Abstract

The completion of a sequence of actions in a fixed order is necessary to perform everyday activities. One line of research posits that all actions in a sequence are activated simultaneously and inhibited upon completion whereas another viewpoint suggests the successive activation of chunks of to-be-performed actions. Previous work using a sequential monitoring task indicated that chunks of items were retrieved successively from long-term memory and inhibited upon completion, suggesting a hybrid model of serial behaviour. The objective of this thesis was to examine inhibitory and chunking processes in sequential behaviour and how they change with aging. Participants learned an 8-item sequence and subsequently responded to these items in the order learnt while ignoring distractors (items out of sequence). Chunking and inhibitory processes were simulated by training participants to use overt articulation of chunked items, either with or without suppression of completed items: One group of participants continuously recited both items in each chunk in an 8-item sequence (chunking only) whereas another grouped recited both chunk items initially but subsequently updated their recital to the last item of the chunk (chunking plus inhibition). The role of chunking in sequential behaviour was supported as the chunking strategies employed resulted in similar findings as previous research. Further, suppression of previous items from conscious awareness was evident in YA compared to OA, consistent with the inhibition deficit hypothesis, which states that the ability to suppress previous task-relevant information declines with aging. Together, these results support the proposed hybrid model of sequential performance.