Microsaccades Keep the Eyes' Balance during Fixation

• Published in: Psychological science Vol. 15; no. 6; pp. 431 - 436
• Main Authors: Engbert, Ralf, Kliegl, Reinhold
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA Blackwell Publishing 01-06-2004; SAGE Publications; SAGE PUBLICATIONS, INC
• Subjects: Brownian motion; Coordination; Eye movements; Eyes; Fixation; Fixation, Ocular; Humans; Involuntary; Models, Biological; Movement perception; Posture; Random walk; Research Reports; Saccades; Saccades - physiology; Statistical analysis; Time series; Trajectories; Vision disparity; Vision, Binocular - physiology; Visual cortex; Visual perception
• ISSN: 0956-7976; 1467-9280
• DOI: 10.1111/j.0956-7976.2004.00697.x

During fixation of a stationary target, small involuntary eye movements exhibit an erratic trajectory--a random walk. Two types of these fixational eye movements are drift and microsaccades (small-amplitude saccades). We investigated fixational eye movements and binocular coordination using a statistical analysis that had previously been applied to human posture control. This random-walk analysis uncovered two different time scales in fixational eye movements and identified specific functions for microsaccades. On a short time scale, microsaccades enhanced perception by increasing fixation errors. On a long time scale, microsaccades reduced fixation errors and binocular disparity (relative to pure drift movements). Thus, our findings clarify the role of oculomotor processes during fixation.