advantage for facial expression recognition, stronger for some expressions than others and more important at specific points in development.Overall, the results highlighted in this thesis underlie the critical importance of research featuring dynamic stimuli in face perception and expression recognition studies; not only in the field of prosopagnosia, but also in other domains of developmental and clinical neuroscience.
