Rich autobiographical memory recall benefits from both novelty and similarity to other daily experiences

Much existing laboratory research has shown that both novelty and prior knowledge benefit episodic memory, however they do so through differing mechanisms. Critically, autobiographical experiences are rarely completely novel or congruent with prior experience, existing somewhere within this spectrum of 'absolute' novelty to 'absolute' congruency. A prospective real-world autobiographical event sampling study was conducted to investigate this spectrum. We analyzed different types of novelty and how they predicted different episodic memory outcomes. We found that, although events that were participant-labeled as being 'new' were later remembered with greater vividness compared to 'periodic' and 'routine' events, 'new' events that were more semantically similar were recalled with the greatest vividness (what we are calling the 'something old, something new' principle). Further, participant-labeled novelty and relative semantic similarity had differing effects on the emotions associated with each event, the former increasing arousal-related emotions while the latter supported positive and minimized negative emotions. Finally, relative emotional distinctiveness predicted greater vividness and episodic detail at recall. These results suggest that different sources of novelty (i.e., participant-labeled novelty, semantic novelty, and emotional novelty) produce different effects on autobiographical memory and emotion, and that 'maximal' novelty may not lead to the greatest episodic recall later on.