8.9—Habituation

Habituation occurs when repeated harmless stimulation produces a smaller response. The animal saves energy because fewer calcium ions enter the presynaptic neurone, less neurotransmitter is released and the postsynaptic cell is less likely to reach threshold.

A snail may take less time to re-emerge after repeated gentle touches. If the sound or touch becomes stronger, the response can return because the stimulus is no longer identical.

The change is in synaptic transmission, not a loss of all sensory ability. The animal can still respond when the stimulus becomes relevant.

Habituation is not fatigue, permanent damage or forgetting every similar stimulus. Control stimulus intensity and use a consistent endpoint when measuring it.