Abstract
Purpose: To investigate how hue is coded for purposes of processing texture. Specifically, we test a model proposing that hue-selective units all share tuning functions of the same shape F but centered on different hues so as to achieve uniform coverage around the hue circle. Methods: We used eight equiluminant hues drawn from a circle of maximal achievable radius on our monitor in an equiluminant plane of DKL space. Different textures (hue scrambles) were created by randomly mixing small squares of these 8 hues in varying proportions. On a trial, the participant strove to detect the orientation of a square wave whose texture-defined bars alternated between two different hue scrambles. In a given condition, the difference between the histograms of the two textures to be discriminated on a given trial was always strongly correlated with a particular "seed" histogram difference D. We measured the influence ID(h) exerted by different hues h on the participant’s judgments. Results: The model being tested predicts that ID should be the convolution of D with some tuning curve F. This prediction was supported for several different seeds D. For one participant the tuning curve F fell to half-height over an angle of around p/4 around the hue circle; for the other observer, F fell to half-height over an angle near p/2. Conclusions: For purposes of texture processing, hues are coded by the activation produced in an ensemble of units all with tuning curves sharing the same, fairly broad shape but centered on different hues uniformly around the hue circle.
Meeting abstract presented at VSS 2012