Fixational Eye Movement as a Window Into the Human Mind: The Neural Basis and Cognitive Role of Microsaccades

Microsaccades – rapid, fixational eye movements typically smaller than 1° – play a crucial role in maintaining visual stability and are increasingly recognized as indicators of internal neurological states. Classical studies and recent evidence indicate that microsaccade timing and rate are closely linked to attentional shifts and task demands, highlighting their functional significance. However, methodological inconsistencies in definitions and detection parameters continue to challenge interpretation. Converging findings across behavioral, neural, and computational studies support the use of microsaccades as precise, noninvasive probes of perception, attention, and cognition. This review synthesizes decades of research along four main dimensions: the kinematics and definition of microsaccades, their neural control mechanisms, links to cognitive and affective processes, and methods for their detection and analysis, including emerging high-speed and event-based sensors. We also identify open challenges, including the need for standardized criteria, robust model-based detection at kilohertz rates, and advanced event-based tracking. Addressing these challenges will enable microsaccades to serve as a reliable window into the dynamics of neural and cognitive processes. We conducted a systematic search to identify papers for this review. Sources: Google Scholar, Scopus, PubMed. Search terms included "microsaccade", "fixational eye movements", AND "eye tracking", and combinations with "detection", "Engbert", "Bayesian", "event camera" "SPAD". We included peer-reviewed articles, conference proceedings, and publicly available benchmarks. Inclusion: empirical studies reporting microsaccade kinematics, neural mechanisms, detection algorithms, or cognitive/clinical applications; review/editorial pieces only when they provided synthesis. Exclusion: studies that did not report primary microsaccade data or were peripheral to fixation (e.g., large saccade-only papers). This procedure was chosen to maximize coverage of influential works while maintaining transparency for replication.