Cite as:
Solomon J A, Morgan M J, 2003, "Flanked targets: easier to see, harder to identify" Perception 32 ECVP Abstract Supplement

Flanked targets: easier to see, harder to identify

J A Solomon, M J Morgan

Crowding refers to the difficult identification of peripherally viewed targets amidst similar stimuli. Flanking facilitation refers to the easy detection of an oriented target when it appears amidst collinear stimuli in the centre of the visual field. These two well-documented effects seem difficult to reconcile within any unified framework for visual detection and identification. To quantify these effects, we measured the accuracy with which observers could discriminate between clockwise and anticlockwise tilts and the contrast required for detection of nearly horizontal targets in the presence and absence of horizontal flanks and spatially coincident pedestals. The effect of flanks upon identification accuracy was much greater than the effect of a pedestal that similarly lowered detection threshold. It was even greater than would be predicted if estimates of target and flank orientations were averaged prior to identification. A single population of orientationally selective filters can simultaneously produce identification accuracies and detection thresholds similar to those we measured with and without spatially coincident pedestals, but not those we measured using spatially separate flanks. Previously, we have proposed a filter - rectify - filter model of flanking facilitation. A population of these second-order filters can simultaneously produce thresholds similar to those we measured using flanks.

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