Binocular contrast interactions: dichoptic masking is not a single process

Baker, Daniel H. and Meese, Tim S. (2007) Binocular contrast interactions: dichoptic masking is not a single process. Vision Research, 47, (24), 3096-3107. (doi:10.1016/j.visres.2007.08.013).


[img] PDF - Version of Record
Download (501Kb)


To decouple interocular suppression and binocular summation we varied the relative phase of mask and target in a 2IFC contrast-masking paradigm. In Experiment I, dichoptic mask gratings had the same orientation and spatial frequency as the target. For in-phase masking, suppression was strong (a log-log slope of ~1) and there was weak facilitation at low mask contrasts. Anti-phase masking was weaker (a log-log slope of ~0.7) and there was no facilitation. A two-stage model of contrast gain control (Meese, Georgeson and Baker, 2006, J. Vis, 6: 1224-1243) provided a good fit to the in-phase results and fixed its free parameters. It made successful predictions (with no free parameters) for the anti-phase results when (A) interocular suppression was phase-indifferent but (B) binocular summation was phase sensitive. Experiments II and III showed that interocular suppression comprised two components: (i) a tuned effect with an orientation bandwidth of ~±33° and a spatial frequency bandwidth of >3 octaves, and (ii) an untuned effect that elevated threshold by a factor of between 2 and 4. Operationally, binocular summation was more tightly tuned, having an orientation bandwidth of ~±8°, and a spatial frequency bandwidth of ~0.5 octaves. Our results replicate the unusual shapes of the in-phase dichoptic tuning functions reported by Legge (1979, Vis Res, 69: 838-847). These can now be seen as the envelope of the direct effects from interocular suppression and the indirect effect from binocular summation, which contaminates the signal channel with a mask that has been suppressed by the target.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1016/j.visres.2007.08.013
ISSNs: 0042-6989 (print)
Related URLs:
Keywords: dichoptic masking, grating contrast, phase, orientation, spatial frequency, binocular summation
Subjects: R Medicine > RE Ophthalmology
B Philosophy. Psychology. Religion > BF Psychology
Divisions : University Structure - Pre August 2011 > School of Psychology
ePrint ID: 48580
Accepted Date and Publication Date:
25 October 2007Published
30 May 2007Submitted
Date Deposited: 01 Oct 2007
Last Modified: 31 Mar 2016 12:25

Actions (login required)

View Item View Item

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics