Evolution and Episodic Memory: An Analysis and Demonstration of a Social Function of Episodic Recollection

Over the past two decades, an abundance of evidence has shown that individuals typically rely on semantic summary knowledge when making trait judgments about self and others (for reviews, see Klein, 2004; Klein, Robertson, Gangi, & Loftus, 2008). But why form trait summaries if one can consult the original episodes on which the summary was based? Conversely, why retain episodes after having abstracted a summary representation from them? Are there functional reasons to have trait information represented in two different, independently retrievable databases? Evolution does not produce new phenotypic systems that are complex and functionally organized by chance. Such systems acquire their functional organization because they solved some evolutionarily recurrent problems for the organism. In this article we explore some of the functional properties of episodic memory. Specifically, in a series of studies we demonstrate that maintaining a database of episodic memories enables its owner to reevaluate an individual's past behavior in light of new information, sometimes drastically changing one's impression in the process. We conclude that some of the most important functions of episodic memory have to do with its role in human social interaction.