Sensitivity to visual features in inattentional blindness.

The relation between attention, perception, and awareness is among the most fundamental problems in the science of the mind. One of the most striking and well-known phenomena bearing on this question is (IB). In IB, naive observers fail to report clearly visible stimuli when their attention is otherwise engaged-famously missing a gorilla parading before their eyes. IB carries tremendous significance, both as evidence that awareness requires attention and as a tool in seeking the neural correlates of consciousness. However, such implications rest on a notoriously biased measure: asking participants whether they noticed anything unusual (and interpreting negative answers as reflecting a complete lack of perception). Here, in the largest ever set of IB studies, we show that, as a group, inattentionally blind participants can successfully report the location, color, and shape of stimuli they deny noticing, demonstrating that perceptual information remains accessible in IB. By introducing absent trials, we further show that observers are collectively biased to report not noticing in IB-essentially 'playing it safe' in reporting their sensitivity. These data provide the strongest evidence to date of significant residual visual sensitivity in IB. They also challenge the use of inattentional blindness to argue that awareness requires attention.