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Accessing Memory Representations

All retrieval in the Matrix Model is direct. The memory matrix is presented with cues and access occurs in parallel. There is no sequential search process. Presenting the model with a cue involves taking the inner product (or dot product) of the cue vector with the memory matrix.

Matching versus Retrieval Tasks: This distinction is captured in the Matrix Model by the nature of the tensor that results once all cues have been applied. If the resultant tensor is a scalar we are dealing with a matching process. This scalar can be compared against criteria to determine a yes/no or rating value. If the resultant tensor is a vector then we have a retrieval process. The vector can be compared against all item vectors with the item being the output of the process.

Episodic versus Semantic Tasks: In episodic tasks, a reinstated context vector is used as a cue. In semantic (generalized) tasks, a vector which is equally similar to all contexts is used so as to average over all experiences with the cue items (typically, this is a vector with all components set to 1/n where n is the dimension of the vector).