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Previewing distracters reduces their effective contrast

Allen, Harriet A.; Humphreys, Glyn W.

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Professor of Lifespan Psychology

Glyn W. Humphreys


In a visual search task, when half the distracters are presented earlier than the remainder (‘previewed’), observers find the target item more efficiently than when all the items are presented together—the preview benefit. We measured psychometric functions for contrast increments on Gabors that were presented as a valid preview for subsequent search, and when they were a non-predictive (dummy) preview. Sensitivity to contrast increments was lower (rightwards shift of the psychometric function) on valid, compared to dummy previews. This is consistent with an account of the preview benefit in terms of active inhibition, equivalent to lowering the contrast of previewed items that are being actively ignored.


Allen, H. A., & Humphreys, G. W. (2007). Previewing distracters reduces their effective contrast. Vision Research, 47(23),

Journal Article Type Article
Publication Date Oct 1, 2007
Deposit Date Mar 15, 2016
Publicly Available Date Mar 15, 2016
Journal Vision Research
Print ISSN 0042-6989
Electronic ISSN 1878-5646
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 47
Issue 23
Keywords Attention, Contrast Sensitivity, Inhibition, Marking, Visual Search
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