Pupil reflexes generate the peripheral drift illusion due to ON/OFF motion responses

Area of Science:

• Visual perception
• Computational neuroscience
• Human vision

Background:

• The peripheral drift illusion involves apparent motion from static patterns with luminance gradients.
• Pupillary reflexes altering retinal luminance are implicated as a cause.
• Existing motion-energy models struggle to explain this illusion.

Purpose of the Study:

• To investigate if computational models of human cortical motion sensing can account for the peripheral drift illusion.
• To explore modifications to motion-sensing models that could explain the illusion.

Main Methods:

• An implementation of the Adelson-Bergen motion-energy model was used.
• A variant incorporating half-wave rectification (half-squaring) was tested.
• Model outputs were analyzed for their ability to simulate the illusory motion.

Main Results:

• The standard motion-energy model failed to account for the illusion.
• The half-squared variant successfully simulated the illusion.
• This variant creates parallel ON and OFF channels, with the OFF channel's output driving the illusion.

Conclusions:

• A modified motion-energy model with half-squaring and an OFF-channel bias can explain the peripheral drift illusion.
• This model aligns with physiological and psychophysical evidence for biased OFF-channel responses in human vision.