Dissecting Spatial Visual Attention

it has been recognized that at least two forms of spatial attention can be found in vision. For example, Wundt (1902) observed that attention could be involuntary or voluntary. A variety of distinctions have been made that more or less correspond to Wundt’s distinction, including goal-directed attention versus stimulus-driven capture and endogenous attention versus exogenous attention. the terms used to label these forms of attention are not important. the critical question is whether these two forms of attention involve the same or different mechanisms, and, if they involve different mechanisms, what are those mechanisms? modern investigators have largely been unclear whether voluntary and involuntary forms of attention are mediated by different mechanisms or whether they are simply different means of controlling a single mechanism. rather, most contemporary investigations have focused on the properties of different methods of summoning attention. the assumption is often made that involuntary attention has the same effect on perceptual processes as voluntary attention (rauschenberger, 2003) and that they affect the same neural mechanisms (Gazzaniga, ivry, & mangun, 1998). the research reported here challenges this assumption. three separate behavioral paradigms demonstrate that voluntary and involuntary forms of attention