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Karin Pilz, Patrick Bennett, Allison Sekuler; Aging disrupts the processing of point-light walkers presented in noise. Journal of Vision 2009;9(8):616. doi: 10.1167/9.8.616.
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Previous studies have shown that older subjects have a decreased ability to discriminate the walking direction of point-light walkers. The current experiments examined the cause of this age difference. Younger (18–32 years) and older ([[gt]]60 years) subjects discriminated the walking direction of upright and inverted walkers across a range of stimulus durations. In Experiment 1, walkers were embedded in scrambled-walker noise. This type of masking forces observers to discriminate the walker's direction on the basis of the global configuration of the walker's points. Older subjects performed significantly worse than younger subjects, especially when the walkers were inverted. Similar results were obtained in Experiment 2, in which walkers were embedded in a dynamic random noise mask. To investigate whether older people rely more on local motion information than young observers, in Experiment 3 we examined performance with three kinds of walkers that provided observers either with only local motion information, only global form information, or both kinds of information (normal walkers). All walkers were presented in the absence of any noise. There was only a marginally significant effect of age, but overall, older observers performed significantly worse for inverted walkers in all conditions. In addition, older observers exhibited decreased performance for normal walkers, which could mainly be ascribed to the inverted condition. Manipulation of the sources of information on upright walkers had similar effects on response accuracy in older and younger subjects in all conditions. Overall, the results suggest that the age-related decrease in performance for discriminating point-light walkers is mainly due to a decreased ability for older observers to extract relevant information from noisy or unfamiliar displays, and not necessarily because older and younger subjects use different kinds of information available in the stimulus.
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