Despite a strong intuitive and theoretical tradition linking autobiographical memory and sense of self, there are few coherent, testable models that exemplify how these constructs relate. Without any clear theoretical starting point, research efforts have been fragmented, with many different fields of psychology operating in relative isolation, using different methodological approaches and a confusing array of self-related terminology. We attempt to bridge the widening gap between theory and research by proposing a novel framework for sense of self and memory. This simple model delineates sense of self along 2 dimensions: the subjective versus objective and the present versus temporally extended aspects of sense of self. The 4 resulting components of sense of self are argued to relate to autobiographical memory in important, but very different, ways. Subjective sense of self provides a crucial precondition for episodic memory, which in turn is a prerequisite for phenomenological continuity. Autobiographical memory, and particularly its semanticized forms, are important for the formation and maintenance of a mental representation of the objective self in the present moment and across time. This model does not represent a new theoretical direction for the study of sense of self and memory; to the contrary, it is deeply grounded in the theoretical work of the past few decades. Its novelty is that it translates this theoretical groundwork into a form that is readily accessible for researchers. We review evidence for our model and suggest ways that it may provide a roadmap for future research efforts.

Diachronic unity is the belief that, despite changes, we are the same person across the lifespan. We propose that diachronic unity is supported by the experience of remembering the self over time during episodic recall (i.e., phenomenological continuity). However, we also predict that diachronic unity is also possible when episodic memory is impaired, as long as the ability to construct life narratives from semantic memory (i.e., semantic continuity) is intact. To examine this prediction, we investigated diachronic unity in Alzheimer's Disease (AD) and amnestic mild cognitive impairment (aMCI), two conditions characterised by disrupted phenomenological continuity. If semantic continuity is also altered in these conditions, there should be an associated deterioration in diachronic unity. Participants with AD, aMCI, and healthy controls (HC) completed a self-persistence interview measuring diachronic unity (beliefs about self-persistence, explanations for stability/change). Semantic continuity was assessed with a life-story interview measuring autobiographical reasoning (self-event connections), and coherence (temporal/thematic/causal) of narratives. Our results highlight a complex relationship between semantic continuity and diachronic unity and revealed a divergence between two aspects of diachronic unity: AD/aMCI groups did not differ from HC in continuity beliefs, but AD explanations for self-persistence were less sophisticated. Semantic continuity was most impaired in AD: their narratives had fewer self-event connections (vs. HCs) and lower temporal/thematic coherence (vs. HC/aMCI), while both AD/aMCI groups had lower causal coherence. Paradoxically AD participants who scored higher on measures of beliefs in the persistence of the core self, provided less sophisticated explanations for their self-persistence and were less able to explore persistence in their life narratives. These findings support the importance of semantic continuity to diachronic unity, but suggest a more nuanced and multifaceted relationship than originally proposed in our model. In AD, diminished life narratives that retain features of cultural life scripts are sufficient for strong subjective beliefs of self-persistence, but not for sophisticated explanations about persistence. Better semantic continuity, with the ability to weave high-quality life narratives, may scaffold the capacity to understand and explain one's diachronic unity, but this produces less surety about self-persistence.