title: Healthy older observers cannot use biological-motion point-light information efficiently within 4 m of themselves.
abstract: Healthy aging is associated with a number of perceptual changes, but measures of biological-motion perception have yielded conflicting results. Biological motion provides information about a walker, from gender and identity to speed, direction, and distance. In our natural environment, as someone approaches us (closer distances), the walker spans larger areas of our field of view, the extent of which can be underutilized with age. Yet, the effect of age on biological-motion perception in such real-world scenarios remains unknown. We assessed the effect of age on discriminating walking direction in upright and inverted biological-motion patterns, positioned at various distances in virtual space. Findings indicate that discrimination is worse at closer distances, an effect exacerbated by age. Older adults' performance decreases at distances as far away as 4 m, whereas younger adults maintain their performance as close as 1 m (worse at 0.5 m). This suggests that older observers are limited in their capacity to integrate information over larger areas of the visual field and supports the notion that age-related effects are more apparent when larger neural networks are required to process simultaneous information. This has further implications for social contexts where information from biological motion is critical.
authors.affiliation: Visual Psychophysics and Perception Laboratory, 3744 Jean-Brillant, School of Optometry, Université de Montréal, Montreal, Quebec H3T 1P1, Canada; e-mail:  isabelle.legault.3@umontreal.ca.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Legault
authors.forename: Nikolaus F
authors.initials: NF
authors.lastname: Troje
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Faubert
keywords: Biological motion; aging; collision avoidance; complexity