The impact of visual perspective on the formation and retrieval of memories for events

Past events can be recalled either from the perspective of one’s own eyes (i.e. firstperson perspective) or an observer perspective whereby one is able to visualize oneself inside of the mental scene (i.e. third-person perspective). Visual perspective is a central memory characteristic associated with the type of information recalled and phenomenology during retrieval. However, the majority of neuroimaging studies investigating visual perspective either do not manipulate visual perspective or focus only memories experienced from an own eyes perspective. After reviewing current theory and research on the role of visual perspective in memories for events (Chapter 1), Chapter 2 investigates the spatiotemporal dynamics of networks supporting retrieval of autobiographical events from multiple visual perspectives using a multivariate approach (Partial Least Squares Analysis). Results show that own eyes, relative to observer, perspectives engaged a core autobiographical memory retrieval network to a greater extent during later phases of retrieval. Functional connectivity analyses with an anterior hippocampal seed revealed that own eyes perspectives were also related to increased connectivity with a posterior medial network during the initial construction of autobiographical memories from observer perspectives, and stronger within-MTL connectivity during later retrieval periods from own eyes perspectives. Together, results suggest that visual perspective is an important factor in understanding how neocortical systems guide memory retrieval. Having specified neural mechanisms of autobiographical retrieval from multiple visual perspectives, I next turn to how the brain represents memories formed from own eyes and observer perspectives. While events are typically experienced from an own eyes perspective, we are also able to form memories from an observer perspective (e.g. during events with high levels of self-conscious emotion). Further, how bodily selfhood, more salient in own eyes (i.e. embodied) compared to observer (i.e. disembodied) perspectives, contributes to memory processes is not well understood. In Chapter 3, I employ virtual reality (VR) technology to manipulate perspective while creating realistic, tightly controlled memories to investigate how perspective and embodiment combine to influence patterns of neural activity underlying memory retrieval. Here, perspective was manipulated through the use of a head-mounted display unit linked to a 360° camera. Following a manipulation to alter sense of embodiment and selflocation, participants formed memories for neutral events from own eyes and observer perspectives, which were later retrieved during functional scanning. Multivariate pattern analysis revealed key differences in the neural representation of own eyes and observer memories in the angular gyrus and insula, regions crucial to establishing a coherent sense of bodily selfhood and the conscious experience of bodily sensations respectively. In Chapter 4, I continue my investigation of visual perspective during memory formation with two behavioral studies. I developed an immersive virtual reality methodology to manipulate visual perspective in realistic settings by projecting a virtual avatar into different virtual environments experienced from either an own eyes or observer perspective. Results demonstrate an increase in own eyes ratings alongside a decrease in observer ratings over time, suggesting that forming memories from an observer perspective diminishes the strength with which perspective is recalled during retrieval. Limitations and implications for all studies are discussed in Chapter 5.