Process-specific slowing with advancing age: evidence derived from the analysis of sequential effects.

In the current study we examined the generalized slowing hypothesis on the mechanisms underlying sequential effects in serial two-choice reaction time tasks. For young adults, sequential effects of conditions with a high and a low stimulus presentation rate respectively pointed to an automatic and an expectancy mechanism. Older adults' low presentation rate data corroborated the general slowing hypothesis for expectancy, whereas the high presentation rate results did not. The observation of a differential influence of age on the automatic and the expectancy mechanism poses a problem for notions assuming that higher level processes are more vulnerable to advancing age than lower level processes.