Curiosity
Choosing where to go by finding where the memory is emptiest.
Like you're twelve
Drop a child into a new playground and they do not wander at random, and they do not need to be told what to look at. They go to the thing they have not seen yet. When that becomes familiar they move on. Nobody hands out points; the unfamiliarity itself is the pull.
Precisely
An associative memory reports how well it recognises each query — the fidelity of the read. Used one way, that number supports abstention: refuse to answer when the state is unfamiliar. Used with its sign flipped, the same number is a direction: move toward the least familiar state you can reach.
What comes out is directed exploration with no reward function, no map, and no new mechanism — the signal was already being computed for another purpose. An agent that always steps to its least familiar neighbour covers a space substantially faster than one stepping at random.
Two ends of the scale are degenerate, and both are diagnosable from the same number. A saturated memory recognises everything, so the gradient flattens and curiosity stalls. An empty memory recognises nothing, so every direction looks equally attractive and the choice carries no information. Curiosity is useful in between, and it stops being useful when coverage plateaus — which is a signal to stop exploring, not a failure.