THE FREQUENCY ACCRUAL SPEED TEST (FAST) - A NEW MEASURE OF MENTAL SPEED

This paper presents a rationale for a new measure of 'mental speed', b ased on a task in which subjects discriminate the relative frequency o f flashes on one or the other of two lamps. In this 'frequency accrual speed test' (FAST), accuracy is interpreted as a measure of the rate at which hashes are registered. By assuming that sub-optimal performan ce is due to a random failure to register hashes, predictions are deri ved for a binomial and a hypergeometric version of the test. A procedu re for estimating inspection time (IT) is given, and optimal values fo r the task parameters suggested. Results from eight studies are presen ted. These show that accuracy in the FAST procedure provides a stable, reliable, and robust measure, not obviously susceptible to different strategies or to practice. In four out of six studies, accuracy in thi s type of task showed a significant positive correlation with tests of intellectual performance, and in five out of five studies accuracy wa s negatively correlated with IT (significantly in two). These results show that accuracy in the FAST procedure may provide a useful measure of the speed with which sensory information is sampled. A programme fo r further testing is outlined.