Elsevier

Acta Psychologica

Volume 185, April 2018, Pages 125-135
Acta Psychologica

Perceptual load is not always a crucial determinant of early versus late selection

https://doi.org/10.1016/j.actpsy.2018.02.004Get rights and content

Highlights

  • Does perceptual load determine whether selection occurs early or late?

  • In line with this view, a congruency effect appears in low- but not high-load trials.

  • Our study, however, reports a congruency sequence effect in high-load trials.

  • Thus, distractors are identified even when there is no congruency effect.

  • Perceptual load does not always determine the locus of selection.

Abstract

The perceptual load hypothesis posits that early and late selection occurs under conditions of high and low perceptual load, respectively. Recent work, however, suggests that the absence of a congruency effect in high-load trials – the behavioral signature of early selection in studies of perceptual load – may not provide an exhaustive index of failing to identify task-irrelevant distractors. Prior research also suggests that the congruency sequence effect (CSE) – a modulation of the congruency effect after incongruent relative to congruent trials – provides complementary information about whether participants identify distractors. We therefore conducted a novel test of the perceptual load hypothesis that employed both the congruency effect and the CSE as measures of distractor identification. Experiment 1 revealed that distractors were identified not only in low-load trials but also in high-load trials wherein there was no overall congruency effect. Experiment 2 further revealed which task parameters allowed us to observe such “hidden" distractor identification. These findings suggest that perceptual load is not always a crucial determinant of early versus late selection.

Section snippets

A proposed resolution to the early-versus-late selection controversy

Lavie and colleagues (Lavie, 1995; Lavie & Tsal, 1994) have proposed that perceptual load is a crucial determinant of whether selection in the visual modality occurs early or late. Perceptual load refers to the demands that identifying task-relevant visual stimuli impose on perceptual attention. When identifying such stimuli is relatively easy (i.e., when perceptual load is low), the perceptual load hypothesis posits there are sufficient perceptual resources remaining to identify task-irrelevant

Is the overall congruency effect an exhaustive measure of whether participants identify a distractor?

Contrary to the assumptions of the perceptual load hypothesis, Cosman and colleagues (Cosman, Mordkoff, & Vecera, 2016) recently suggested that the congruency effect is not an exhaustive measure of whether distractors are identified. They suggested that the congruency effect depends not only on identifying the distractor but also on post-identification processes that map the distractor onto an arbitrary response. In this view, a failure of stimulus-response (S-R) translation for the distractor,

The present study

Given the limitations of Cosman et al.'s (2016) study, we revisited the issue of whether perceptual load influences whether selection occurs early or late in the standard flanker task. Moreover, we employed a complementary measure of distractor processing – the congruency sequence effect (CSE) – to provide a novel test of the perceptual load hypothesis. The CSE is a phenomenon wherein the congruency effect differs after incongruent relative to congruent trials (Gratton, Coles, & Donchin, 1992).

Experiment 1

In Experiment 1, we investigated whether a CSE is present under conditions of high perceptual load even when there is no overall congruency effect. To this end, we employed Cosman et al.’s (2016) standard flanker task (see also, Lavie, 1995). As described earlier, the perceptual load hypothesis posits that participants fail to identify distractors under conditions of high perceptual load and, therefore, predicts no CSE will be observed (Lavie, 1995). In contrast, other views predict a typical

Experiment 2

The goal of Experiment 2 was to investigate whether presenting the non-target items in high-load search arrays in the same relative positions across trials reduces or eliminates the reverse CSE we observed in Experiment 1. This manipulation should reduce demands on visual search and thereby reduce the degree to which increasing perceptual load increases overall task difficulty. It should also reduce the degree to which salient contextual features of the display change in consecutive trials. We

General discussion

The present study revealed an important, novel result. In particular, it revealed evidence that distractors are identified in high-load trials even when there is no overall congruency effect. As described next, this finding has important implications for the literature on selective attention.

Conclusion

Our findings suggest that perceptual load is not always a crucial determinant of whether selection occurs early or late. Specifically, they provide evidence that participants identify irrelevant distractors in the standard flanker task not only when perceptual load is low, but also when perceptual load is high and there is no overall congruency effect. Future work investigating whether our findings generalize to other tasks may shed additional light on the conditions under which perceptual load

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  • Cited by (0)

    The authors thank Toby Mordkoff and Tessa Abagis for helpful feedback on a draft of this manuscript, and Lauren Grant and Sandra Oska for assisting with data collection.

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