Abstract
A form of recall is discussed in which some elements of an event serve to initiate recall of the whole set of elements which comprised an event. The conditions which enable learned associations between pairs of elements to be used for such recall are quantitatively assessed for recall procedures which use only direct associations from the initial elements ('simple recall') and which use both direct and indirect associations ('progressive recall'). The theory is equivalent to the analysis of a neural model in which randomly arranged excitatory connections between a set of cells can be strengthened by simultaneous activity in their presynaptic and postsynaptic elements. The problems involved in a direct neural implementation of the model are discussed, and it is seen that some of the mechanisms resemble known physiological mechanisms in the cerebral cortex. The relationship between recall and recognition learning is discussed and the evidence relating these functions to the hippocampal formation is assessed.