Contrast gain control determines global form percept in tripole Glass patterns

Area of Science:

• Visual perception
• Computational neuroscience
• Psychophysics

Background:

• Glass patterns demonstrate global form perception from local elements.
• Perception involves local dipole association and global grouping processes.
• Existing models struggle to explain contrast effects in Glass pattern perception.

Purpose of the Study:

• To investigate the impact of luminance contrast on global form perception in Glass patterns.
• To utilize a novel tripole variant of Glass patterns to isolate perceptual effects.
• To develop and test computational models for contrast-dependent Glass pattern perception.

Main Methods:

• Participants viewed Glass patterns composed of tripoles with manipulated context dot luminance contrast.
• The probability of judging patterns as a clockwise (CW) spiral was measured.
• Data was analyzed to determine the relationship between contrast and perceptual judgments.

Main Results:

• A tripole Glass pattern's CW spiral perception probability exhibited an inverted U-shaped function with increasing CW context dot contrast.
• Higher contrast in competing counterclockwise (CCW) context dots shifted the peak of the inverted U-shape.
• Existing Glass pattern models failed to account for these contrast-dependent results.

Conclusions:

• Luminance contrast significantly modulates global form perception in Glass patterns.
• A divisive inhibition model accurately describes the observed contrast effects.
• This suggests a neural mechanism where competing stimuli mutually suppress perceptual responses.