Inhibition of Return: a bottom-up routed attentional process

Subjects are faster at detecting a visual target when its position is cued before onset (benefit) then when they are misinformed about its location (cost). A reversal of this cost-benefit pattern is observed when the cue-target interval (CTI) exceeds approximately 250ms (Inhibition of Return, IOR). In general, the reversal is found after exogenous and not after endogenous cueing. We demonstrate endogenous orienting that is (partially) based on bottom-up visual orienting processes to test the hypothesis that IOR is usually not observed in endogenous attention because no bottom-up attention processes are claimed. Therefore, we developed an endogenous split-cueing-task, in which a central colour cue is presented first, shortly before a second peripheral location cue. The location cue consists of the sudden onset of coloured squares left and right from fixation, with one square having the colour of the central cue... The colour of the central cue instructs to which peripheral location (colour) subjects need to orient. Such endogenous cueing possibly can trigger a bottom-up visual search of the matching peripheral colour. In a control condition, central and peripheral cues were presented simultaneously to prevent this bottom-up routed search. An IOR effect was observed in the endogenous split-cue condition, while no IOR was found in the control condition. These results suggest that IOR is associated with bottom-up guided endogenous orientation. It further demonstrates the need to no longer treat endogenous and exogenous processes on the one hand, and respectively, top-down and bottom-up processes on the other hand, as synonyms.