Biological Motion Sex Aftereffects Are A Result Of Low-Level Adaptation
26.449, Saturday, May 11, 2:45 - 6:45 pm, Orchid Ballroom
Eric Hiris1, Michelle Klima1, Ryan Thompson1; 1Psychology Department, St. Mary's College of Maryland
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.