Surprise capture and inattentional blindness.

Inattentional blindness (IB) is the phenomenon where unattended objects are not noticed. IB is typically tested within a surprise presentation procedure: A novel object is presented on a critical trial for the first time without prior announcement. Previous research indicates that IB is high unless the novel object is (a) similar to the target of the present task or (b) perceptually salient. The present study seeks evidence that the expectancy congruence of the novel object is a further important determinant of IB, and that the novel object is frequently noticed if it has a feature that is expectancy discrepant. An influence of perceptual saliency is excluded by presenting only two objects in each display. Experiment 1 reveals that an expectancy discrepant novel feature is noticed even if it is completely dissimilar to the target. Experiment 2 shows that expectancy discrepancy and match to target features can prioritize an object at the same time. Experiment 3 shows that IB is related to the degree of expectancy discrepancy. Results indicate that IB is prevented by two factors: match to target set and expectancy discrepancy. A revised model for IB is suggested.