Age-related dedifferentiation of visuospatial abilities

Forty-eight older adults were tested on a battery of seven speeded visuospatial tasks that were developed by Chen et al. to measure the functions of the ventral and dorsal neural processing streams. Principal components analysis revealed only one factor with an eigenvalue greater than 1.0, and all of the tasks loaded heavily on this general factor. These results are in contrast to those reported in a previous study of young adults in which principal components analysis revealed two factors with eigenvalues greater than 1.0. Importantly, for young adults the second principal component was a bipolar factor which grouped the tasks based on the neural processing stream (i.e. ventral versus dorsal) whose function they had been designed to assess. The age-related difference in the factor structure of visuospatial abilities apparent from the present results may be interpreted as reflecting an age-related dedifferentiation of the neural processing streams consistent with the results of recent neuroimaging studies.