ACCURACY AND SPEED OF MEMORY IN DEPRESSED AND ORGANIC AGED

Forty‐three subjects aged 50 and over were tested on a Sternberg recognition‐memory task to explore the relative effects of depression and altered brain function on short‐term memory in later life. Organic, depressed, and control subgroups were compared on accuracy and speed of response. Speed‐of‐memory scanning was differentiated from other speed‐of‐response components; separate estimates of memory efficiency and subjective response criteria were calculated from accuracy data by signal‐detection methods. Organic subjects performed much less accurately and quickly than others, showing great variability of response speeds. Depressed subjects performed less accurately and quickly than controls, particularly on negative trials, but did not differ in rate of memory scanning. Depression was associated with poorer memory efficiency and laxer response criteria (greater tolerance for false‐positive errors). Slower and less accurate responding was also associated with a poorer educational background. Many performance differences were best accounted for by the additive effects of depression and educational background, rather than by either variable individually. The association of laxer criteria with depression alone, however, was discussed in terms of a possible acquiescent response bias in depression.