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Theses

Représentations visuelles précoces dans la catégorisation rapide de scènes naturelles chez l'homme et le singe.

Abstract : Humans and monkeys can process objects in natural scenes very rapidly and the three chapters of this
thesis try to define the different aspects of the early representations that underlie rapid visual
categorization.
In the first chapter, we show that magnocellular information is probably highly involved in the
construction of an early visual representation. The coarse description of the visual scene could be
helpful to guide the processing of the delayed parvocellular information.
The second chapter deals with the chronometry of visual processing by analyzing the results of
different types of tasks designed to minimize behavioral reaction times and the latency of differential
ERP activity. We also use a masking protocol in which a mask is presented shortly after the image to
decompose the precise dynamics of visual processing and this technique reveals the great importance
of the first 20-40 ms of information processing.
The third chapter explores the nature of early visual representations and the type of tasks we can
perform with them. Experiments in which subjects had to categorize animals at different levels show
that the first level accessed is not at the basic but rather at the superordinate level. This finding
contradicts previous results obtained with lexical experiments and strongly suggests that other
components such as the subject's expertise and the diagnosticity of visual features can explain the
processing speed when accessing to the different levels of categories.
These results allowed us to characterize the early representations that the visual system is using to
extract the meaning of a scene and construct through an emerging process the internal representation
of the world that is consciously perceived.
Document type :
Theses
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https://tel.archives-ouvertes.fr/tel-00077594
Contributor : Catherine Marlot Connect in order to contact the contributor
Submitted on : Wednesday, May 31, 2006 - 1:26:35 PM
Last modification on : Wednesday, October 20, 2021 - 12:45:40 AM
Long-term archiving on: : Monday, April 5, 2010 - 9:09:59 PM

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  • HAL Id : tel-00077594, version 1

Citation

Marc Macé. Représentations visuelles précoces dans la catégorisation rapide de scènes naturelles chez l'homme et le singe.. Neurosciences [q-bio.NC]. Université Paul Sabatier - Toulouse III, 2006. Français. ⟨tel-00077594⟩

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