Stereopsis impairment during smooth pursuit eye tracking

Area of Science:

• Visual perception
• Neuroscience
• Psychophysics

Background:

• Coherent motion of random dot patterns can impair stereograting perception.
• This impairment is often associated with optokinetic nystagmus.

Purpose of the Study:

• To investigate the underlying cause of stereograting perception impairment during coherent dot motion.
• To test hypotheses involving efferent-afferent interactions versus temporal integration.

Main Methods:

• Experimental manipulation of visual displays and conditions to differentiate between proposed mechanisms.
• Determination of spatial frequency and angular velocity thresholds for stereopsis cessation.
• Testing the temporal integration hypothesis using displays with bisected disparity values.

Main Results:

• The efferent-afferent interaction hypothesis was rejected; stereopsis remained intact under modified conditions with optokinetic nystagmus.
• A constant limiting alternation rate (spatial frequency x angular velocity = 7.2 cycles/s) was identified for stereopsis cessation.
• Evidence supported a temporal integration process, as bisected displays with different disparities yielded averaged perceived depth levels.

Conclusions:

• The impairment in stereograting perception is primarily caused by a temporal integration process.
• This process averages alternating disparity values of moving dots at the temporal resolution limit of stereoscopic mechanisms.