via Doug Belshaw
Nostalgia, then, is a complex mental state with three components: a cognitive, an affective, and a conative component. This is generally recognised. However, my characterisation differs from the traditional one in putting imagination at its heart. First, I suggest that the cognitive component needn’t be a memory but a kind of imagination, of which episodic autobiographical memories are a case. Second, nostalgia is affectively mixed-valanced, which results from the juxtaposition of the affect generated by the act of simulating – which is typically negative – with the affect elicited by the simulated content, which is typically positive. Finally, the conative component isn’t a desire to go back to the past but, rather, a motivation to reinstate in the present the properties of the simulated content that, when attended to, make us feel good.