Animal personality is defined as differences in behavior between individuals within a certain group or population that are consistent across time and context. Recently, it has been proposed that animal personality can be used as a framework to develop innovative techniques in animal welfare. Nonetheless, identifying animal personality in practice can be time- and resource-consuming, making such implementation less feasible in a commercial setting. Behavioral laterality is the preference for an animal to use one side of the body respect to another to interact or respond to stimuli in the environment. In many species, it has been found that emotions are processed differently by the two hemispheres, and that individuals with different personality process emotional behavior differently. This suggests that individual differences in laterality and personality should covary. To test the robustness of such correlation, we manipulated the environment during development to examine the effects on both laterality and personality, as well as their covariation. More precisely, it is known that perceived predation and conspecifics in the early environment can influence the development of both laterality and personality. If emotional reactions are lateralized in sticklebacks, we expect personality scores to covary with laterality, regardless of the treatment experienced by the individual.
Newly hatched Threespined Sticklebacks were split in 4 treatment groups in a 2v2 design, manipulating predator exposure and social environment during the first 3 months of development. Consequently, they have been tested twice for laterality and boldness. Compared to control individuals, those who experienced predation threat during development showed a stronger lateralized behavior, while those who experienced a richer social environment showed a bolder behavior. Interestingly, boldness and laterality covaried regardless of the treatment, even though such relationship was evident only in the second trial. Such result shows how laterality, a relatively easy to test behavioral measure, has potential to be used as a proxy of personality, more specifically boldness; more research is needed to understand the effect of context on such relationship, which is possibly related to the exposure of the individuals to the same testing environment, eliciting different parts of the brain in reaction to the difference in familiarity.
Paolo Panizzon, Jakob Gismann, Bernd Riedstra, Marion Nicolaus, Culum Brown, Ton Groothuis. Effects of early predation and social cues on the relationship between laterality and personality. Behavioral Ecology, 35, 3. https://doi.org/10.1093/beheco/arae012