Adaptation to Speed Stress in an Immediate Memory Task

In: Human factors: the journal of the Human Factors Society, Band 13, Heft 6, S. 543-552

Abstract

Subjects identified which of eight matrices were being presented or made a "none of the above" response. The response alternatives were matrices in which each cell was filled with a color coded geometric figure, but the stimulus elements, which were presented separately, filled only one cell at a time with other cells left blank. Thus, the subjects were required to use their immediate memory prior to making a response selection. Independent variables were (1) input speed, defined in terms of stimulus element presentation rate, and (2) stimulus complexity, defined in terms of matrix size. Subjects were given a large number of performance trials. Results showed that extensive practice reduces the time required to respond accurately to a set of stimulus elements; the more complex the stimuli, the smaller the reduction. Whenever the minimal response time was surpassed, both performance accuracy and the amount of information transmitted per minute fell to a degree that was disproportionately greater than increases in input speed relative to the minimal response time (channel capacity). Apparently, subjects tended to recirculate information in immediate memory even when overloaded. Response times related to performance accuracy indicated that when the number of stimulus elements in immediate memory exceeded seven, chances of a correct response were practically zero, with sharp decrements occurring when five stimulus elements were being handled.