Prioritizing selection of new elements: on the time-course of the preview effect.

The preview effect demonstrates that if observers in a visual search task are allowed a preview of a subset of elements before another subset of new elements is added, the first subset of elements does no longer compete for attentional selection. The aim of the present study was to investigate how long after the presentation of the new elements the preview effect can be preserved. Observers were presented with displays containing one set of elements (old elements) followed after a certain time interval by a second set of elements (new elements). Observers searched for the presence of a target among the new elements. The target appeared through an equiluminant colour change at varying intervals after the presentation of the new elements. The results indicated that the preview effect disappears beyond 200 ms after the presentation of the new elements. The results are discussed in terms of visual marking, temporal segregation, and onset capture. © 2005 Psychology Press Ltd.