You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Friedrich_Hayek

Context:
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.

Question:
Before he began studying economics, what concept did Hayek come up with that was later featured in his 1952 book?

Hebbian learning