Please use this identifier to cite or link to this item:
Appears in Collections:Psychology Journal Articles
Peer Review Status: Refereed
Title: Spatial properties of curvature-encoding mechanisms revealed through the shape-frequency and shape-amplitude after-effects
Authors: Gheorghiu, Elena
Kingdom, Frederick A A
Contact Email:
Keywords: Contour-shape
Issue Date: Apr-2008
Publisher: Elsevier
Citation: Gheorghiu E & Kingdom FAA (2008) Spatial properties of curvature-encoding mechanisms revealed through the shape-frequency and shape-amplitude after-effects, Vision Research, 48 (9), pp. 1107-1124.
Abstract: The shape-frequency and shape-amplitude after-effects, or SFAE and SAAE, are phenomena in which adaptation to a sinusoidal-shaped contour results in a shift in, respectively, the perceived shape-frequency and perceived shape-amplitude of a test contour in a direction away from that of the adapting stimulus. Recent evidence shows that the SFAE and SAAE are mediated by mechanisms sensitive to curvature [Gheorghiu, E., & Kingdom, F. A. A. (2007a). The spatial feature underlying the shape-frequency and shape-amplitude after-effects. Vision Research, 47(6), 834-844]. Therefore we have used the SFAE and SAAE as a tool to study curvature processing. We examined whether curvature-encoding mechanisms are selective for (i) shape-phase, (ii) curvature polarity (or sign) and (iii) local orientation. We also investigated whether (iv) the two orthogonal dimensions of a curve, the sag and the cord, are encoded independently, and (v) whether curvature encoders are organized in an opponent manner. SFAEs/SAAEs were measured for adapting and test contours that differed or not in a given spatial property, the rationale being that if the after-effects were smaller when adaptor and test differed in a particular spatial property then curvature-encoding mechanisms must be selective for that spatial property. Our results reveal that SFAEs and SAAEs show (i) a degree of selectivity to curves that are mirror symmetric (in our stimuli half-cycle sine-wave contours in cosine (0/180deg) shape-phase); (ii) a degree of selectivity to the sign or polarity of curvature; (iii) a degree of selectivity to local orientation; (iv) independent coding of the sag and the cord of the curve, and (v) no evidence for opponent-curvature coding. The results agree with neurophysiological studies showing that simple shape dimensions are encoded independently.
Type: Journal Article
DOI Link:
Rights: The publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.
Affiliation: Psychology
McGill University

Files in This Item:
File Description SizeFormat 
Gheorghiu and kingdom (2008).pdf475.85 kBAdobe PDFUnder Embargo until 31/12/2999     Request a copy

Note: If any of the files in this item are currently embargoed, you can request a copy directly from the author by clicking the padlock icon above. However, this facility is dependant on the depositor still being contactable at their original email address.

This item is protected by original copyright

Items in the Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

If you believe that any material held in STORRE infringes copyright, please contact providing details and we will remove the Work from public display in STORRE and investigate your claim.