Abstract
The most common conceptualization of inhibition of return (IOR) is the robust finding of increased response times for saccadic or manual response times to targets that appear at previously cued locations following a cue-target interval exceeding ∼300 ms in the classic Posner cueing paradigm. Investigative work has explored variants on this cue-target paradigm to determine the extent to which IOR might comprise one or several largely orthogonal components. In a variation on this paradigm, Abrams and Dobkin (1994) presented a directional arrow at fixation as the imperative stimulus for a saccadic response to a placeholder that had previously been cued or uncued. In separate blocks the standard peripheral target was used. The key finding was that the magnitude of IOR was greater when a saccadic response was made to a peripheral than to a central arrow. It was concluded that saccadic responses to peripheral targets comprise motoric and perceptual components (the two components theory for IOR) whereas saccadic responses to a central target comprise a single motoric component. In contrast to the foregoing findings, Taylor and Klein (2000) discovered that IOR was equivalent for central and peripheral targets when these were randomly intermixed suggesting a single, motoric, flavor under these conditions. To resolve the apparent discrepancy, a strict replication of Abrams and Dobkin was conducted central and peripheral targets were either blocked or mixed. In the blocked design, peripheral targets resulted in more IOR than central targets, while in the mixed design, target type had no bearing on the magnitude of IOR. The blocked design creates untoward spatial expectancies for the target that can differentially affect the extent to which non-informative peripheral cues are processed; in other words, the blocked design allows two different attentional control settings, a confound that “masqueraded” as two components of IOR.
NSERC - Discovery Grant to Ray Klein.