Exploring cognitive and neural substrates of search and foraging behaviour across the lifespan: from younger to older adults

Abstract

Research suggests that search and foraging behaviours serve as valuable markers for pathological ageing. However, existing tasks have been limited to two-dimensional settings, neglecting additional cues and reference frames. To address this gap, a comprehensive plan of research was developed to establish a new three-dimensional paradigm, drawing from and integrating search traditions with foraging principles. This paradigm was then tested with older adults alongside neuropsychological profiling. Across seven experiments, this thesis investigates whether the neural and cognitive foundations of search and foraging behaviour can be predicted using a large-scale immersive virtual reality (VR) task, exploring the essential roles of executive and cognitive control mechanisms in achieving success. Chapter 3 introduces the novel VR task, which manipulates template provision and target distribution. The results suggest that fully motile three-dimensional search is guided by visual cues in a manner similar to two-dimensional visual search, challenging previous notions that large-scale search relies less on visual cues. Additionally, measures of cognition indicate that executive control supports performance in challenging tasks, whilst episodic memory aids lighter cognitive load conditions. In Chapter 4, the VR paradigm is implemented with both older and younger adults, accompanied by structural MRI and cognitive assessments. The findings reveal non-significant differences in search or foraging performance between age groups. However, older adults with atypical cognitive ageing profiles exhibit less efficiency compared to typical counterparts, particularly in cued inspections and target collection, with higher white matter connectivity predicting success. Chapter 5 delves into the explicit role of executive function and cognitive control through a task inspired by set-shifting paradigms, demonstrating greater shifting success when guided by greater executive control. Chapter 6 explores unexpected results from the cognitive screening procedure in greater depth. The final chapter contextualises the findings within existing literature and evaluates the paradigm's place amongst other attempts to integrate insights from search and foraging traditions.