[The overestimation of performance: a specific bias of aging?]

The decline of postural abilities with age leads to increased falls. In this study, we suggest that a disturbance in the perception of postural affordances, characterized by an overestimation of performance, could be a major risk of falls specifically in the elderly. In addition, we test the possible link between the overestimation of capabilities and postural balance as we know degraded in the elderly. A group of 10 young subjects (M = 24.2 years ± 2.04) and a group of 10 elderly subjects (M = 75.9 years ± 5.7) must evaluate, without action, the maximum height of an obstacle that they can stride over. Then their postural performances are measured. The results show that, contrary to young people who correctly evaluate their performance (difference of 1.75 cm between estimated performance and real performance), older participants overestimate their maximum height of crossing over (12.5 cm difference between performance and estimated real performance). Moreover, the overestimation of performance is associated with poor postural stability. The bias of overestimation may stem from a lack of updating of motor programs caused by a functional brain change with age and/or lack of exercise who reduces updating by trial and error.