Time, interference, and rate of presentation in short-term recognition memory for items

Abstract

A list of 9 or 15 letters was presented at a rate of 1, 2, or 4 letters per second, followed by a test letter, followed by the subject's decision as to whether the test letter appeared in the previous list. The decay of trace strength was a simple exponential decay function of delay. However, the rate of decay was not constant for different rates of presentation, whether delay was measured in time or intervening items. Rather, time decay rate increased approximately linearly with presentation rate, but with a positive intercept, not a zero intercept as required by the hypothesis that delay is measured in intervening items. Decay rate for previous items appears to be greater during the time (less than 0.25 sec.) for acquisition of an item than during the time between acquisition of adjacent items.