Personality

Human personality is something with which we are all familiar, in that we ‘know it when we see it’. In fact, personality is what distinguishes one individual from another.

Defining personality scientifically, however, is not easy. Psychologists have worked on this problem for a long time and a lot has been written on how to define, classify, and measure human personality traits.

Just like us, other animals differ strikingly in character and temperament. Increasingly it is becoming accepted that personalities are widespread in the animal kingdom and the concept of personality is now being applied to nonhuman animals.

Like people, animals can be described as having personalities because individuals consistently differ from one another in behaviour in such a way that these behaviours can be described as individual traits. These differences should be consistent across time, contexts (when the behaviours occur e.g. feeding, aggression, courtship), situations (the environmental or social condition at a particular time e.g. the high and low predation risk experienced with movement through a habitat) and measures (ways of measuring personality e.g. by behavioural tests, ratings by knowledgeable judges, or observations of naturally occurring behaviour).

Until recently it was thought that there was no particular reason for animals, including humans, to have personalities. However, it is now thought that having consistent individual differences in behaviour could be adaptive   and so personality could have an important effect on evolution, and vice-versa. Interestingly, there is increasing evidence for a strong genetic contribution to personality.

However, personality is not constant and changes throughout an animals’ lifetime. Therefore an area of interest for animal personality researchers is one that mirrors the longstanding ‘nature verses nurture debate’ in studies of human personality. Individuals may also show ‘behavioural plasticity’ which is variation in behaviour between different situations.

One of many models for describing human personality measures differences in five independent dimensions : generally speaking, differences in sociability and assertiveness are called Extraversion; variation in trust and cooperation are grouped as Agreeableness; Conscientious describes differences in discipline, planning, and self-control; variation in curiosity and creativity is captured by Openness; and a dimension called Neuroticism differentiates individuals in terms of anxiety, emotional stability, and stress response. This is referred to as the Five-Factor Model (FFM).

This model has been used as the starting point for several investigations into personality in nonhuman primates and other animals, with some success in 12 different species .

However, approaches to studying personality in different species have to differ according to the species’ behaviour and environment in which it is living. For example, as in humans, one can obtain reliable ratings of chimpanzees and other nonhuman primates on traits such as ‘inventive,’ which is not surprising given the behavioural and genetic similarities between humans and nonhuman primates. On the other hand, trying to assess the ‘inventiveness’ of hermit crabs does not make as much sense. However, hermit crabs hide inside their shells when threatened before re-emerging; the duration of these startle responses can be readily measured and easily studied across situations of high and low predation risk.

Personality differences have now been described in more than 60 species. Animals in which the presence of personalities have so far been claimed include humans and other primates such as chimpanzees, gorillas and orang-utans, dogs, cats, squirrels, birds, fish and octopuses.

OneKind is firmly opposed to any experiments using animals that causes them pain or suffering. Where such experiments increase our understanding of animal sentience, we will report them in the long term interest of all animals. The more scientific evidence we have of the capacities of other animals as sentient creatures the stronger our case for re-evaluating our relationships with them to benefit us all.