Explicit and implicit timing in older adults: Dissociable associations with age and cognitive decline

This study aimed to test two common explanations for the general finding of age-related changes in temporal processing. The first one is that older adults have a real difficulty in processing temporal information as compared to younger adults. The second one is that older adults perform poorly on timing tasks because of their reduced cognitive functioning. These explanations have been mostly contrasted in explicit timing tasks, where participants are overtly informed about the temporal nature of the task. Fewer studies have instead focused on age-related differences in implicit timing tasks, where no explicit instructions to process time are provided. Moreover, the comparison of both explicit and implicit timing in older adults has been restricted to healthy aging only. Here, a large sample (N= 85) of healthy and pathological older participants completed explicit (time bisection) and implicit (foreperiod) timing tasks. Participants’ age and general cognitive functioning, measured with the Mini-Mental State Examination (MMSE), were used as continuous variables to explain performance on explicit and implicit timing tasks. Results showed a clear dissociation between the effects of healthy cognitive aging and pathological cognitive decline on processing of explicit and implicit timing. Whereas age and cognitive decline similarly impaired the non-temporal cognitive processes (e.g., memory for and/or attention to durations) involved in explicit temporal judgements, processing of implicit timing survived normal age-related changes. These findings carry important theoretical and practical implications by providing the first experimental evidence that processing of implicit, but not explicit, timing is differentially affected in healthy and pathological aging.