This study involved two experiments. The goal of the first was to evaluate how visual attention is distributed spatially within an object, and how a spatial distribution may change over time. We accomplished this by having people press a button as soon as they noticed a target appear at various onset times and locations within an arch-shaped object. In the second experiment, we extended the arch-object and cued one end of it, in order to examine whether attention is biased to follow the shape of an object even if such a mechanism reduces the efficiency of a visual search. Results from the first experiment indicate that initially, there is no attentional bias to any location within an object. However, as looking time increases, a developing bias to the centre of objects occurs before attention adopts a strategic spatial distribution within the object. Results from the second experiment indicate that after attention is captured by a cued area, attention shifts away from the cued location. The path attention takes from the cued area is not constrained within the object. With increased time, however, attention does not move back to the cued location. Therefore, although attention is not constrained to follow the shape of the object one focuses on, it seems that the efficiency of a visual search is still jeopardized due to reluctance for attention to move to previously attended locations.
Symbolic control of visual attention: Semantic constraints on the spatial distribution of attention
