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Volume 3, Pages 75-86
Research Article

Inhibition of Return Biases Orienting During the Search of Complex Scenes

Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, Canada

Academic Editor: Michael Posner

Copyright © 2003 W. Joseph Macinnes and Raymond M. Klein.


In Klein and MacInnes[1], observers searched a complex scene for a camouflaged target. Reflecting Inhibition of Return (IOR) observers were slower to detect and saccade to uncamouflaged probes that interrupted active search when these were placed in the vicinity of a recent fixation. To explore the generality of this finding of IOR during search, we changed the mental state of the observer at the time of the probes by instructing observers to inspect the scene until they found something interesting and stop there. After this voluntary cessation of search, we presented an uncamouflaged probe that observers were required to foveate. Extending our previous demonstration, we observed a relative increase in the time required to locate these probes when they were in the general region of a previous fixation so long as the scene was maintained. When the scene was removed, probe reaction time was unaffected by distance from the last fixation. The pattern of results supports the proposal that IOR biases overt orienting during search.