Schemata is the plural of “schema”, which is a term used in psychology and cognitive science to mean a mental framework or structure that organizes information in a useful way. Schemata make it easier to notice information that fits into these frameworks, and it also facilitates processing of new information.
In the context of music cognition, schemata play a role in the perception of larger rhythmic or musical forms. It is responsible for listener anticipation according to an established schema.
Listeners, whether through passive or active listening, internalize regularities in music to which they listen, and create a mental long-term schemata representing these regularities (Thompson, p.53)
(Definition contributed by Mike Jin, 2/3/10)