Mapeamento espacial da atenção visual mobilizada pela via visual ventral

Abstract

Azevedo AMS. Mapping the spatial visual attention mobilized by the ventral visual pathway [Master Thesis (Human Physiology)]. Sao Paulo: Instituto de Ciencias Biomedicas, Universidade de Sao Paulo; 2009. The distribution of the attention in the visual field has been described in terms of diverse metaphors which have in common the anisotropy of such distribution. The visual information processing is taken in two different ways, the Dorsal pathway and the Ventral pathway. The first one selects information about object localization and movement (a.k.a. “Where?” pathway). It is mobilized, for example, by Simple Reaction Time tasks (SRT). The second one selects information about the object shape and/or color recognition (a.k.a. “What?” pathway) and is mobilized, for example, by Choice Reaction Time tasks (CRT). The present study presents an innovative approach to investigate the attentional resources distribution in large visual field areas. Opposing to the current psychophysical protocol with which few points are sampled many times in the visual field, it is opted to a more points and few time presented sampling protocol (80 to 150 points), in which a larger mapping of the visual field is obtained. Such consequence is a better detailment of the attentional visual resources generating a map of the attention distribution in the whole sampled visual field. Three experiments of voluntary attention mobilization were made: I. Task 1: SRT, mobilizing the Dorsal pathway. The experimental subjects were instructed to do not attend any particular region of the computer screen, characterizing a diffuse attention paradigm. II. Task 2: CRT, mobilizing the Ventral pathway. The experimental subjects were instructed to choose one in two possible answers depending on the presented stimuli in a trial. The possible stimuli were green or red and each color should be answered by triggering a button with a predetermined instruction (index and medium finger) once again in a diffuse paradigm. III. Task 3: CRT, with the experimental subject being instructed to focus attention in two frames with 10o eccentricity right and left of the screen, characterizing a splitted attention paradigm. The results showed anisotropy in the diffuse attention distribution, in favor of the lower hemifield for SRT and superior hemifield for CRT, in accordance to the evolutive concerns on the development of the visual pathways. In the splitted attention paradigm clear evidence of the presence of two attentional focuses were obtained, contributing to the hypothesis of the possibility of attention splitting when the Ventral pathway is mobilized.