Factors that affect incidental encoding during retrieval attempts: Effects of reward, retrieval processes and healthy ageing.

Abstract

A successful strategy to aid recognition is to constrain retrieval search towards a specific context in order to facilitate retrieval of goal-relevant memories. The "memory-for-foils" paradigm is used to investigate this process, termed source-constrained retrieval, by assessing whether incidental encoding of new foils during an old/new recognition test differs depending on the type of processing that was previously used during study of the old items in the test. Ageing is thought to involve impairments to cognitive control functions that support episodic memory as well as a reliance on familiarity-based recognition, suggesting that older adults will be less able to constrain retrieval search than younger adults. This thesis extends on prior source-constrained retrieval literature and explored what potential other factors could modulate the rate of incidental foil encoding. Novel factors of external reward, as well as an internal factor of item-specific retrieval processes and subjective judgments were examined, as well as how these factors are affected by healthy ageing. Contrasting to prior findings, here I show that older adults can spontaneously constrain retrieval to the same extent as younger adults, suggesting that ageing-related episodic memory decline, even in cognitively complex tasks, is not inevitable. However, there was little support for external rewards enhancing incidental encoding beyond altering response biases, despite effects of reward on motivation. Item-elicited retrieval processes however were more strongly related to foil memory, with false familiarity and heightened novelty processing for foils during an initial encounter being the most consistent predictors of increased subsequent recognition after incidental encoding. The neural ERP findings also demonstrated that spontaneous recognition processes elicited by new items have a knock-on effect on their incidental encoding, as well as succinctly showing that episodic memory tasks designated as encoding and retrieval phases are not 'process pure'