Gaze Behavior and Postural Control in Aging: The Role of Entropy in Balance Stability

Purpose: The purpose of this study was to examine the effects of gaze behavior complexity, quantified by gaze entropy, on postural control complexity, assessed using center of pressure (COP) sample entropy (SampEn), during a single-leg stance task in younger and older adults. Method: This study employed a comparative experimental design with age group (younger vs. older adults) as a between-subject factor. Participants included 15 younger adults (31.33 ± 5.74 years) and 15 older adults (66.53 ± 1.77 years), who performed a single-leg stance task under manipulated visual exploration conditions designed to vary gaze behavior complexity. Gaze entropy was adjusted by controlling the range of visual exploration, while postural control complexity was assessed using center of pressure (COP) displacement and COP sample entropy (SampEn). All variables were analyzed to examine the effects of age group, gaze entropy condition, and their interaction. Results: Gaze entropy was significantly modulated by visual exploration conditions, independent of age, confirming successful manipulation of gaze complexity. In contrast, COP displacement and SampEn were significantly greater in older adults, indicating age-related declines in postural stability and increased control irregularity. A significant interaction was observed in the mediolateral (ML) direction, with older adults exhibiting increased SampEn under conditions of higher gaze entropy. Conclusion: These findings demonstrate that visual exploration patterns influence postural regulation differently across age groups, highlighting age-related alterations in sensorimotor integration and attentional resource allocation for balance control.