Preparatory interval influences on reaction-time of elderly adults.

The influence of regularity of preparatory interval (PI) on simple reaction-time (RT) in elderly persons was studied in a sample of 25 women between 65 and 88 years of age. RTs to regular and variable PIs of 1, 3, 7, 9, and 13 seconds were compared using Steffy's embedded isotemporal blocks method. The advantage of PI regularity was lost at 13 sec, where performance was faster for irregular trials. The RT-PI functions were similar to those found by Botwinick and his associates who used Shakow's paradigm, even though overall RT was slower in this sample. The similarity of results across the two paradigms suggest that the point of RT function crossover is interval dependent and unrelated to response latency in elderly adults.