EPISODIC THEORY OF THE DYNAMICS OF SPATIAL ATTENTION

Previous measurements of visual attention in simple reaction time, cho ice reaction time and complex discrimination experiments in which atte ntion was purported to move continuously across space are reanalyzed. These data and data from attention gating experiments are quantitative ly predicted by an episodic (quantal) theory of spatial attention that proposes instead: (1) visual attention can be resolved into a sequenc e of discrete attentional acts (episodes), (2) each attentional episod e i is defined by its spatial attention function f(i)(x,y), (3) the sm ooth transition at time t(o) between episodes is described by a tempor al transition function G(t - t(o)), and (4) f and G are space-time sep arable. In new experiments, which use a concurrent motor reaction time task to control for nonattentional factors, the duration of an attent ion transition is shown to be independent of the distance traversed an d of the presence of interposed visual obstacles.