Tapping sensitivity to processing in short-term memory.

This experiment examines the interference between tapping and searching in short-term memory (STM). In a concurrent processing condition, the subject first memorized a set of digits, and then executed a series of 17 taps separated by 2 s subjective time intervals. In each intertap interval, a probe was presented for comparison with the items in the memory set. The amount of processing in STM was varied from series to series by manipulating the number of items in the memory set. The results showed that mean duration and variability of intertap intervals increased proportionally with memory set size. This effect is explained by interference between processing in STM and the timing component of the tapping performance. Tapping sensitivity to memory load suggests that, under some conditions, variations in tapping performance are valid indicators of STM processing requirements of a concurrent primary task.