I would compare it to learning an instrument or playing a sport that is unfamiliar to you. The reason why there are cognitive benefits is because of the plasticity of the brain. If you can imagine that the brain is a very large urban city, the roads, buildings, and traffic organization is not stable. It changes quite frequently and rerouting as well as remodeling and renovation are a common part of city life. Your brain (especially at younger ages but not limited to) is especially prone to remapping it's neural connections when new tasks are done. When one learns to play some type of instrument such as a guitar or violin, studies show that after learning for a substantial period of time (studies are done before and after which look at cortical areas that are associated with parts of the body)there is a significant increase in the amount of cortical area dedicated to it.
Often the homunculus is used to explain the conept of body mapping:
This is a general image which cortical areas are associated with which body parts. It is a logical correlation that due to the plasticity, the increased amount of cortical dedication to an area would allow for a increase in function.
So back to the question, the continued use of the non dominant will strengthen neural connections resulting in possible expanded somatosensory senses, increased reflexiveness, and possible additional connections in the brain that weren't there before. This is all speculation, but some neuroscientists and psychologists would attribute the additional connections to possible increased cognitive abilities. In psychology it is typical to associate certain areas of the brain such as the pre-frontal cortex with planning the temporal lobe with hearing etc. thus with strengthened connections and changes in wiring this could lead to changed cognitive patterns and perhaps even changes in behavior. Now of course take this with a grain of salt, don't expect to increase your IQ score significantly simply from using your non dominant hand to brush your teeth. Much of neuroscience is still up in the air, and many of the underlying theories are more or less postulates or strongly suggested ideas by prominent neuroscientists. But in short, yes use your non-dominant hand to do tasks you typically don't, because it has cognitive benefits and it often gives you a unique advantage over others.
Thanks for sharing your thoughts about this topic. Did I get that image right that it would be useful to use body parts with a low correlation?
Yes. Using your non dominant hand or leg results in increased connectivity to the cortical areas corresponding to those limbs.
Hi! I am a robot. I just upvoted you! I found similar content that readers might be interested in:
https://www.quora.com/Are-there-any-cognitive-benefits-you-get-from-learning-how-to-use-your-non-dominant-hand-to-brush-your-teeth-and-to-doing-other-things