Stimulus control

The state in which a behaviour reliably happens in response to a specific cue, and does not happen in the absence of that cue.

A dog who lies down only when asked, rather than offering the behaviour repeatedly hoping to be reinforced, is under stimulus control. A horse who walks forward only when asked, rather than wandering off as soon as the handler stops paying attention, is also under stimulus control. A parrot who steps up only when asked, rather than offering the behaviour every time a hand is near, is under stimulus control.

Stimulus control is one of the markers of well-installed training across species. A behaviour that is reliably present on cue, and reliably absent in the absence of the cue, has been brought under control of the relevant stimulus and is ready to be used in real working contexts.

Achieving stimulus control typically requires both positive reinforcement for the behaviour on cue and either non-reinforcement or negative punishment for the same behaviour off cue. The animal learns that the behaviour is only worthwhile when the cue is present, and stops offering it speculatively.

In practical training, lack of stimulus control often shows up as the animal offering trained behaviours unprompted. A dog who has been shaped to bow on cue but who also offers the bow whenever they hope to be reinforced has the behaviour but not the stimulus control. The fix is to reinforce the behaviour only when it is cued, and to ignore or interrupt it when it is offered without a cue.

Stimulus control is what makes trained behaviours useful in working contexts, where the handler needs to know that the animal will do the behaviour when asked and only when asked.