The University of Edinburgh describes the Extended Mind Hypothesis as:
The extended mind theory says that ‘cognition’ does not just happen in our heads. Just as a prosthetic limb can become part of a body, technology such as computers (or even notebooks) become part of our minds.
Although I don’t truly believe the mind is extended through technology, I consider it an interesting point of view that resonates with me.
This idea is also referenced on the 🗒 Zettelkasten website in the article on Extend Your Mind and Memory With a Zettelkasten.