Timing deficiencies in amnestic Mild Cognitive Impairment: Disentangling clock and memory processes.

Interval timing performance in cognitive decline is typically characterized by decreased accuracy, precision, or both. One explanation for this decreased performance is a larger clock time variability. However, memory deficiencies associated with cognitive decline might also affect temporal performance in two alternative ways: First, memory deficiencies could lead to reduced encoding of just perceived durations, and thus a stronger reliance on the memory traces of previous experiences (the "prior"), yielding less precise reproductions of the most current experiences. Second, memory deficiencies could hamper the storage of perceived intervals, thus resulting in less influence of the prior. Here, we present data of 15 patients with amnestic Mild Cognitive Impairment (aMCI) and 44 healthy, aged controls, the latter split in two groups based on memory performance. All participants were tested on a temporal production task to assess clock time variability and a multi-duration reproduction task to assess the influence of memory traces reflecting current and previous experiences. Patients with aMCI showed the strongest regression towards the mean in a multi-duration reproduction task, followed by low-performing healthy controls and high-performing healthy controls, respectively. As no difference was observed between the groups in terms of clock time variability, and clock variability did not statistically contribute to the observed regression, this increased central tendency effect was not attributable to clock noise. We therefore, in line with the first explanation, conclude that memory deficiencies result in a stronger (relative) reliance on the prior.