Effects of feedback on time production errors in aging participants

In two experiments, healthy participants ages 60 years and older provided peak-interval time production data for two target intervals (6 and 17 s) over 2 days (baseline and retest sessions). In Experiment 1, three groups of participants were provided with two types of feedback during the baseline session that assisted either decision criteria setting or memory updating. During the retest session, run after a 24-h delay, each group received either one of the two types of feedback, or no feedback at all. Experiment 2 varied three additional groups' feedback during the baseline session only. Results indicated that the duration-dependent timing errors previously associated with aging did not occur during the retest session with the decision-criteria feedback regimen, or during the baseline session even in the complete absence of feedback. Thus, testing following the delay and without decision-criteria feedback are the necessary and sufficient conditions for the expression the timing errors in aging. The efficacy of memory updating feedback could not be established. The discussion contrasts these results with the conditions that produce abnormal timing in Parkinson's disease patients in a similar procedure. (C) 2007 Published by Elsevier Inc.