Contrast gain-control in stereo depth and cyclopean contrast perception

Area of Science:

• Vision Science
• Computational Neuroscience
• Perceptual Psychology

Background:

• Human observers perceive depth from stereograms even with significant interocular contrast differences.
• The precise role of contrast gain control in stereo depth perception remains under-investigated.
• A multipathway contrast gain-control model (MCM) previously explained binocular phase and contrast perception.

Purpose of the Study:

• To extend the MCM to simultaneously explain stereo depth and cyclopean contrast perception.
• To systematically investigate the function of contrast gain control in stereo depth perception.
• To model how independent contrast manipulation in each eye affects depth and perceived contrast.

Main Methods:

• Dynamic random dot stereograms (RDS) with manipulated contrasts (0.08-0.4) were presented to each eye independently.
• Disparity thresholds for depth perception were measured.
• Perceived contrasts of cyclopean images were quantified.

Main Results:

• Both disparity thresholds and perceived contrast were strongly dependent on the signal contrasts in each eye.
• These findings demonstrated characteristic binocular contrast gain-control properties.
• An extended MCM accurately accounted for the observed data (r² = 0.945).

Conclusions:

• The extended MCM posits mutual gain control between eyes based on signal contrast energy.
• Stereo strength is proportional to the product of signal strengths post-gain control.
• Perceived contrast is calculated by combining contrast energy from both eyes, successfully explaining experimental and literature data.