A neutral stimulusStimulus A change in the environment. If the stimulus has no effect on the animal, it is a neutral stimulus. A stimulus that stands out in the environment, that the animal notices more than other environmental stimuli, is a salient stimulus. A stimulus that causes a change of state in the animal, that causes him to perform a specific behavior, for example, is a discriminative stimulus. paired with a primary reinforcerPrimary reinforcer A reinforcer that the animal is born needing. Food, water, and sex are primary reinforcers. until the neutral stimulus takes on the reinforcing properties of the primary. A clickerClicker A toy noisemaker. Animal trainers make use of the clicker as an event marker to mark a desired response. The sound of the clicker is an excellent marker because it is unique, quick, and consistent., after being repeatedly associated with a food treat or other reinforcerReinforcer Anything a animal will work to obtain. , becomes a conditioned reinforcerSecondary reinforcer A conditioned reinforcer. A reinforcer the animal is not born needing. Secondary reinforcers may be as, or even more, powerful than a primary reinforcer. Synonyms: conditioned reinforcer.