The interplay between task difficulty and microsaccade rate: Evidence for the critical role of visual load

Area of Science:

• Cognitive Psychology
• Neuroscience
• Human Factors

Background:

• Microsaccades, small rapid eye movements, are proposed as indicators of cognitive task load.
• The precise relationship between different types of task demands (visual vs. mental) and microsaccade rate remains unclear.

Purpose of the Study:

• To investigate the differential impact of visual load and mental load on microsaccade rate.
• To determine if microsaccades reflect visual or mental task demands.

Main Methods:

• Fourteen participants performed an n-back task with manipulated visual (letters vs. abstract figures) and mental (1-back to 4-back) load.
• Eye tracking, performance metrics, and subjective workload were collected.

Main Results:

• Microsaccade rate significantly increased when participants viewed abstract figures (high visual load).
• Mental load, manipulated via n-back level, did not affect microsaccade rate.
• No significant interaction was found between visual and mental load on microsaccade rate.

Conclusions:

• Microsaccade rate serves as a reliable indicator of the visual load imposed by a task.
• The findings suggest that microsaccades are not sensitive to mental workload in this context.
• Future research should explore the neural mechanisms underlying the link between visual processing and microsaccade generation.