Sensory generalization and learning about novel colours by poultry chicks.

In nature animals constantly encounter novel stimuli and need to generalize from known stimuli. The animal may then learn about the novel stimulus. Hull (1947) suggested that as they learn animals distinguish knowledge based on direct experience from inference by generalization and in support of this view suggested that if a subject is directly trained to a stimulus subsequent extinction of responses is slower than when the response is based on generalization.