Some neuroscientists believe that someone’s hand preference tells us something about the way that a person’s brain is organised. It is common knowledge that the left side of the brain controls the right side of the body and vice versa. There is also research that showcases that the emotional responses on the two sides of the brain are different. Some of the data suggests that in humans the left brain is associated with positive feelings, like love, a sense of attachment, a feeling of safety and calm. Whereas the right side of the brain in humans can portray negative behaviors, like fleeing, and emotions like fear and aggression are more common.

In some further research, it has been argued that because the left side of the brain controls the more dominant side of a right-handers’ body, that the more positively feeling half of the brain also comes to dominate their emotions, while for left-handers it is their more negative-feeling right side of the brain which has more influence on their emotions. The results of these types of studies are quite mixed, however, they’re higher rates of left-handers in groups of people with depression and anxiety, and is also prominent in groups of criminals.

Some animal research also suggests that birds, frogs, monkeys and dogs have similarly organised brains as we’ve just discussed above. For example, a dog wags its tail left or right depending on whether the situation is positive or negative. Mostly, a dog wags right for positive and left for negative, when the emotions associated with the right or left side of the brain are activated.

As dogs do have paw preferences which is similar to hand preferences in humans, a team of researchers from the University of Adelaide conducted a study with 73 pet dogs to see if there were differences in the emotional responses of right and left pawed dogs. 37% of the dogs tested showing no paw preference at all. Of the remaining 63%, 34% were left pawed and 29% were right pawed.

Dr. Schneider, leading the study, summarises his results to the Canine Behavioral Assessment and Research Questionnaire (C-BARQ) as follows, “I reported a statistically significant relationship between stranger directed aggression and the presence of a paw preference. Dogs without a paw preference demonstrated lower aggression scores. When I looked more closely at the dogs with a paw preference, it appeared that it was those dogs with a preference for the left paw that were driving this relationship.”

These results are consistent with the kind of findings that researchers find in left-handed humans, with reports that they are more likely to react with negative emotions and even aggression than their right-handed counterparts. Of course in both dogs and humans there are many other factors which determine the likelihood of aggressive responses, including age, sex, personal history, health, and genetic factors. However looking at these results prompted Dr. Schneider to say, “The take-away message for me is that there appears to be more similarities between human and animal brains than we once thought.”

Data from;  Schneider, L.A., Delfabbro, P.H., & Burns, N.R. (2013) Temperament and lateralization in the domestic dog (Canis familiaris). Journal of Veterinary Behavior: Clinical Applications and Research, 8 (3), 124-134.