Academic journal article Attention, Perception and Psychophysics

The Mutations Paradigm: Assessing the Time Course of Distractor Processing

Academic journal article Attention, Perception and Psychophysics

The Mutations Paradigm: Assessing the Time Course of Distractor Processing

Article excerpt

Published online: 18 June 2015

© The Psychonomic Society, Inc. 2015

Abstract The temporal loci of distractor processing were assessed in a flanker task with mutating distractors. We introduce the mutations paradigm, which allows for behavioral assessments of the critical time window during which distractors are processed. A central target was flanked by two identical distractors. While the target remained unchanged throughout the trial, the distractors' identities mutated once per trial, at a random time during the initial 200 ms following onset. There were three types of trials: incongruent (i.e., disruptive) distractors that mutated to neutral distractors, neutral distractors that mutated to incongruent ones, or neutral distractors that mutated to different neutral distractors (control). The results revealed that presentations of incongruent distractors for a mere 17 ms were sufficient to significantly delay responses. After 50 ms, perceptual information ceased to be accumulated from distractors locations but was still being collected from the target location. We suggest that (a) extensive information about the target and distractors was gathered as early as 17 ms after onset; (b) attentional modulations of processing consummated later, between 34 and 51 ms; and (c) once attentional mechanisms had stepped in (~50 ms), selection achieved full and sustained efficiency. These findings seem to challenge basic assumptions held by early-selection, late-selection, and load theories.

Keywords Selective attention . Visual attention . Visual perception

Research on attention has mostly focused on the conditions under which the perceptual system fails to filter out irrelevant stimuli during the course of processing targeted stimuli (e.g., Stroop effects: MacLeod, 1991; Stroop, 1935; flanker effects: Eriksen, 1995; Eriksen & Eriksen, 1974;Miller,1991;global precedence effects: Kimchi, 1992; Navon, 1977; or Simon effects: Simon, 1990). We suggest that in order to explain undesired processing of task-irrelevant distractors, theoretical models have relied on specific assumptions regarding the temporal window during which distractors are processed. Inescapably, the adoption of different assumptions about the time course of attentional modulations of processing has led to fundamentally disparate interpretations of how attention operates. The main focus of the present study was to provide behavioral assessments of the critical time window during which information about distractors is accumulated.

Explicit and hidden assumptions about the temporal locus during which disruptive information about distractors infiltrates attentional selection have directly derived from theoretical propositions regarding the temporal locus of attentional operation. For instance, late-selection theories have suggested that initial perceptual processing is unrestricted and that targets are discerned from nontargets during later, postperceptual stages (Deutsch & Deutsch, 1963;Duncan,1980;Schneider &Shiffrin,1977). Thus, according to this view, information about distractors is continually accumulated for as long as the distractors are presented.

Early-selection theories, on the other hand, propose that initial processing proceeds automatically and in parallel, but can only retrieve coarse information. When necessary, resolution is improved by the activation of attentional mechanisms that filter the very inflow of perceptual information (Broadbent, 1958, 1970, 1971, 1981, 1982; Johnston & Dark, 1982; Lachter, Forster, & Ruthruff, 2004). Alternatively, perceptual-load theory (Lavie, 1995, 2005, 2010; Lavie & Tsal, 1994) proposes that if target selection demands less than all available resources (low load), then unused surplus resources end up processing neighboring nontargets. If so, distractor processing can only begin after targets have been selected.

Numerous studies have manipulated and assessed temporal variables in selection tasks. …

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