Distance and ratio effects in the flanker task are due to different mechanisms.

Full Abstract

When participants must respond to a relevant central target and ignore irrelevant flanking stimuli the flanking stimuli produce a compatibility effect, with increased response speed and accuracy on compatible as compared to incompatible trials. This flanker effect is larger when compatible trials are more frequent than incompatible trials (the ratio effect). A potential explanation of this ratio effect is that the occurrence of frequent incompatible trials causes the focus of spatial attention to be set narrower than when there are frequent compatible trials. The present investigation tests this hypothesis by comparing the flanker effect with near and far flankers. The hypothesis predicts that the flanker distance should modulate the ratio effect more when incompatible trials are frequent than when compatible trials are frequent. The results, however, show the opposite pattern:
Distance effects are larger in conditions with frequent compatible trials. Moreover, the effect of distance but not the ratio effect was eliminated when flanker distance remained fixed across blocks of trials, and also when participants had to attend to flanker stimuli in a go-no-go task. These results suggest that the ratio effect does not result from an adjustment of the focus of spatial attention.

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Author information

Author/s: Mattler, Uwe (U);

Affiliation: Department of Neurology II, Center for Advanced Imaging, Otto-von-Guericke Universität, Magdeburg, Germany. uwe.mattler(-atsign-)medizin.uni-magdeburg.de

Journal and publication information

Publication Type: Journal Article

Journal: Quarterly journal of experimental psychology (2006) (Q J Exp Psychol (Colchester)), published in England. (Language: eng)

Reference: 2006-Oct; vol 59 (issue 10) : pp 1745-63

Dates: Created 2006/09/01; Completed 2006/12/04;

PMID: 16945858, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Analysis of Variance
Attention - physiology
Discrimination Learning - physiology
Humans
Pattern Recognition, Visual - physiology
Psychomotor Performance - physiology

Psychomotor Performance - physiology
Reaction Time - physiology
Reproducibility of Results
Space Perception - physiology
Students - psychology
Task Performance and Analysis

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