Ambidexterity is the capacity to use both the right and left hand with nearly equal skill. This trait is uncommon, with genuine ambidexterity appearing in only about one percent of the population. The term itself comes from the Latin roots ambi (both) and dexter (right), translating to “both right.” In a world structured for right-handed individuals, who make up about 90% of people, ambidexterity stands out as a unique characteristic.
The Ambidextrous Brain
The foundation of handedness is the functional specialization of the brain’s two hemispheres, a concept known as brain lateralization. In most right-handed individuals, the left hemisphere is dominant for fine motor control and language. The brain of an ambidextrous person shows a different pattern of more symmetrical function, suggesting neither hemisphere has established strong dominance for motor tasks.
This neurological symmetry is linked to the corpus callosum, the large bundle of nerve fibers connecting the left and right hemispheres that facilitates communication. Some research suggests that the corpus callosum in less lateralized individuals, including some left-handers and ambidextrous people, may be larger. This could allow for more effective interhemispheric communication and the ability to coordinate skilled movements with either hand.
The degree of lateralization can vary significantly among individuals. For instance, males and strongly right-handed people tend to show a higher degree of brain lateralization compared to females, left-handed individuals, and those who are ambidextrous. This reduced specialization means that cognitive functions are more diffusely distributed across both hemispheres. This distribution is a neurological feature that distinguishes the ambidextrous brain from the more typically lateralized brains of the right-handed majority.
Types of Handedness
Handedness is best understood as a spectrum rather than a set of absolute categories. While most people are right-handed, meaning they are more skillful with their right hand, about 10% of the population is left-handed, showing a preference and greater dexterity with the left hand.
Ambidexterity, the ability to perform tasks equally well with either hand, is often confused with mixed-handedness, but the two are distinct. True ambidexterity is rare and implies equal skill in a range of activities. In contrast, mixed-handedness, or cross-dominance, refers to the tendency to prefer different hands for different tasks. For example, a mixed-handed person might write with their right hand but throw a ball with their left.
The distinction between skill and preference is important. Mixed-handedness is about which hand is chosen for an activity, whereas ambidexterity is about the level of performance with either hand. Determining true ambidexterity requires performance-based tests, such as writing speed and accuracy with each hand, to confirm the skill level is comparable.
Innate Trait or Learned Skill
The question of whether ambidexterity is an inborn trait or an acquired skill is complex, with evidence supporting both. Genetics play a role, as handedness runs in families. Research suggests multiple genes contribute to hand preference, and this genetic predisposition can lead to “natural” ambidexterity, though it is rare.
Environmental factors also contribute significantly, accounting for a large portion of the variance in handedness. Many ambidextrous individuals were originally left-handed but learned to use their right hand due to cultural pressures or the prevalence of right-handed tools and environments. This “trained” ambidexterity is a common pathway to developing skill with the non-dominant hand. For instance, a left-handed person who injures their dominant hand may be forced to become proficient with their right hand out of necessity.
While a person can intentionally train their non-dominant hand to improve its dexterity, achieving true ambidexterity where both hands have equal skill is a difficult undertaking. Most people who train this way still retain a preference for their originally dominant hand. However, consistent practice can create new neural circuits, allowing the brain to adapt and learn new motor skills with the less-favored hand.
Cognitive and Developmental Associations
Scientific inquiry has explored connections between ambidexterity and various cognitive traits, though the findings are often correlational and not causal. Some studies suggest a link between non-right-handedness, including ambidexterity and mixed-handedness, and creativity. This may be particularly true for divergent thinking, which is the ability to generate multiple solutions to a problem.
At the same time, other research has pointed to associations between ambidexterity and certain developmental challenges. Some studies have noted a higher incidence of symptoms related to attention-deficit/hyperactivity disorder (ADHD) in individuals with mixed-handedness. This connection is thought to be related to atypical brain lateralization.
It is important to approach these findings with caution, as the research landscape is complex and sometimes contradictory. For example, while some studies link ADHD symptoms with enhanced creativity, the evidence is not always consistent, particularly when comparing individuals with subclinical traits to those with a clinical diagnosis. The relationship between handedness and brain development remains an active area of scientific investigation.