Collinearity and surround size effects on spatial discrimination tasks

Contextual effects on fine orientation discrimination tasks

We examined the influence of context on fine orientation discrimination performance using sinusoidal grating patterns. Discrimination performance was impaired in the presence of modulated surrounds of the same spatial frequency, orientation, and contrast as the center. When center and surround were out-of-phase, separated by a gap of mean luminance, or very different in spatial frequency, perfo...

The Influence of Size of Test-Field Surround on Visual Intensity Discrimination.

Effects of foreground scale in texture discrimination tasks: performance is size, shape, and content specific.

Textural gradients can be defined as differences across space in orientation and spatial frequency content, along with absolute luminance and contrast. In this study, stimuli were created with gradients of these types to see how changing the size and shape of the foreground region affects the psychophysical task. The foreground regions were designed as clusters of target texels alternating with...

The effects of spatial proximity and collinearity on contour integration in adults and children

We tested adults and children aged 7 and 14 on the ability to integrate contour elements across variations in the collinearity of the target elements, their spatial proximity, and the relative spacing of the target elements to the background noise elements (Delta). When collinearity was high, the strength of integration for adults was largely independent of spatial proximity and varied only wit...

The effects of surround contrast on contrast thresholds, perceived contrast and contrast discrimination

Perceived contrast, contrast detection thresholds and contrast discrimination thresholds were measured in the presence and absence of surrounding patterns of a similar spatio-temporal makeup. In the foveal retina we found that the perceived contrast of the central pattern was reduced by the presence of the contrast surrounds with the effect being greatest at low test contrast. Detection thresho...