Abstract
Contrast-negation and texture synthesis each disrupt the appearance of natural textures. Both manipulations preserve some features (e.g. isophotes in contrast-negation, summary-statistics comprising the synthesis model) while disrupting others (e.g., local phase in contrast-negation, higher-order statistics in texture synthesis). Here, we examined the extent to which contrast-negation and texture synthesis each introduce or remove critical perceptual features for discrimination from natural textures using a 4AFC oddball detection task.
Individual trials were comprised of 4 unique circular texture patches (~1 degree): 3 distracters drawn from one texture and a single target drawn from a different source. Participants had unlimited time to freely view the images and identify the target. In Experiment 1, participants (N=13) were to discriminate between synthetic and natural images of the same texture, with varying positive/negative contrast of all test stimuli, and varying oddball type (real/synthetic). In Experiment 2, participants (N=11) discriminated original from contrast-negated images of the same texture. We varied whether all test textures were natural or synthetic and also varied oddball type (positive/negative). In both experiments, we used images of food and abstract artwork in separate blocks.
In Experiment 1, synthetic oddballs were easier to identify than real ones in abstract art blocks, but harder to identify in food images (category x oddball interaction, p = 0.03). This interaction suggests that synthesized patches of natural textures have less appearance variation than patches of the original texture, but that the converse is true for synthetic images of abstract artwork (which minimizes the role of synthesis artifacts in driving the effect). In Experiment 2, we observed no main effects or interactions of oddball type, suggesting that contrast-negation does not affect the perceived variation in appearance to the same extent that texture synthesis does, even though this manipulation also compromises many of the same appearance properties of natural textures.
Meeting abstract presented at VSS 2012