Abstract
Recent work in change blindness has shown that observers can detect changes in only a limited number of items at once (Rensink, 2000, Visual Cognition, 7, 345–376) and that homogeneity facilitates change detection (Rich & Gillam, 2000, Vision Research, 40, 1377–1384). Studies of visual search have also shown that homogeneity of distractors facilitates detection of static targets (Duncan & Humphreys, 1989, Psychological Review, 96, 433–458). The present study aimed to further examine the effects of homogeneity on detection of targets defined by change. We used a modified change detection task, in which a display consisting of an initial set of items was presented; then extra items were added to this display and then removed. The observer had to determine whether one of the initial, relevant items changed after the extra items were removed (in Experiment 1, on half the trials one of the initial items moved as the extra items disappeared; in Experiment 2, on half the trials one of the initial items disappeared when the extra items disappeared). The initial items were either homogeneous (all the initial items were the same colour) or heterogeneous (two colours of initial items). It was expected that homogeneity would facilitate detection of changes in the initial set of items, at relevant set-sizes larger than 5, but this was not the case. These results are discussed in relation to the literature and to the attentional mechanisms responsible for detecting change.