Microsaccades during high speed continuous visual search

Area of Science:

• Neuroscience
• Cognitive Psychology
• Ophthalmology

Background:

• Microsaccades are small, rapid eye movements crucial for visual processing.
• Understanding their role in continuous visual search is essential for explaining visual perception efficiency.

Purpose of the Study:

• To analyze microsaccade behavior during continuous visual search and targeting of faces.
• To investigate the influence of background complexity and target eccentricity on microsaccade activity.
• To determine if microsaccades serve perceptual functions during visual search tasks.

Main Methods:

• Participants performed continuous visual search for upright or inverted faces in cluttered or simple backgrounds.
• Eye movements, including microsaccades and saccades, were recorded as participants targeted faces.
• Microsaccade rates and distributions were analyzed in relation to stimulus onset and saccade offsets.

Main Results:

• Microsaccade rate dropped to near zero within 12 ms of stimulus onset, irrespective of background or target eccentricity.
• Microsaccades were rarely observed between stimulus onset and the first saccade to the target.
• Approximately 20% of trials featured a single post-saccadic microsaccade, task-oriented towards facial landmarks.

Conclusions:

• A single feedforward pass through the visual hierarchy may suffice for prolonged continuous visual search.
• Microsaccades can fulfill perceptual roles, such as saccade correction or achieving task-oriented goals in continuous visual search.