Left-brained people are supposed to be logical, analytical, and methodical, while right-brained people are supposed to be creative, disorganized, and artistic. But this left-brain / right-brain theory has been refuted by a large-scale, two-year study by researchers at the University of Utah. In other words, it is untrue that logical people predominantly use the left side of the brain and artistic people predominantly use the right. All people use both halves of the brain. However, the stereotypes associated with being left- or right-brained persist and continue to arouse curiosity.
This comparison explains some myths and facts about the topic and compares what are now only metaphors of left-brained and right-brained personality types.
|Left Brain||Right Brain|
|Functions||Speech and language, logical analysis and reasoning, mathematical computations.||Spatial awareness, intuition, facial recognition, visual imagery, music awareness, art, rhythm.|
|Traits||Linear thinking, sequential processing, logical decision-making, reality-oriented.||Holistic thinking, random processing, intuitive decision-making, non-verbal processing, fantasy-oriented.|
|Perceived personality traits||Analytical, logical, pay attention to detail||Creative, artistic, open-minded.|
|Overall Thinking||Linear, detail-oriented - "details to whole" approach.||Holistic, big-picture oriented - "whole to details" approach.|
|Thought process||Sequential; verbal (process with words).||Random; non-verbal (process with visuals).|
|Problem-solving||Logical - order/pattern perception; emphasis on strategies.||Intuitive - spatial/abstract perception; emphasis on possibilities.|
|Controls muscles on||Right side of the body.||Left side of the body.|
|Strengths||Mathematics, analytics, reading, spelling, writing, sequencing, verbal and written language.||Multi-dimensional thinking, art, music, drawing, athletics, coordination, repairs, remembers faces, places, events.|
|Difficulties||Visualization, spatial/abstract thinking,||Following by sequence, understanding parts, organizing a large body of information, remembering names.|
|When damaged||Trouble speaking or understanding spoken or written words; slow, careful movements; inability to see things on the right side of the body.||Trouble with visual perception (understanding how far or near something is); neglect of left side of the body; inability to see things to the left; poor decision making; impulsiveness; short attention span; slow learning of new things.|
The theory of right brain vs. left brain dominance originates with Nobel Prize winning neurobiologist and neuropsychologist Roger Sperry. Sperry discovered that the left hemisphere of the brain usually functions by processing information in rational, logical, sequential, and overall analytical ways. The right hemisphere tends to recognize relationships, integrate and synthesize information, and arrive at intuitive thoughts.
These findings, while true, serve as the basis for the now-disproved theory that people who are logical, analytical and methodical are left-brain dominant, and those who are creative and artistic are right-brain dominant.
A study conducted at the University of Utah has debunked the myth. Neuroscientists analyzed over 1,000 brain scans from people between the ages of seven and 29. The brain scans did not show any evidence that people use one side of the brain more than the other. Essentially, the brain is interconnected, and the two hemispheres support each other in its processes and functions.
Lateralization of Brain Function
The human brain is split into two distinct cerebral hemispheres connected by the corpus callosum. The hemispheres exhibit strong bilateral symmetry regariding structure as well as function. For instance, structurally, the lateral sulcus generally is longer in the left hemisphere than in the right hemisphere, and functionally, Broca's area and Wernicke's area are located in the left cerebral hemisphere for about 95% of right-handers, but about 70% of left-handers. Neuroscientist and Nobel laureate Roger Sperry has contributed significantly to the research of lateralization and split-brain function.
Brain Process and Functions
The left hemisphere of the brain processes information analytically and sequentially. It focuses on the verbal and is responsible for language. It processes from details into a whole picture. The left hemisphere's functions include order and pattern perception as well as creating strategies. The left hemisphere controls the muscles on the right side of the body.
The right hemisphere of the brain processes information intuitively. It focuses on the visual and is responsible for attention. It processes from the whole picture to details. The right hemisphere's functions include spatial perception and seeing possibilities in situations. The right hemisphere controls the muscles on the left side of the body.
Result of Damage
When people sustain an injury or have a stroke that's localized on one side of the brain, they have specific troubles. When the left hemisphere of the brain is damaged, people have difficulty speaking or understanding words either said or written down. They cannot see things on the right side of the body. It affects motor skills (limb apraxia ) and they often move slowly and carefully.
People with damage to the right hemisphere of the brain often have trouble with visual perception and spatial orientation, for example, getting a sense of how far or near an object is in relation to the body. They often neglect the left side of the body, and they're not able to see things on the left. These people are often impulsive and make poor decisions. They also have a short attention span, and their ability to read, process some elements of language  or learn new things is slowed down.
Application in WW-II
If a specific region of the brain, or even an entire hemisphere, is either injured or destroyed, its functions can sometimes be assumed by a neighboring region in the ipsilateral hemisphere or a corresponding region in the contralateral hemisphere, depending upon the area damaged and the patient's age.
Michael Gazzaniga, neuroscientist and a protégé of Sperry, talks about the specific case of WJ, a WWII veteran and epileptic patient as a result of war injury. He was the first veteran to undergo experimental split-brain surgery, which was successful. To quote Gazzaniga from his interview:
WJ was the first moment of excitement, he made a slow recovery from surgery, he was about 50 when he was operated on so I remember him visiting Caltech, coming up in a wheelchair in a protective helmet and all kinds of gear. Anyway we rolled him in to our testing room and these were really first days so it was very crude, we had the pipes that sent the water to the various labs and everything were open and exposed in the ceiling and so we literally threw a rope over them and hung this screen that you could back-project on, and then using a little gadget we could flash pictures to one side of a fixation point and accordingly, if you know how the visual system is hooked up, if you flashed it to the left of the fixation point that went exclusively to your right hemisphere, and if you flashed it to the right it went exclusively to your left hemisphere. It's just the way we're wired up.
People who are analytical and logical and who pay attention to detail are said to be left-brain dominant, i.e., they use the left side of the brain more than the right side. Basic characteristics of left-brain thinking include logic, analysis, sequencing, linear thinking, mathematics, language, facts, thinking in words, remembering song lyrics and computation. When solving problems, left-brained people tend to break things down and make informed, sensible choices. Typical occupations include being a lawyer, judge, or banker.
People who are creative, artistic and open-minded are said to be right-brain dominant, and the right side of their brain is more dominant. Basic characteristics of right-brain thinking include creativity, imagination, holistic thinking, intuition, arts, rhythm, non-verbal, feelings, visualization, recognizing a tune and daydreaming. When solving problems, right-brained people tend to rely on intuition or a "gut reaction." Typical occupations include politics, acting, and athletics.
- The Laterlaization of Brain Function: It is true that the two lateral halves of the brain have neurons or receptors for different functions. There is evidence to show that some cognitive functions like speech and language are linked with the left hemisphere, while face recognition are in the right hemisphere. However, even for the specific functions to be executed, humans use the entire brain.
- There exist personality types who are predominantly more analytical than artistic.
- Everyone uses their brain holistically, regardless of whether they're analytical or creative.
- It is possible to be analytical/logical as well as artistic/creative and many people are.
What's Not True
- The fact that analytical people are governed by the left side of their brain or creative people are governed by the right side of their brain.
- Analytical people cannot be creative (or the other way round) because only one part of their brain is dominant.
Strengths and Difficulties
Left-brained people are supposed to be good at mathematics, reading, spelling, writing, sequencing and verbal and written language. They may have difficulty with abstract visualization.
Right-brained people are supposed to be good at multi-dimensional thinking, art, music, drawing, athletics, coordination and repairs. They remember faces, places and events. However, right-brained people may have difficulty understanding parts if they can't see the whole. They may also struggle with sequencing, organizing a large body of information and remembering names.
Of course, these are stereotypes and any individual can have strengths and weaknesses from either set. There could also be differences in the way the brain processes various categories of cognitive skills. e.g., both left-brained and right-brained people can be good at spelling but how they do it may be different. Left brains memorize the sequence of each letter in a word; right brains memorize the image of the whole word. You might see right brains raise their finger during spelling questions to draw out the word in mid air in front of their face to mentally visualize that whole word.
- Left Brain vs. Right: It's a Myth, Research Finds - Live Science
- Left Basic Characteristics of Left and Right Brain - UCMAS
- Which Way Do You Spin… Left Brain or Right Brain? - Lateral Action
- The rehabilitation of limb apraxia: a study in left-brain-damaged patients. - NIH.gov
- Strokes in the Left and Right Brain - University of Wisconsin-Madison
- Study Challenges Theory About Left Brain/Right Brain Behavior - HealthDay
- Are you a Right-Brain or Left-Brain Thinker? - University of Alabama (PDF)
- An Evaluation of the Left-Brain vs. Right-Brain Hypothesis with Resting State Functional Connectivity MRI - Plos One
- How an Epilepsy Treatment Shaped Our Understanding of Consciousness - The Atlantic