Motion perception during dichoptic viewing of moving random-dot stereograms.

Area of Science:

• Visual perception
• Neuroscience
• Psychophysics

Background:

• Investigating the relationship between binocular and monocular motion perception.
• Utilizing random-dot stereograms to present visual stimuli.

Purpose of the Study:

• To determine the conditions under which motion in depth is perceived.
• To explore the role of a visual frame of reference in motion perception.
• To differentiate cues for lateral motion versus motion in depth.

Main Methods:

• Subjects viewed dichoptically presented random-dot stereograms with counterphase lateral movements.
• Variable amplitude ratios were used for the left and right eye images.
• Manual tracking measured perceived lateral motion.
• A stationary reference was added in specific trials.

Main Results:

• Purely lateral motion was perceived without motion in depth when no fixed frame of reference was present.
• Perceived lateral motion magnitude equaled the algebraic mean of monocular motion percepts.
• A stationary reference was necessary to perceive motion in depth.

Conclusions:

• A visual frame of reference is essential for the perception of motion in depth.
• Lateral movements can be perceived without a visual frame of reference.
• Relative binocular disparity, rather than absolute disparity, appears to be the cue for depth perception.