“In the mind’s eye” – Exploring the interaction between oculomotor behaviour and memory-related processes in ageing and neurodegeneration

Abstract

Much of the rich internal world constructed by humans is derived from, and experienced through, visual mental imagery. Despite growing appreciation of visual exploration in guiding imagery-rich construction-based processes, extant theories of memory retrieval and prospection have yet to accommodate the precise role of visual mental imagery and corresponding oculomotor dynamics in the service of past and future-oriented thinking, particularly as we age and in the presence of neurodegenerative syndromes.

This thesis comprises three experimental studies investigating these issues. Chapter 2 demonstrates distinct signatures of oculomotor behaviour during visual exploration and memory retrieval in younger and cognitively healthy older adults, as well as patients with Alzheimer’s disease or semantic dementia. In Chapter 3, I further demonstrate age-related changes in eye movement metrics during the endogenous construction of atemporal scenes in the absence of externally cued visual stimuli. Results suggest a shift away from the production of eye movements in older adults as a function of increasing task complexity as cognitive demands exceed working memory capacities. Finally, Chapter 4 expands on the preceding findings in the context of episodic future thinking. The temporal distance and the level of plausibility of hypothetical future events are found to influence participants’ performance by encouraging the elaboration of scenarios that are particularly rich in contextual detail in selected experimental conditions.

The work presented in this thesis adds to the extant literature by demonstrating and characterising the relationship between oculomotor behaviour and imagery-rich construction-based processes. Future enquiries exploring the potential and diverse applications of oculomotor metrics to neuropsychological and clinical research will further elucidate the complex adaptive mechanisms supporting cognitive performance in both healthy ageing and neurodegeneration.