PROCESSING TIME DECLINES EXPONENTIALLY DURING CHILDHOOD AND ADOLESCENCE

One hundred ninety-two 7.5- to 21-year-olds and 384 adults (17- to 43-year-olds) were tested on six speeded tasks: (a) a simple response time task in which they released a button upon presentation of a stimulus, (b) a tapping task in which they pushed a button as rapidly as possible for 5 s, (c) a pegboard task in which they transferred 10 pegs from one row to another, (d) a modified form of the coding subtest from the Wechsler Intelligence Scale for Children (WISC), (e) a matching task in which they judged if pairs of pictures were identical physically or in name, and (f) a mental addition task in which they judged the accuracy of problems such as 2 + 3 = 6. Age-related change in processing time on most of these tasks was well described by a single exponential function. Results are interpreted in terms of a central mechanism that limits speeded performance and that changes with age.