Ambidexterity

Ambidexterity is a condition in which people are adept at using their right and left hands while accomplishing everyday tasks. There are many people that can use their nondominant hand almost as well as their dominant one, but people who can use both hands with equal skill are rare. Ambidexterity is found in one out of every one hundred people, or 1 percent of the population. There is little information about why some people are ambidextrous. It is thought to occur because of differences in the way the brain functions. There are various types of ambidexterity. People who can use both hands but do not have a dominant hand have a form of ambidexterity known as ambisinistral. People can practice and train themselves to become ambisinistral. In fact, many athletes, especially basketball players and boxers, train themselves to be able to use both hands.

Brief History

Although left-handedness and ambidexterity are rare, historians say that people have been using their left hands along with their right hands since as long as humans have existed. Evidence from Kenya shows that several 500,000-year-old stone tools made by prehuman ancestors were created using the left hand.

Even though left-handedness and ambidexterity have been around since the beginning of time, the state of being left-handed or ambidextrous has not always been accepted by society. In medieval Europe, people who were left-handed often used their right hands because left-handedness was associated with the devil. By the fifteenth and sixteenth centuries, left-handedness was enough proof to claim that someone was a witch and could lead to denouncement and death. Because of the stigma associated with left-handedness, people who were left-handed made sure to hide it. People continued to try to suppress left-handedness into the eighteenth and nineteenth centuries, even in more liberal societies like North America and Western Europe. At schools, teachers would hit students on the hands if they caught their pupils writing with their left hands.

Once scientists began to understand that handedness was influenced by the lateralization of the brain, left-handedness started to become less stigmatized. Eventually, people even began to argue that using the left hand to write or perform other activities could be beneficial. People soon began promoting ambidexterity. One such person was English propagandist and teacher John Jackson, who formed the Ambidextral Culture Society in the early twentieth century. Jackson believed that humanity would benefit if everyone learned to use both hands because people would be able to accomplish more.

Still, even in the twenty-first century, parents and teachers will sometimes try to help left-handed children use the right hand because they want to make the students' lives easier. Many products— including scissors, can openers, and even desks—are usually designed to accommodate right-handed people.

Overview

Handedness is attributed to lateralization, which is the structural and functional differences between the right and left hemispheres of the brain. Many operations—such as memory, language, and emotional processing—are specific to one side of the brain. For example, in right-handed people, language is processed in the left hemisphere of the brain. A common myth that has persisted for years is that left-handed people all use the right side of their brain to process language and perform other operations due to lateralization. However, this is not necessarily true. Most left-handed people, about 70 percent, use the left hemisphere to process language as well. Although there is less data on other operations, some experts believe there is little obvious difference in lateralization of other functions—such as face perception and attention—in left-handed people.

Hand preference begins to develop prior to birth. It becomes very noticeable in early childhood and tends to be consistent throughout adulthood. Experts believe that more than forty genes help to contribute to handedness. It is also believed that living environment and chance play a part in handedness as well.

Although ambidexterity may have benefits, recent studies have found that ambidextrous people are more likely to have mental health issues, experience difficulty in school, and have attention deficit hyperactivity disorder (ADHD). A 2010 study that looked at eight thousand Finish children, eighty-seven of whom were mixed-handed, found that the mixed handed seven- and eight-year-old children were twice as likely as the right-handed children were to have trouble with language, and they were more likely to perform poorly in school. By the time the children were fifteen or sixteen, the mixed-handed children were at twice the risk of being diagnosed with ADHD.

Another study found that people who were mixed-handed were more easily influenced emotionally than those who were right-handed. The study attempted to change the moods of right-handed and mix-handed people by asking them to think happy, sad, or anxious thoughts while listening to various kinds of classical music. The study found that the mixed-handed people reported that they had more negative feelings, suggesting that their environment more easily influenced their moods. The right-handed people proved to be less open to suggestion.

Ambidextrous people are also at a higher risk for schizophrenia. The gene that contributes to left-handedness, LRRTM1, also increases the risk for schizophrenia. Because of this, schizophrenic people are far more likely to be left-handed or ambidextrous.

Another brain condition that is related to ambidexterity is synesthesia. This perceptional phenomenon leads people to experience some events with two or more senses simultaneously. For example, some people with synesthesia can "hear" colors, feel physical sensations that other people are feeling, or associate numbers and letters with personalities. A person with synesthesia is more likely to be left-handed or ambidextrous than the average person is.

Despite evidence suggesting that there are various disadvantages to being ambidextrous, including some potential cognitive and mental health issues, some people actively train themselves to try to be able to use their right and left hands interchangeably. This is often seen in sports, especially in baseball, where players will train to bat both left-handed and right-handed. This is called switch hitting, and it can provide an advantage when facing various pitchers. People in other fields, such as business and artistic pursuits, have also attempted to become ambidextrous in an effort to try to "activate" both sides of the brain or increase creativity. However, there is little scientific evidence to support the idea that ambidexterity improves brain function or creativity.

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