Dog

Although dogs have been the subject of a great deal of behaviorist psychology (e.g. Pavlov's dog), they do not enter the world with a psychological "blank slate". Rather, dog behavior is affected by genetic factors as well as environmental factors. Domestic dogs exhibit a number of behaviors and predispositions that were inherited from wolves. The Gray Wolf is a social animal that has evolved a sophisticated means of communication and social structure. The domestic dog has inherited some of these predispositions, but many of the salient characteristics in dog behavior have been largely shaped by selective breeding by humans. Thus some of these characteristics, such as the dog's highly developed social cognition, are found only in primitive forms in grey wolves.
The existence and nature of personality traits in dogs have been studied (15329 dogs of 164 different breeds) and five consistent and stable "narrow traits" identified, described as playfulness, curiosity/fearlessness, chase-proneness, sociability and aggressiveness. A further higher order axis for shyness–boldness was also identified.