Abstract
Previous experiments have shown that people miss a visible but unexpected object in a field of other objects when engaged in an attentionally demanding task. Yet no previous experiment has examined the extreme case of blindness to a single object appearing alone in the visual field. In two experiments we evaluated whether a perceiver’s prior expectations could alone obliterate his or her awareness of a salient visual stimulus. To establish expectancy, observers first made a demanding visual discrimination on each of three baseline trials. Then, on a fourth, critical trial, a single, salient and highly visible object appeared in full view at the center of the visual field and in the absence of any competing visual input or competing task demands. Surprisingly, fully half of the participants were unaware of the solitary object in front of their eyes. Yet in a control condition these same observers easily detected the same object in the same screen position. Dramatically, observers were even blind when the only stimulus on display was the face of U.S. President Barack Obama. We term this novel, counterintuitive phenomenon, Barack Obama Blindness (BOB). Employing a method that rules out putative memory effects by probing awareness immediately after presentation of the critical stimulus, we demonstrate that the BOB effect is a true failure of conscious vision.
Meeting abstract presented at VSS 2015