A reconsideration of age-related reaction time slowing from a learning perspective: Age-related slowing is not just complexity-based

In this article the authors provide a detailed examination of the factors that influence the function relating young subjects' reaction time to that of older subjects. The authors examine the often cited Complexity Hypothesis according to which older adults are proportionally slower than young adults as a function of the complexity of the task being performed. The authors review data suggesting that age differences in response time are a function of the type of practice (consistent or varied mapping), the amount of practice, and the structure of the task. This review suggests that grouping these factors under a label of "complexity" may actually decrease their predictive utility. Furthermore, the results suggest that the learning that occurs as a function of practice changes the relationship between the reaction times of young and old adults. The implications of the findings are discussed in terms of theoretically-driven distinctions for making predictions of old adults' performance from that of young subjects.