Sequential motor skill: cognition, perception and action

Discrete movement sequences are assumed to be the building blocks of more complex sequential actions that are present in our everyday behavior. The studies presented in this dissertation address the (neuro)cognitive underpinnings of such movement sequences, in particular in relationship to the role of perceptual information and the development of automaticity in such skill. The majority of the empirical chapters focusses on the role of perceptual information in sequential behavior, and specifically examines the context-dependence of sequencing performance. The notion of context-dependence – which originates from the literature on verbal memory, but has also been reported for motor skill – holds that memory retrieval is better in the environment in which the memory trace was initially acquired as opposed to retrieval in a different environment. First, a new form of context-dependence is explored, namely context-dependent filtering. It was investigated whether the continuous pairing of an irrelevant stimulus along with imperative stimulus results in the learning of (filtering out) the irrelevant information. If this would be the case, sequencing performance is assumed to be hindered when the learned pairs of irrelevant and imperative stimuli are changed during testing. Second, the notion of context-dependence for memory-based sequencing skill was studied, specifically differentiating between the sensitivity to perceptual changes of sequence preparation versus execution processes. These chapters on the effects of perceptual changes on sequencing performance also address the role of practice in this matter. In another chapter, developmental differences regarding the cognitive mechanisms underlying discrete sequence skill were investigated by studying whether preadolescent children, like young adults, learn to perform sequential movements in an automatic fashion. Previous studies demonstrated that the development and use of motor chunks for sequencing performance was limited in middle-aged and elderly. It has been suggested that this relates to the degeneration of frontal and other brain areas with older age. As these areas are known to mature during childhood, it could be hypothesized that sequencing skill differs between children and young adults as well. Finally, the neural basis of sequencing performance was addressed. The changes with practice in cognitive processes underlying sequence production were related to changes in brain areas that are involved in the production of discrete movement sequences.