It was always assumed that only humans have personalities. However, personalities have recently been discovered in animals ranging from spiders to apes. Animals labelled as “friends” and, in some circumstances, entire social groups exhibit similar psychological qualities.
Personality assessments and a battery of learning tests with common marmosets – tiny monkeys from South America – were undertaken by a group of cognitive and behavioral biologists from the University of Vienna, who discovered that a relationship, entangled with family group membership, occurs in these monkeys as well. The findings of the study were recently published in the journal Scientific Reports.
Personalities have been associated with human qualities, as well as cognitive abilities such as academic or professional achievements. It has been suggested that animals who are more explorative and/or bold learn quicker.
Vedrana Šlipogor and colleagues from the University of Vienna investigated if such a relationship exists in common marmosets. They also checked to what degree this is connected to family group membership in the new study.
The monkeys’ personalities were assessed by evaluating their reactions to unfamiliar objects, different types of food, and the amount of time it took them to approach a toy snake. They discovered that some monkeys were quite explorative and daring, while others attempted to avoid the stimuli and keep a distance using similar activities.
The monkeys’ performance in various learning tasks was evaluated by the researchers. For example, the monkeys were taught to grasp a ‘target’ training stick, stand on a weighing scale while holding a ‘target’ stick, and reach the farthest point in the test set-up in the simplest learning tasks. The monkeys’ learning abilities were also put to the test in more difficult activities, such as forming associations between items of the same size but different colours and shapes, or between objects with similar characteristics but different sizes.
In general, female marmosets learned faster than the males. Marmosets learnt well across a variety of cognitive tests. The authors’ findings confirmed the speed-accuracy trade-off framework: learning speed in these monkeys was predicted by personality (attribute Boldness-Shyness). Yet, social considerations played a role: these monkeys’ participation in family groups, especially when combined with their bold-shy characteristics, tended to influence how they learned across tasks.
The effects of belonging to specific family groupings on learning speed might be owing to a shared social context, prior common experiences, or heredity. From an evolutionary perspective, it is possible that both personality and social environment influence learning since braver people are more likely to act in new situations and/or new or demanding physical and social surroundings.
“It seems that both certain personality traits, as well as social environment, have an effect on individual variation in cognition in marmoset monkeys”, Šlipogor says. “In our future studies, we aim to see whether these findings hold with other tasks that are more demanding for the monkeys, and whether this effect can be found in other social animals with similar socio-ecological features.”