The effect of age upon the perception of 3-D shape from motion
43.317, Monday, 19-May, 8:30 am - 12:30 pm, Jacaranda Hall
Jacob Cheeseman1, J. Farley Norman1, Jessica Pyles1, Michael Baxter1, Kelsey Thomason1, Autum Calloway1; 1Department of Psychological Sciences, Ogden College of Science and Engineering, Western Kentucky University
In previous research, we evaluated the ability of older, middle-aged, and younger adults to discriminate the 3-dimensional (3-D) shape of curved surfaces defined by optical motion. Temporal correspondence was disrupted by limiting the lifetimes of the moving surface points. It was found that in order to discriminate 3-D surface shape reliably, the younger and middle-aged adults needed a surface point lifetime of approximately 4 views (in the apparent motion sequences). In contrast, older adults needed a much longer surface point lifetime of approximately 9 views in order to reliably perform the same task. In the current experiment, the negative effect of age upon 3-D shape discrimination from motion was replicated. In this experiment, however, 20 younger and older participants' abilities to discriminate grating orientation and speed were also assessed. Edden et al. (2009) have recently demonstrated that behavioral grating orientation discrimination correlates with GABA (gamma aminobutyric acid) concentration in human visual cortex. Our current results demonstrate that the negative effect of age upon 3-D shape perception from motion is not caused by impairments in the ability to perceive motion per se, but does correlate significantly with grating orientation discrimination. This finding suggests that the age-related decline in 3-D shape discrimination from motion is related to decline in GABA concentration in visual cortex.