Long lasting indirect memory performance for abstract shapes in amnesics and matched controls.

The speed with which subjects copied complex geometrical shapes was used as an indirect memory measure in a group of 12 organic amnesics of several aetiologies and their matched controls, tested at two delays. Both subject groups were found to copy previous seen shapes faster than new foil shapes, and the magnitude of the speed up effect did not differ significantly between amnesics and matched controls when tested at two delays of 10 min and 24 hr, respectively. The size of the indirect memory effect did not decline across the delay in either group. In contrast to indirect memory performance, measured by two-choice recognition of the shapes, was impaired in the amnesic group and there was some suggestion that recognition performance declined across the delay in both subject groups.