Abstract
Numerous experimenters have posited a strong link between subjective appearance and performance on different low-level visual tasks. It has been suggested that the subjective appearance of stimulus components in center-surround masking experiments act to segregate the components. The current experiment was designed to systematically measure the effect of real (mean luminance difference between center and surround) or illusory (contrast, phase, spatial frequency, or orientation differences between center and surround) contours on the psychometric functions of center-surround masking of suprathreshold orientation discriminations. Correlated changes in the psychometric functions’ shape and position would suggest that the mechanism responsible for reducing or removing masking effects in center-surround stimuli responds to contours, independent of how they were created (higher-level processing). Uncorrelated changes in shape and position would suggest a mechanism that treats information from first- and second-order channels differently. It is also possible that illusory contours created by different dimensions may produce different results. This would be even more support for differential processing of low-level spatial information. The results indicate significant shifts in the shape and position of the psychometric functions for all dimensions, from low levels of texture segregation to high levels of texture segregation. At their highest level of texture segregation there is no significant difference between the shape and position of the curves. This suggests that texture segregation plays a large role in the reduction of masking in center-surround stimuli; independent of how the components are segregated.