Abstract
We explored whether the phenomenon of Negative Choice (Allakverdov, 2009), a tendency to be unaware of a stimulus you were previously unaware of, occurs for the critical stimulus not seen due to inattentional blindness (IB) (Mack & Rock, 1998). Using a sustained IB procedure, (Simons & Chabris, 1999), observers watched the ball tossing video and counted the number of passes of balls during which an umbrella-carrying woman, (the critical stimulus), walks through the scene. Following the video, subjects had to identify each of 12 grayscale images of people with accessories (e.g. a man with a suitcase), including an image of the “umbrella-woman” (the IB target). In order to make identification more or less difficult, each of the images was overlaid with a snapshot of the video scene that did not contain the critical stimulus. These overlays created different levels of opacity ranging from 20% to 90%, thus varying the visibility of the target image while preserving the context of the video and making the identification task more or less demanding. 126 observers were tested and nearly 60% demonstrated IB. The dependent measure was the percentage of correct identifications of target images associated with degree of opacity. The results revealed that IB observers were only able to identify the target image to which they had previously been blind when the image was 30% percent more visible than it was to control subjects who had not participated in the IB experiment (p < 0.01). There was no difference in the level of identification of non-target images between IB subjects, non-IB subjects, and control subjects who did not watch the video. We interpret the data obtained to be a demonstration of Negative Choice of a stimulus previously unseen during a sustained Inattentional Blindness procedure.