A schema is a configuration within the brain, either inborn or learned, against which the input of the nerve cells is compared.... the conscious mind... can fill in details that are missing from the actual sensory input and create a pattern in the mind which is not necessarily present in reality. In this way, the gestalt of objects—the impression...—is aided by the taxonomic powers of the schemata.

On Human Nature (1978) - Ch.4 Emergence