Noxious Stimulus

A noxious stimulus is an aversive thing or event; it may be chemical, thermal, or mechanical which is actually or potentially damaging. Noxious stimuli activate pain receptors. For instance, a very hot object (like a burner on an oven) is a noxious stimulus which elicits an aversive response; this is the reason why we do not like to touch very hot objects. Likewise homeowners might put bad-tasting substances on plants to ward off deer, or a parent putting a bad-tasting substance on a child's thumb to keep him or her from sucking on it.