Friedrich Hayek:

In The Sensory Order: An Inquiry into the Foundations of Theoretical Psychology (1952), Hayek independently developed a "Hebbian learning" model of learning and memory – an idea which he first conceived in 1920, prior to his study of economics. Hayek's expansion of the "Hebbian synapse" construction into a global brain theory has received continued attention in neuroscience, cognitive science, computer science, behavioural science, and evolutionary psychology, by scientists such as Gerald Edelman, and Joaquin Fuster.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Before he began studying economics, what concept did Hayek come up with that was later featured in his 1952 book?
Hebbian learning