Searching for Feature-Based Surround Suppression in Inattentional Blindness
33.4009, Sunday, 17-May, 8:30 am - 12:30 pm, Pavilion
Trafton Drew1; 1Department of Psychology, University of Utah
When engaged in an attention-demanding task, Observers (Os) often miss stimuli that would otherwise be perfectly obvious, like a dancing gorilla or a clown on a unicycle, a finding known as Inattentional Blindness (IB). Previous work has shown noticing rates for unexpected stimuli increase as the similarity to the target increases: when tracking white items, Os are much more likely to notice an unexpected white stimulus than a black one. Most and colleagues (2001), showed that noticing rates follow a simple linear relation with the similarity of the attended stimulus, even for unexpected items of novel color (e.g. a grey item when tracking white items and ignoring black items). We wondered whether the presence of distractors in these intermediate positions would change the pattern of results. The presence of the distractors that share a similar color to the attended objects may result in this color being inhibited in feature space. Recent behavioral and electrophysiological work has suggested that feature-based suppression operates on colors that are similar (~30° in hue space) to the attended color (Störmer et al., 2014). For example, visual search performance for two colors separated by 30° in hue space was worse than performance for two colors separated by 75°. Os in the current study attended objects colored X while ignoring an equal number of distractors colored X+30° and X+180°. We measured IB rates for unexpected items of attended, near-attended and far from attended colors in different Os. Inconsistent with the predictions of surround suppression, IB rates were inversely proportional to similarity to the attended color. The results suggest that while we may use feature-based suppression to inhibit near-target colors under some circumstances, this does not manifest itself in reduced noticing rates during Inattentional Blindness.