Steady-state VEP responses to uncomfortable stimuli

Area of Science:

• Neuroscience
• Visual Perception
• Psychophysics

Background:

• Periodic visual stimuli, such as op-art, can induce visual discomfort.
• While fixational eye movements contribute to illusory motion, cortical involvement in visual discomfort is also hypothesized.

Purpose of the Study:

• To investigate the relationship between cortical electrophysiological responses and subjective visual discomfort.
• To determine if steady-state visually evoked responses (SSVEPs) correlate with visual discomfort induced by op-art stimuli.

Main Methods:

• Measured steady-state visually evoked responses (SSVEPs) to contrast-matched op-art stimuli.
• Collected subjective discomfort judgements concurrently with SSVEP recordings.
• Monitored gross eye movements using facial electrodes to rule out artifacts.

Main Results:

• Visual discomfort generally decreased with increasing spatial frequency of the op-art patterns.
• Peak SSVEP amplitudes were observed at mid-range spatial frequencies.
• A weak correlation was found between SSVEPs and discomfort for some stimuli, suggesting partial cortical contribution.
• The relationship between SSVEPs and discomfort broke down for low spatial frequency stimuli, unexplained by eye movements.

Conclusions:

• Electrophysiological responses at the cortical level partially explain visual discomfort elicited by periodic stimuli.
• The observed breakdown in the SSVEP-discomfort relationship at low spatial frequencies requires further investigation.
• Cortical processing plays a role in visual discomfort, but other factors likely contribute, especially for lower spatial frequencies.