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Flanker effects in peripheral contrast discrimination — psychophysics and modeling

Zenger-Landolt, Barbara and Koch, Christof (2001) Flanker effects in peripheral contrast discrimination — psychophysics and modeling. Vision Research, 41 (27). pp. 3663-3675. ISSN 0042-6989. doi:10.1016/S0042-6989(01)00175-4.

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We studied lateral interactions in the periphery by measuring how contrast discrimination of a peripheral Gabor patch is affected by flankers. In the psychophysical experiments, two Gabor targets appeared simultaneously to the left and right of fixation (4° eccentricity). Observers reported which contrast was higher (spatial 2-alternative-forced-choice). In different conditions, Gabor flankers of different orientation, phase, and contrast were present above and below the two targets, at a distance of three times the spatial Gabor period. The data show that collinear flanks impair discrimination performance for low pedestal contrasts but have no effect for high pedestal contrasts. The transition between these two result patterns occurs typically at a pedestal contrast which is similar to the flanker contrast. For orthogonal flanks, we find facilitation at low pedestal contrasts, and suppression at intermediate contrasts. We account for this complex interaction pattern by a model that assumes that flankers can provide additive input to the target unit, and that they further contribute to the target's gain control, but only in a limited range of pedestal contrasts; once the target contrast exceeds a critical value, inhibition becomes subtractive rather than divisive. We further make specific propositions on how this model could be implemented at the neuronal level and show that a simple integrate and fire unit that receives time-modulated inhibition behaves in a fashion strikingly similar to the model inferred from the psychophysical data.

Item Type:Article
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URLURL TypeDescription
Koch, Christof0000-0001-6482-8067
Additional Information:Received 7 November 2000; received in revised form 30 March 2001. © 2001 Elsevier Science Ltd. We would like to thank Jochen Braun, Gary Holt and Laurent Itti for helpful comments, and Christopher Tyler for stimulating comments at a ARVO poster presentation of this work. The research was supported by NSF, the NSF-sponsored “Neuromorphic Systems Engineering” Center at Caltech, NIMH and a Caltech Divisional Scholarship to BZ.
Group:Koch Laboratory (KLAB)
Funding AgencyGrant Number
NSF-sponsored “Neuromorphic Systems Engineering” Center at CaltechUNSPECIFIED
Subject Keywords:Lateral inhibition; Gain control; Attention; Contrast discrimination; Contrast detection; Masking; Subtractive inhibition; Divisive inhibition
Issue or Number:27
Record Number:CaltechAUTHORS:20130816-103240441
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Official Citation:Barbara Zenger-Landolt, Christof Koch, Flanker effects in peripheral contrast discrimination—psychophysics and modeling, Vision Research, Volume 41, Issue 27, December 2001, Pages 3663-3675, ISSN 0042-6989, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:40553
Deposited By: KLAB Import
Deposited On:11 Jan 2008 22:51
Last Modified:09 Nov 2021 23:49

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