LaPsyDÉ

Inhibition as a core mechanism for global/local visuo-attentional competition : developmental perspectives

Co-supervised by Nicolas Poirel & Olivier Houdé

Abstract
The visual world around us is extremely complex and has a great deal of information embedded in various sources that compete for our attentional resources. Our cognitive system must select a limited amount of visual information, which allows one to adapt to the environment. The perceptive saliency of a piece of information automatically biases attentional resources towards it, and this process is often useful and adaptive. Nevertheless, when the advantaged information is not the most pertinent available, additional mental effort is necessary to suppress it and to select the information of interest. The purpose of this thesis is to connect models of attentional selection and inhibition to the global precedence effect. The latter describes the faster processing of the global structure of an object compared to its local constitutive parts as well as the interference from global to local level. This global precedence effect seems to exist in preschoolers, but appears to be sensitive to manipulations of saliency: when the local elements are dense, the global form spontaneously emerges and is prioritized; however, when local elements are sparse, they seem to be processed with priority. The main goal of this thesis is to specify the global/local development by 1) studying the attentional competition between global, intermediate and local hierarchical levels during development and 2) highlighting the central role of inhibitory control when selecting the less salient level. With a visual search task, we demonstrated that in adults the local level is always disadvantaged during the attentional competition for resources compared to more structural, global and intermediate, levels. Although children showed a similar pattern of results, the selection of the local level was impaired in 5- and 6-year-old children who committed more errors than older children and adults. This result indicates there is a lack of inhibition of the global form in preschoolers. With a negative priming paradigm, we validated the idea that adults and 7-year-old children need to inhibit the global hierarchical level (the most salient one) to select the local hierarchical level (the less salient one). However, when using sparse hierarchical figures, this pattern of results was reversed in 7-year-old children but not in adults. A local inhibition, instead of a global inhibition, seems to be necessary in children when processing sparse figures. Regardless of which level is the most salient at each age, the inhibition process appears necessary to suppress the information at the salient and non-pertinent level in order to select the less salient but most relevant information. Taken together, and with regards to models of attentional selection and inhibition and to dynamic theories of development, these results provide new interpretations and perspectives in the study of the global precedence effect in children and adults.