The dynamics of saliency-driven and goal-driven visual selection as a function of eccentricity.

Both saliency and goal information are important factors in driving visual selection. Saliency-driven selection occurs primarily in early responses, whereas goal-driven selection happens predominantly in later responses. Here, we investigated how eccentricity affects the time courses of saliency-driven and goal-driven visual selection. In three experiments, we asked people to make a speeded eye movement toward a predefined target singleton which was simultaneously presented with a non-target singleton in a background of multiple homogeneously oriented other items. The target singleton could be either more or less salient than the non-target singleton. Both singletons were presented at one of three eccentricities (i.e., near, middle, or far). The results showed that, even though eccentricity had only little effect on overall selection performance, the underlying time courses of saliency-driven and goal-driven selection altered such that saliency effects became protracted and relevance effects became delayed for far eccentricity conditions. The protracted saliency effect was shown to be modulated by expectations as induced by the preceding trial. The results demonstrate the importance of incorporating both time and eccentricity as factors in models of visual selection.