Non-associative learning is learning that occurs in the absence of any particular outcome, such as a reward or punishment. One type of non-associative learning is habituation, which is the reduction or elimination of a behavioral response to a repeatedly presented stimulus. Chicks presented with silhouettes flying overhead provide an example. Initially, any overhead silhouette provokes a defensive crouching posture, but eventually, chicks habituate to overhead silhouettes that have proved not to be threatening. In the absence of any consequences, chicks no longer crouch in response to a harmless silhouette passing repeatedly overhead.

Sensitization is another form of non-associative learning. Sensitization is the enhancement of a response to a stimulus that is achieved by presenting a strong or novel stimulus first. This first stimulus makes the animal more alert and responsive to the next stimulus. The sea slug, Aplysia, a model organism among scientists interested in the neuronal basis of behavior, exhibits sensitization. Aplysia withdraws its gills in response to a touch on the siphon, the tube through which it draws water over its gills. Interestingly, if the animal is given a weak electric shock first, its response to a touch on its siphon is much more rapid, suggesting that the shock has made the slug more sensitive to later stimuli.