Older subjects responded slower than younger subjects on a spatial task which required them to rotate mentally a perspectively drawn figure in order to judge whether it was congruent with a second figure. Decision time was partitioned into two components: (1) the time taken for the “mental rotation” process, (2) the time taken for the remaining processes such as stimulus encoding and motor output. Both components required more time in the elderly group. The increase with age in the component of decision time representing rotational processes was similar to those increases seen by other investigators examining agedependent differences in time required for memory-scanning processes using verbal stimuli.