[Effect of stimulus opening size in global dominance with orientation classification task].

The aims of this study is to examine whether global dominance depends on the opening size of the stimulus with concentric hierarchical figures and orientation classification task and to determine the role of the salience of global opening and its coincidence with vertical symmetry axis of context. In the first experiment, participants had to indicate the opening direction of stimuli, which were open-left and open-right figures. Three openings were included: 10, 25 and 50% of the total circle perimeter. The results showed a local advantage with stimuli of 10%, absence of global or local advantage with stimuli of 25% and global advantage with stimuli of 50%. In the second experiment, stimuli with an opening of 50% were presented randomly in several positions in the visual field in order to avoid the coincidence of global opening with the vertical symmetry axis of context. The results showed an absence of global or local advantage. These findings indicate that global dominance with orientation classification task depends on stimulus characteristics such as opening size, and strategies used in visual recognition.