Is space special? The contribution of spatial and non-spatial event components to the construction of episodic simulations

Abstract

The overall aim of the work presented in this thesis was to provide an analysis of the constructive processes at play during episodic simulation, in terms of behavioural and phenomenological characteristics, as well as underlying neural representations. We focused on two theoretical accounts of episodic simulation: the constructive episodic simulation hypothesis (Schacter & Addis, 2007) and the scene construction theory (Hassabis & Maguire, 2007). These accounts make conflicting predictions about a range of behavioural and neural mechanisms, especially with regard to the importance ascribed to different episodic detail types (spatial vs non-spatial). Studies designed to directly compare these theoretical accounts had been sparse, despite having important implications for episodic memory and episodic simulation, as well as for hippocampal function more generally. Across two behavioural studies—examining event construction times, recall, and a range of phenomenological characteristics, including construction difficulty, and representation vividness—and one fMRI study—focusing on the representational content of the hippocampus during episodic simulation, we find converging evidence for a central role of spatial context in the construction of episodic simulation. While being broadly in line with the scene construction theory, we argue that the results are most consistent with a general relational processing account of episodic simulation. The work presented in this thesis provides novel insight into the behavioural and neural constructive processes involved in episodic simulation, and corroborates previously reported effects highlighting the central role of space. Consistent with general efforts to unify spatial and relational processing accounts, we discuss ways in which our results are coherent within an integrated framework.