6 ideas
Each period has modelled remembering on the most advanced recording or storage device it had: the wax tablet, then writing and the library, then the photograph, phonograph, hologram and computer. Theories of memory therefore change mainly when new artificial memories are invented, not when new facts about the brain are discovered.
A memory metaphor is a working heuristic, not decoration. It carries built-in assumptions that set which questions get asked and which phenomena count as explanation. Storage-and-retrieval metaphors highlight preservation and fidelity, and they push forgetting, distortion and reconstruction to the margins as mere defects.
In the Theaetetus, perception presses into the mind the way a signet ring presses into wax. The wax's quality explains individual differences: hard, soft, pure or muddy wax gives memories that are slow, quick, lasting or blurred. False judgment is a percept matched to the wrong imprint, like a foot put into the wrong footprint.
Francis Galton exposed many faces onto one photographic plate, producing a composite that looked like a 'type' of no single person. The technique became a model for general ideas: repeated overlapping impressions reinforce shared features and wash out individual ones. On this model, a concept is a blurred average of many specific memories.
The Wunderblock, a toy writing pad, solved a puzzle Freud found in memory: the mind must stay endlessly receptive and still keep permanent traces. The pad does both by separating layers. This maps onto a perceptual system that retains nothing and a deeper system that stores everything.
A hologram spreads information about the whole image across the entire plate, so any fragment can still reconstruct the full picture at lower resolution. The metaphor was used to explain why brain lesions rarely erase specific memories. On this view, memories are not stored at single locations but spread across the whole tissue, and they degrade gracefully instead of vanishing.