Aging and the use of advance probability information

Two experiments were performed to investigate the relation between age and use of advance probability information to prepare for a simple response. In both, an occasional presignal occurring about.5 sec before a possible response signal informed the subject that the probability of a response signal had increased from.1 to.5 In experiment 1, 24 women and men selected for short RT were tested, all between 21 and 78 yr of age. Subjects under 50 were able to use the advance information to shorten their RTs as were the majority of older subjects. However, for some older subjects the presignal produced a negative effect, a paradoxical lengthening of RT. In Experiment 2, using five of the older subjects from Experiment 1, more intensive testing was done with closer spacing of trials. Subjects who previously showed a lengthening of RT with the presignal now showed the typical shortening. In summary, over the age span investigated, almost all selected older subjects as well as younger subjects.