CONCEPT
External Representations
Diagrams, maps, sketches, timelines, and organizational charts understood not as passive displays but as active cognitive tools that shape and constrain the thoughts their users can have.
External representations — the artifacts humans construct to make spatial structure visible outside the head — are not neutral containers for pre-existing thought. They are active participants in cognition. A timeline forces sequential thinking. A hierarchy forces categorical thinking. A network enables relational thinking that pure text struggles to carry. Tversky's research demonstrates that changing the representation changes what the thinker can think. The affordances of the external tool determine which inferences become easy, which become difficult, and which become nearly impossible. This is why the choice of representation in AI collaboration is not a presentation issue but a cognitive one.
In The You On AI Field Guide
The tradition runs from Euclidean geometry — whose proofs depend on diagrams that carry information the propositions alone do not — through modern data visualization. Edward Tufte's principle that graphical excellence gives the viewer the greatest number of ideas in the shortest time captures the efficiency gain external representations offer when well-constructed. But Tversky's insight is deeper: the