Age-related differences in the detection of three-dimensional surfaces from optic flow

The present study examined age-related differences in sensitivity to optic flow for the detection of 3-D surfaces. Observers were presented with optic flow displays simulating either a 3-D corrugated surface or a random velocity pattern and were asked to detect the 3-D corrugated surface display. Performance decrements were found for older (mean age = 71) compared with younger (mean age = 21) observers across variations in density and corrugation frequency. Older observers also showed performance decrements for a motion coherence task, but performance on this task was not significantly correlated with performance on the 3-D surface detection task. These results suggest that performance on 2-D motion tasks is not necessarily predictive of performance on complex 3-D motion tasks. In addition, the results suggest that different processes underlie the analysis of 2-D and 3-D motion.