in psychology, the ability to perceive and respond to differences among stimuli. It is considered a more advanced form of learning than generalization (q.v.), the ability to perceive similarities, although animals can be trained to discriminate as well as to generalize.

Application of discrimination procedures permits description of the sensory acuities of laboratory animals. For example, if a dog's salivation response was to be conditioned to a red light by pairing it with food, while a green light was intermittently presented always without food, the dog would salivate to red light but not to green. It then might be inferred that the dog discriminated between colours. If, however, the brightness of the green light was varied, a brightness would be discovered to which the dog salivated. No amount of additional discrimination training with red and green lights would lead to differential response. The conclusion would be that the dog is colour-blind (which, in reality, dogs are).