Nearly all Americans (87%) are right-handed, while only 13% are left-handed.
Researchers have been studying this difference and conducting studies to see what it may mean for some time, but results have been conflicting.
It now seems that whether a person is right- or left-handed is not important when it comes to memory.
What is important is the degree to which a person is right or left handed. If you use your non-dominant hand at least some of the time, you may find your memory will benefit as a result.
The Edinburgh Handedness Inventory
Some people use their dominant hand almost exclusively for everyday tasks while others use their less dominant hand part of the time. 55% of Americans are considered to be strongly right-handed. They almost never use their left hand. From one to three percent are strongly left handed.
A score has been devised according to the degree to which a person uses one hand or the other. It’s called the Edinburgh Handedness Inventory.
Pure left- or right-handedness scores 100. On average, people score 80. A score below 80 is called inconsistent handedness (ICH). It means that at least one in ten activities is performed with the non-dominant hand. A score above 80 is termed consistent handedness (CH).
CH has been found to be more prevalent among right-handers and women. Left-handers are largely ICH.
Now where all this becomes interesting is the effect handedness has on the brain.
Inconsistent Handers Have Bigger Brains
The corpus callosum connects both sides of the brain and facilitates communication between them. People who are ICH have a larger corpus callosum and increased activation of the right hemisphere. This in turn leads to a better episodic memory.
This is the kind of memory involved with learning, storing, and retrieving information — the ability to describe the details of a recent vacation, for instance.
A number of studies show people with ICH have better recall of words and paragraphs, events from their own life, early childhood memories, everyday memories, dream recall and memory for faces.
This has also been shown to extend beyond the lab into real life, where ICH people report fewer memory problems, particularly those involving conversations and conducting everyday tasks. This is true whether they are left- or right-handed. The relevant trait is whether they make extensive use of both hands.
Connectivity between both hemispheres of the brain is also concerned with the capacity to update beliefs. This is considered to be a broad example of our ability to be flexible in our thinking.
Studies have shown that ICH people are more likely to be open to persuasion and are better at taking other people’s perspectives. People who are CH (consistent handed) are more resistant to updating beliefs and are less likely to alter their existing viewpoint.
Perhaps also relevant, people who switch back and forth between both hands are less likely to suffer from rumination or other eating disorders, and less likely to suffer from dysmorphia — a distorted view about the way they look.
Form New Neural Pathways with Neurobics
If you are strongly left- or right-handed, there’s a very simple way to improve your episodic memory and increase cognitive flexibility.
And that is to practice neurobics. These are brain exercises that involve unexpected stimuli.
One of the simplest exercises to strengthen connectivity between both hemispheres of the brain is to use your non-dominant hand more often by incorporating it into everyday life.
This might include eating, stirring drinks, writing, texting, drawing, dialing phone numbers, brushing teeth, opening doors and hoovering. Virtually anything that’s safe to do will help. Do this consistently over time and you should notice a difference.
Dr. P. Murali Doraiswarmy, head of biological psychiatry at Duke University Medical Center, says of these activities: “It’s like having more cell towers in your brain to send messages along. The more cell towers you have, the fewer missed calls.”