Academic journal article Attention, Perception and Psychophysics

Oculomotor Inhibition of Return: How Soon Is It "Recoded" into Spatiotopic Coordinates?

Academic journal article Attention, Perception and Psychophysics

Oculomotor Inhibition of Return: How Soon Is It "Recoded" into Spatiotopic Coordinates?

Article excerpt

Published online: 26 May 2012

© Psychonomic Society, Inc. 2012

Abstract When, in relation to the execution of an eye movement, does the recoding of visual information from retinotopic to spatiotopic coordinates happen? Two laboratories seeking to answer this question using oculomotor inhibition of return (IOR) have generated different answers: Mathôt and Theeuwes (Psychological Science 21:1793-1798, 2010) found evidence for the initial coding of IOR to be retinotopic, while Pertzov, Zohary, and Avidan (Journal of Neuroscience 30:8882-8887, 2010) found evidence for spatiotopic IOR at even shorter postsaccadic intervals than were tested by Mathôt and Theeuwes (Psychological Science 21:1793-1798, 2010). To resolve this discrepancy, we conducted two experiments that combined the methods of the previous two studies while testing as early as possible. We found early spatiotopic IOR in both experiments, suggesting that visual events, including prior fixations, are typically coded into an abstract, allocentric representation of space either before or during eye movements. This type of coding enables IOR to encourage orienting toward novelty and, consequently, to perform the role of a foraging facilitator.

Keywords Spatial vision * Eye movements * Visual attention * Inhibition of return

Efficient sampling of the visual world, when achieved by changes in gaze direction, is determined by a multitude of factors. In visual search, for example, task demands (cf. Dodd, Van der Stigchel, & Hollingworth, 2009; Smith & Henderson, 2009), bottom-up factors that concern the natural salience of objects (see Wolfe & Horowitz, 2004, for a review), and importantly, a "memory" of previously sampled locations (cf. Peterson, Beck, & Vomela, 2007) are all at play. One mechanism proposed to afford this memory function is known as inhibition of return (IOR; Itti & Koch, 2001; Klein, 1988; Klein & Maclnnes, 1999; Posner & Cohen, 1984). IOR, in broad strokes, refers to the robust phenomenon of increased saccadic or manual response times to targets in previously inspected locations, relative to those in previously unattended, and distance-matched, locations.

IOR is traditionally explored in a cueing paradigm in which a peripheral onset target is preceded by an uninfor- mative peripheral cue. The peripheral cue is believed to automatically capture attention when, at short cue-target onset asynchronies (CTOAs), processing of targets is faster when they are presented at cued rather than at uncued locations (facilitation effect). At longer CTOAs, processing of targets at the cued location is hindered (IOR effect). Both mechanisms are ecologically important. The facilitation mechanism prioritizes the processing of salient events in the environment, while IOR encourages orienting toward novel locations (Posner & Cohen, 1984; Posner, Rafal, Choate, & Vaughan, 1985), and thus facilitates foraging behaviors (Klein, 1988; Klein & Maclnnes, 1999).

With each successive eye movement, objects within the visual field are represented in new retinal coordinates. To function effectively as a foraging facilitator (Klein & Dukewich, 2006), IOR must be coded in spatiotopic rather than merely in retinotopic coordinates. Note that in using the term "spatiotopic," we are referring to a nonretinotopic, environmental reference frame. This is exactly what Posner and Cohen (1984) found in their seminal report on IOR (see also Maylor & Hockey, 1985). However, the spatiotopic reference frame was put in question by Golomb, Chun, and Mazer (2008), who proposed that the "visual system's native or low-level representation of endogenously main- tained spatial attention is retinotopic, and remapping of attention to spatiotopic coordinates occius slowly and only when behaviorally necessary" (p. 10654). In response to this claim, two recent studies (Mathôt & Theeuwes, 2010; Pertzov, Zohary, & Avidan, 2010) have explored the time coiuse of the retinotopic and spatiotopic coding of IOR with a task similar to that used by Maylor and Hockey. …

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