Localisation of "unseen" visual stimuli:: Blindsight in normal observers?

We developed two experiments on normal subjects to simulate "blindsight", i.e., above chance localization performance of visual stimuli without phenomenal awareness. In both experiments, visual targets were presented on a computer screen at one of six possible locations, followed by a metacontrast mask. Subjects (1) indicated whether they had seen the target stimulus or not, and (2) guessed at which location the stimulus had been presented. Fifty percent were blank trials. We found that even when Subjects did not acknowledge the presence of a stimulus, they nevertheless guessed its location with above chance accuracy. Apparent motion improved both detection and localization performance. Subjective confidence was related to stimulus presence and localisation performance. Thus, simulated blindsight appeared to be based on residual conscious awareness.