Abstract
Perhaps the most striking phenomenon of visual awareness is inattentional blindness (IB), in which a surprisingly salient event right in front of you may go completely unseen when unattended. Does IB reflect a failure of online perception, or only of subsequent encoding into memory — a form of "inattentional amnesia" (e.g. Wolfe, 1999)? Previous work has been unable to answer this question, due to a seemingly intractable dilemma: ruling out memory requires immediate perceptual reports, but soliciting such reports fuels an expectation that eliminates IB. Here we introduce a way to escape this dilemma, reporting two experiments that evoke repeated IB in the same observers, in the same session, and even when unexpected events must be immediately reported, mid-event. We employed a sustained IB task: after several trials of a demanding primary tracking task, an Unexpected Event (UE) occurred: a new object (with a novel shape, color, and motion direction compared to everything else in the display) appeared, after which observers were asked (in various ways) whether they had noticed it. Subsequently, observers had to immediately press a key any time (throughout the rest of the experiment) they saw something different or unexpected. Observers made use of such keypresses when the very same UE was later repeated, but when an equivalent UE with entirely new features (now differing in color, shape, and motion direction from all of the other objects and from the previous UE) subsequently appeared, observers failed to report it — even mid-event, during the 5 seconds that it traversed the display. Thus, observers fail to see salient events not only when they have no expectation, but also when they have the wrong expectations. These experiments demonstrate that IB is aptly named: it reflects a genuine deficit in moment-by-moment conscious perception, rather than a form of inattentional amnesia.
Meeting abstract presented at VSS 2015