If you predominantly use your left hand for daily activities, you are part of a rare population known as a left hander. But, what if you favor one or the other hand depending on the task? What if you can use both your right and left hand equally in everything you do? This is where mixed-dominance and ambidexterity come into play. We spoke with experts who define each of these terms. So, the next time someone asks you if you’re a lefthander, you can confidently give them a clear, concise answer that may even teach them a thing or two about handedness.
How to Assess Left Handedness
You have probably heard someone who is left-handed being referred to as a left hander, lefty, or southpaw (click here to learn more about where the term 'southpaw' originated). An estimated 10.6% of the population (Papadatou-Pastou, M., Ntolka, E., Schmitz, J., Martin, M., Munafò, M. R., Ocklenburg, S., & Paracchini, S. --- 2020. Human handedness: A meta-analysis. Psychological Bulletin, 146(6), 481–524) are fortunate enough to be included in this club. A left hander faces challenges on a daily basis with some of the simplest tasks that most of the world’s population take for granted. This includes young children in school, some of whom are still determining their handedness. If you favor your left hand when writing, cutting, peeling, or opening a can, I’m sure you know what we’re talking about. However, we’re certain that most southpaws would not change it for anything as we embrace our uniqueness and triumph through the little struggles.
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Many people have their own definition as to what they believe makes a left hander, and it can sometimes become quite confusing. Simply put, a lefty is someone who predominantly prefers using their left hand for everyday tasks. Dr. Marietta Papadatou-Pastou is an assistant professor at the National and Kapodistrian University of Athens and is a leading expert in this field.
“I have to say that even experts in the field are confused about what a left hander is,” says Dr. Papadatou-Pastou. “So people would usually assume that it's about which hand they would write with. So I write with my left hand therefore I’m a left hander. But, it's not just handwriting. It's also which hand we use to throw a ball, to hold the toothbrush, or which hand we use to hold a fork. We have preference as well as skill and both of them lie on a continuum from one extreme to the other extreme and we can be anywhere in that continuum.”
Emanuella Correia, an expert in left-hand education and founder of Brazilian-based Canhotopia, says,
“If a person does 70% or more of their routine activities with a left hand, this is considered a left-handed person.”
There are at least two common tests researchers use to determine one’s handedness. They may ask for the participant’s preference in a questionnaire for which hand they use when performing different activities such as writing, throwing, eating, brushing their teeth, etc. If you prefer doing over half of these activities with your left hand, congratulations you are left-handed! However, if you prefer using both hands for different activities, you are likely mixed-handed or maybe even ambidextrous. Dr. Papadatou-Pastou says,
“So, we end up with a score. One can be on a continuum. One can use the same hand for all activities, so they’re strong left handers or strong right handers. Or they can use one hand for some activities, the other hand for other activities so they're mixed-handed. And there are also people who are equally well-skilled with both hands for the same activities, and who are considered to be ambidextrous.”
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In addition, researchers test for performance. This is a more reliable way to determine handedness as they run tests measuring the accuracy and speed for each hand of the participant.
“We also have the notion of relative hand skill,” says Dr. Papadatou-Pastou. “We measure that in different ways. We might ask participants to move pegs like wooden pegs from rows that have holes and then we can time them to see which hand is faster. Or, we might measure their grip strength or ask them to put dots on paper. We then see which one is relatively more skilled.”
The three most common ways to determine handedness in an informal setting is by recognizing which hand someone uses to write, eat, and throw a ball. If they can do at least two of these three tasks with their left, they are most likely a lefthander. Although it may seem like a strange concept for some, a person could be left-handed without writing with their left hand, as long as they perform most of their daily activities with their left hand. However, a “strong lefty” is one who performs all tasks with their left hand.
You likely now see how there is a little more to handedness than just being right or left-handed.
What is Mixed Handedness
Mixed handedness is when you perform some tasks better with your right and other tasks better with your left, as described by Dr. Papadatou-Pastou:
“So, one might be writing with the right hand, but then prefer their left hand, for example, for throwing a ball or maybe closing a lid or maybe striking a match. Mixed handedness cannot be very strictly defined by how many activities and the percentage of those activities which can be done with either hand. But in principle, it means that I use my one hand for some activities and another hand for some other activities.”
Individuals who are truly mixed-handed are said to be about 9.33% of the world’s population (Papadatou-Pastou, M., Ntolka, E., Schmitz, J., Martin, M., Munafò, M. R., Ocklenburg, S., & Paracchini, S. --- 2020. Human handedness: A meta-analysis. Psychological Bulletin, 146(6), 481–524). However, Dr. Papadatou-Pastou cautions that mixed-handedness and ambidexterity are “not something we (the science community in general) have really agreed how to measure. But, these figures are based on what we know at the moment.”
Mixed handedness is quite unique because these individuals display some form of dexterity on both sides since they use different hands for different activities. If you are mixed-handed, you typically have an advantage when training to be “somewhat” ambidextrous since you already possess coordination and motor skills from both sides of your body during certain tasks.
In some sports, being mixed dominant can prove to be a strategic advantage for athletes. Professional basketball player LeBron James signs autographs with his left hand, yet is right-hand dominant when he plays basketball.
“What is surprising in LeBron's case is that it's not the other way around because it's much more likely to see someone who writes with their right hand to use their left or be ambi-lateral in sporting activities,” says Dr. Papadatou-Pastou. “This was actually shown by a recent study on basketball players. And this shift towards the left can give you a tactical advantage in sports, especially sports that involve an opponent like tennis for example. But, also team sports like basketball where we have direct contact amongst players. It's actually interesting to see an interview where he (LeBron James) was asked why he shoots with the right hand although he’s a left hander and he just said that when he was younger and he was watching basketball, he thought it was cooler and this is why he started doing that. So there you go, environmental influence, non-explicit model learning as we call it in science.”
Ambidextrous
The rarest group in handedness is ambidexterity, which includes about only 1% of the population. Ambidextrous people are able to perform any task equally well with either hand. For example, an ambidextrous person can write with ease using their left or right hand, and there isn’t a noticeable difference in quality of the work. However, Dr. Papadatou-Pastou says defining ambidexterity has not been agreed upon by experts.
“I cannot give you a response where everyone will agree on. Some experts might say, ‘I want someone to use both hands for all activities if I'm going to label them as ambidextrous.’ But others might say, ‘I'm only going to look at the writing hand, for example, for this piece of research.’ So, there is not one good answer for this question. It depends on how the researcher defines their participant groups.”
Often, left handers are forced to adapt to a right-hand dominated world. Usually lefties become mixed handed because very few people out there can perform ALL tasks equally well with both hands. Ms. Correia says,
“There’s always been a misconception about what ambidextrous is. For instance, I have friends who write with their right hand, but they do one thing with their left hand and they say, ‘I’m ambidextrous’ and they are very certain of this. Or, sometimes teachers who have been talking to me say, ‘I have children who are ambidextrous.’ What they are seeing is a child who changes their hands while they are writing because they get tired, so they change their hand. That does not make them an ambidextrous person. In fact, we have only one percent of the population who are actually ambidextrous. Why? Because ambidextrous is someone who can do everything with both hands. So, if you have a person who can draw simultaneously with both hands, they can write with both hands, eat with both hands. They can do anything with both hands.”
Research has shown you can train yourself to become ambidextrous; however it is obviously quite difficult. Most end up gaining significant strength in their opposite arm, yet never fully achieve true ambidexterity. So, for those who have a little extra time on their hands (pun not intended) and want to be part of the 1%, maybe start practicing---a lot---if you want to show off your ambidexterity.
Summary
There are several tests to assess left handedness. Depending on the skill, you may prefer using your left or right hand.
If you find your left hand is strongest for most of your daily activities (writing, kitchen, gardening and home improvement tools, cutting with scissors or a knife, etc), then you are likely a strong left hander. When assessing yourself, consider if you use your right hand for any of these activities because you are more or less forced to, for example, a right-handed mouse for your computer.
You may also prefer using different hands for different tasks, in which case you may be mixed-handed with a possible slight preference for left or right.
If you can do everything equally well with both hands, you might very well be part of the estimated 1% of the population who are ambidextrous.