Exploring models of time processing : effects of training and modality, and the relationship with cognition in rhythmic motor tasks

Timing can be defined as the ability to perceive temporal sequences and regulate timed behaviors. As in other animals, our ability to make accurate time estimations is crucial in order to accomplish several activities. Organisms can process time over a wide range of durations ranging from microseconds to days. In the middle of these extremes is the hundreds of milliseconds to seconds range which is important for many everyday behaviors, such as walking, speaking and dancing. Yet, how this is managed remains poorly understood. Some central issues with regard time processing in this particular time range are whether timing is governed by one, or by several different mechanisms, possibly invoked by different effectors used to perform the timing task, as well as, if cognitive capacities are also involved in rhythmic motor timing. This thesis includes three studies. Study I investigated the effects of short- term practice on a motor timing task. Analyses of the timing variability indicated that a substantial amount of learning occurred in the first hour of practice and declined afterwards, exhibiting no trend for further decrease across the remaining 60 or 210 minutes. This effect was similar across effector, amount of feedback, and interval duration. Our results suggested that training effects influenced mainly motor precision and raised the question of whether motor timing training influenced also cognitive capacities. Study II investigated the relationship between motor timing and cognition. Specifically, participants had to train a sensorimotor synchronization task (SMS) over several days, and the question was whether this training would improve cognitive performance. A near transfer effect was found between the sensorimotor synchronization task and the sustained attention task, indicating that sustained attention is involved in motor timing. Study III compared the timing variability between the eyes and the hands, as a function of four different intervals, in order to examine whether these systems are temporally controlled by the same or different mechanism(s). The results showed several positive correlations in variability, between the eye and the finger movements, which, however, were significant only for the longer intervals. In addition, they were differences in variability between the eye and the hand, for the different interval durations. In general, the pattern of results from these studies suggested that voluntary motor timing is managed by overlapping distributed mechanisms and that these mechanisms are related to systems that manage cognitive processes, such as attention. The results partially explain the well-known relationships between cognitive ability and timing.