Abstract
Purpose: In these experiments we investigated the role of object shape and size in attentional capture by presenting an irrelevant object in the visual field and measuring performance on a visual search task. Methods: The stimuli of the search task were presented around the fixation point, inside a frame. This frame was an outlined geometric shape, not informative to the search task. An exogenous cue that could be valid, invalid or neutral, informed the participant about the frame inside which the stimuli would be presented. The cue and frames were circles and squares of different sizes (Exp. 1) or a square and, a vertical or horizontal rectangle (Exp 2 and 3). In Exp 3 a flanker stimuli, compatible or incompatible with the visual search target, was presented inside or outside the frame area (a vertical or horizontal rectangle). The participants were instructed to ignore the geometric shapes and focus on the search task. Results: In spite of not being informative to the search task, cueing the geometrical shape produces a gain in the search performance. Cueing the size of the shape is more efficient than cueing just its shape. Cueing the orientation of a rectangle is effective and dependent on its specific orientations. The flanker effect is dependent on the frame orientation, flanker compatibility and flanker position inside or outside the frame. Conclusions: Despite the instructions the participants were not able to ignore the irrelevant object. The effectiveness of object cueing is evidence that object shape and size can capture attention reflexively.
CNPq, Fapesp (CG), NSERC, FCAR (MvG)