Academic journal article Canadian Journal of Experimental Psychology

The Role of the Fixation Location in Inhibition of Return

Academic journal article Canadian Journal of Experimental Psychology

The Role of the Fixation Location in Inhibition of Return

Article excerpt

Abstract Experiments that have examined inhibition of return (IOR) have typically used trial sequences in which attention is reoriented to a central fixation location between the presentation of the peripheral cues) and the target. In examining the role of the fixation location in IoR, three experiments were conducted in which an exogenous cue was used to reorient attention following a peripheral cue and before the appearance of a target. However, this cue occurred at either the traditional central fixation location or a nonfixated location. The results indicate that reorienting attention to a fixated location results in a significant reduction in the inhibitory effect. The results from the study suggest that IOR could serve as a mechanism that improves the efficiency of visual searches.

The term inhibition of return (IOR) is used to refer to the finding that response latencies to targets are typically longer when the targets are presented at locations that had been previously stimulated. The typical finding is that following a peripheral cue, there is a brief period of facilitated target detection followed by a much longer period of inhibited target detection (IOR). Since the initial examination of the effect by Posner and Cohen (1984), IOR has provoked a considerable amount of research interest and, not surprisingly, this interest has yielded some consistent patterns of results and some conflicting patterns of results. One consistent pattern of results is that a keypress reaction time (RT) to detect a single target will be increased if the target is preceded by a single, uninformative, peripheral (exogenous) cue at that same location (e.g., Posner & Cohen, 1984). More controversy, however, surrounds issues concerning whether or not IOR occurs in discrimination tasks as well as detection tasks (e.g., Pratt, 1995; Terry, Valdez, & Neill, 1994), whether the inhibitory effect is both object-based and location-based (e.g., Miiller & Muhlenen, 1996; Tipper, Weaver, Jerreat, & Burak, 1994), whether the inhibition decays with practice (e.g., Pratt & McAuliffe, 1999; Weaver et al., 1998), and how many locations may be inhibited (e.g., Danzinger, Snyder, & Kingstone, 1998; Pratt & Abrams, 1995). Indeed, the very nature of the inhibition remains the focus of debate, and various attentional (e.g., Posner & Cohen, 1984; Pratt, Spalek, & Bradshaw, 1999), motoric (e.g., Klein & Taylor, 1994; Rafal, Calabresi, Brennan, & Sciolto, 1989; Taylor & Klein, 1998), and perceptual (e.g., Wright & Richard, 1996) explanations have been proposed.

Despite the breadth of the research that has been conducted on IOR, the experimental designs in the vast majority of these studies are variations of the basic cueing paradigm used by Posner and Cohen (1984). This straightforward design involved three horizontally aligned boxes, with the participant remaining fixated on the middle box. Then an exogenous cue was presented in one of the peripheral boxes, followed by a relatively long delay (at least 300 ms after the onset of the cue), and finally the target in one of the peripheral boxes. The notion put forward by Posner and Cohen was that attention was first drawn to the cued box, then reoriented back to fixation during the delay interval, and this resulted in the activation of a mechanism that biased attention from returning to previously attended locations. In subsequent experiments, Posner and Cohen added an exogenous cue at the fixation location during the delay interval (i.e., between the presentation of the peripheral cue and target) to ensure that attention was reoriented from the location of the exogenous cue to the fixation location.

Although the experimental designs that researchers have developed to examine IOR have (with some exceptions) often involved displays that are much more complicated than three boxes, the basic elements are the same. These elements are, in sequence: (a) fixate at a central location, (b) cue peripheral location(s), (c) have a long delay interval and/or cue the central fixation location, and (d) present the peripheral target. …

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