Past research has shown that adaptation to point-light walkers (PLWs) creates sex aftereffects; for example, adapting to a female PLW biases subsequently viewed PLWs to be perceived as male. In two experiments, we sought to determine whether sex aftereffects are created at a high-level in the visual system where neurons are size, location, and view invariant or at a low-level where neurons are size, location, and view dependent. In two experiments, observers adapted to exaggerated male, neutral, or exaggerated female PLWs for 8 seconds and were tested on PLWs that ranged from slightly male to slightly female for 1 second. In Experiment 1, observers adapted either to a frontal (0?°) or side (90?°) view of a PLW followed by a 0?°, 45?°, or 90?° test PLW. A biological motion sex aftereffect was found for the 0?° adapting stimulus when the test stimulus was 0?° (strong aftereffect) or 45?° (weak aftereffect). No aftereffects were observed in any of the other conditions. These results suggest that the biological motion aftereffect is view-dependent, indicating that the adaptation creating this aftereffect is at a low-level in the visual system. The lack of an aftereffect when the adaptation stimulus was 90?° may be the result of sex information being more difficult to perceive in side views. In Experiment 2, observers adapted either to a small (8?° in height) or large (16?° in height) PLW and then viewed either a small or large test PLW. A biological motion sex aftereffect was found only when the adapting and test size matched. These results show that the biological motion aftereffect is size-dependent, indicating that the adaptation creating this aftereffect is at a low-level in the visual system. Together these experiments provide strong evidence that the biological motion sex aftereffect is based on low-level, not high-level, adaptation.
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