Brief articleIs inhibition of return a reflexive effect?
Section snippets
IOR as a reflexive phenomenon
One line of evidence supporting the view that IOR is reflexive concerns the superior colliculus (SC), a primitive subcortical neural system. Posner, Rafal, Choate, and Vaughan (1985) were the first to suggest that IOR may be mediated by the SC. They found that patients suffering from degeneration of the midbrain, including the SC, do not produce an IOR effect, whereas comparable patients without midbrain damage do exhibit IOR (see also Danziger, Fendrich, & Rafal, 1997). More recently, IOR has
Is the IOR effect really a reflexive phenomenon?
While it is true that the cue does not predict where a target will appear, the cue is highly predictive as to when a target will appear. In other words, although there is no reason to attend to the cue based on its unreliable spatial information, there is good reason to attend to the cue because of its reliable temporal information (Milliken et al., 2003, Mondor, 1999; see also Kingstone, 1992, Snyder and Kingstone, 2001 for demonstrations that spatial attention is allocated to a signal to
Participants
Fifty participants (mean age 20.3 yrs; 32 females) at the University of British Columbia participated for course credit. Participants were assigned randomly to one of five groups (N=10): a baseline group that had a cue and target on every trial (BL), two control groups that had no cue either 5 or 25% of the time (NoC5, NoC25), and finally two experimental groups, which had no target after the cue either 5 or 25% of the time (NoT5, NoT25).
Apparatus and stimuli
The stimuli were white figures on a black background,
Results
Data from trials in which both a cue and a target occurred were examined. Mean correct RT as a function of cue validity and SOA are shown for each group in Fig. 1. Anticipations (<100 ms) and unusually slow responses (>1000 ms) were excluded, accounting for 2.1% of the data. As seen in Fig. 1, the most striking aspect of the data is the elimination of the foreperiod effect in the NoT25 group as evidenced by the lack of any decline in RT as a function of SOA (Fig. 1E). This effect indicates that
Discussion
The IOR effect is thought to reflect reflexive processing because it is normally observed in circumstances utilizing spatially irrelevant peripheral cues. While these cues are assumed to elicit reflexive attentional processes alone, they are typically used volitionally to prepare for when a target may appear. We tested whether the IOR effect depends on this volitional preparation. Eliminating preparation for target onset would indicate whether or not the IOR effect is a byproduct of using a
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