Personality in animals
However, there is recent consensus in the literature for a broad definition that describes animal personality as individual differences in behaviour that are consistent across time and ecological context.
[2] Here, consistency refers to the repeatability of behavioural differences between individuals and not a trait that presents itself the same way in varying environments.
[7] Recent studies have focused on its proximate causation and the ecological and evolutionary significance of personality in animals.
Concepts such as personal objects, identity, attitudes and life stories are not considered relevant in animals.
Similarly, any approach that requires the subject to explain motives, beliefs or feelings is not applicable to the study of animal behaviour.
For example, studies in animal personality often examine traits such as aggressiveness, avoidance of novelty, boldness, exploration and sociality.
The descriptive language used by comparative psychologists in the late nineteenth century often attributed disposition and behavioural tendencies to individual animals in their studies.
In his seminal studies on conditional reflexes, he categorized the behaviour of dogs as Excitable, Lively, Quiet or Inhibited.
The Excitable type, for example, showed signs of strong excitatory conditioning, but a limited ability for the acquisition of inhibitory connections.
Ecologists began to recognize the importance of individual differences in behaviour near the end of the twentieth century.
Repeatability estimates are one of the most widely used statistical tools that can quantify consistent individual differences in behaviour.
[6] The 5 categories for the five factor model for personality are openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism.
[16] Chimpanzees are also the only non-human species shown to demonstrate a hierarchical structure of personality, with two dimensions of affect corresponding to negative and positive emotionality, and a third dimension of disinhibition (vs. constraint), which is thought to comprise a regulatory system that is known to play a role in the perception and interpretation of incoming stimuli.
[clarification needed][17] Neuroticism, agreeableness and extraversion are the most commonly found personality traits among measured animals.
For example, chimpanzees show emotional stability, agreeableness and surgency,[18] audiovisual reactivity, affect-extraversion,[19] excitability-agitation, aggression, affinity and social play.
[20] Some behaviors are correlated into a set of personality traits that remain constant throughout different situations and contexts.
[21] In zebrafish (Danio rerio), Proactive and Reactive personalities express different thermal preferences and general activity within the temperature gradient.
Proactive fish (more aggressive, bold risk-takers, prone to routine formation) have a preference for higher temperature environments.
Also, behavioural traits are more dynamic which may allow an animal to adapt more quickly which, in turn, can speed up the rate of evolution.
[8] Similarly, zebrafish have been used as a neurobehavioral model species for studying personality using the trait approach in non-human animals.
Boldness changes were found to relate to social interactions with nest mates, indicating that individual personality is more plastic in groups.
For example, temperament, behavioral syndrome, disposition and animal personality have been used interchangeably by some while others maintain that each term has a unique meaning.
