The time-course of pop-out search.

Olds, Cowan and Jolicoeur [2000. Tracking visual search over space and time. Psychonomic Bulletin & Review (in press)] interrupted pop-out search by adding distractors to a display after a delay. They analyzed the response time distributions from conditions with different delays for interruption and showed that when pop-out search fails, its partially completed computations can be used to assist other, slower search processes. This paper demonstrates that expectancies, numbers of items and colors in the display, and color onsets do not explain those results. Finally, an experiment in which the target was moved mid-trial demonstrates that partial pop-out assists difficult search by indicating something about where the target is, or where the target is not.