Dishabituation

Dishabituation is a phenomenon in psychology and neuroscience in which a response that has diminished through habituation recovers after the presentation of a new, salient, or otherwise novel stimulus, or after a change in context. It reflects a temporary re-engagement of the sensory or motor response to the original stimulus, rather than the creation of a new learning.

In classic experiments, dishabituation is observed when a subject repeatedly exposed to a harmless stimulus shows a reduced reaction over time, but the reaction returns to baseline levels after a strong or novel stimulus is introduced. For example, in animal studies of the gill-withdrawal reflex, a strong tail shock may cause the reflex to reappear when the original tactile stimulus is presented again. In human psychophysiology, a startle or orienting response to a tone may re-emerge after a distracting or novel stimulus is introduced.

Dishabituation is distinct from sensitization. Sensitization is a general increase in responsiveness to a range of stimuli, usually due to a noxious or arousing event, whereas dishabituation specifically involves the reemergence of a response to a previously habituated stimulus due to a change that temporarily resets the habituation process. The effect is typically short-lived, with the original stimulus remaining subject to subsequent habituation upon continued exposure.

The phenomenon provides insight into attention, novelty detection, and the plasticity of sensory processing. Neural mechanisms are thought to involve interactions among sensory cortices, attention networks, and arousal systems, with contributions from novelty-detection circuits. Dishabituation is widely used in basic research and has implications for understanding sensory processing and certain clinical conditions where habituation and novelty processing may be altered.