The left brain vs. right brain myth - Elizabeth Waters

Summary

The video script dispels the myth of the brain being divided into a logical left and creative right hemisphere. It explains that while the brain does have distinct left and right sides controlling different body functions, such as movement and sight, there's no scientific evidence supporting the idea that one side governs logic and the other creativity. Historical misconceptions arose from 19th-century neurologists' findings on language localization in the left hemisphere. Modern research shows that both hemispheres contribute to a range of cognitive functions, and individual differences in logic and creativity are not determined by brain lateralization.

Takeaways

• 🧠 The human brain is visibly split into left and right sides, but the idea that the left controls logic and the right creativity is a myth.
• 🤔 The brain's left and right sides do control different body functions, such as movement and sight, but this doesn't extend to logic and creativity.
• 👀 The visual system is complex, with each eye having a left and right visual field, and these fields are sent to opposite sides of the brain.
• 🦎 The theory of quicker reflexes due to the left-right structure of the brain might have originated with the development of complex nervous systems in animals.
• 🏥 The misconception of a logical left hemisphere and an emotional right hemisphere began in the mid-1800s with neurologists Broca and Wernicke's findings on language and brain damage.
• 📚 Author Robert Louis Stevenson popularized the idea of a logical left hemisphere and an emotional right hemisphere through his characters Dr. Jekyll and Mr. Hyde.
• 🧬 Patients missing a hemisphere or with separated hemispheres showed a complete range of behaviors, indicating that both logic and creativity are not confined to one side of the brain.
• 🧐 Later research showed that language is more localized to the left side of the brain, and attention to the right, but this doesn't suggest a person has a dominant side for these functions.
• 🤹‍♂️ Creativity and logic are not at odds; they often require each other, and both are the result of the whole brain functioning as one.
• 🧬 There is no scientific evidence to support the idea of individuals having dominant brain hemispheres or a split between logic and creativity based on brain sides.

Q & A

What is the myth about the brain's left and right sides?

The myth is that the left side of the brain controls logic, while the right side controls creativity. This idea is unsupported by scientific evidence.

How is the brain's structure divided?

The brain is visibly split into a left and right side, with the outer layer, or the cortex, being the most apparent. Internal regions like the striatum, hypothalamus, thalamus, and brain stem also have left and right sides.

What functions do the left and right sides of the brain control?

The left and right sides of the brain control different body functions such as movement and sight. The right side controls the motion of the left arm and leg, and the visual system processes visual fields from each eye to the corresponding side of the brain.

What is one theory as to why the brain has a left-right structure for vision and movement control?

One theory is that this structure began soon after animals developed more complex nervous systems, providing a survival advantage of quicker reflexes, such as escaping to the right when a predator is seen on the left.

When did the misconception about the brain's left-right split begin?

The misconception began in the mid-1800s when neurologists Broca and Wernicke examined patients with communication problems due to brain injuries, leading to the suggestion that language is controlled by the left side of the brain.

How did the idea of a logical left hemisphere and an emotional right hemisphere become popular?

The idea became popular after author Robert Louis Stevenson introduced it through his characters Dr. Jekyll and Mr. Hyde, representing a logical left hemisphere and an emotional right hemisphere.

What did doctors and scientists find when examining patients who were missing a hemisphere or had their hemispheres separated?

These patients showed a complete range of behaviors, both logical and creative, indicating that the brain functions as a whole rather than being strictly divided into logical and creative sides.

How does the brain's activity differ for language and attention?

Language is more localized to the left side of the brain, while attention is more localized to the right side. However, this does not mean one side is dominant for all individuals.

Is there evidence to suggest individuals have dominant sides of the brain?

No, there isn't any evidence to suggest that individuals have dominant sides of the brain, nor is there evidence to support the idea of a left-right split between logic and creativity.

How are logic and creativity related in the brain?

Logic and creativity are not at odds with each other. Solving complex math problems requires creative thinking, and many works of art have intricate logical frameworks, indicating that both logic and creativity are often the result of the whole brain functioning as one.

Outlines

00:00

🧠 The Myth of Left vs. Right Brain Dominance

The paragraph debunks the popular myth that the left side of the brain controls logic while the right side controls creativity. It explains that while the brain does have distinct left and right sides, each controlling different body functions like movement and sight, there is no scientific evidence supporting the idea of a left-right split in cognitive functions such as logic and creativity. The paragraph also discusses the historical origins of this misconception, which began in the mid-1800s with Broca and Wernicke's findings on language localization in the left hemisphere. It clarifies that later studies showed no evidence for individuals having dominant brain sides or for a dichotomy between logic and creativity, emphasizing that both cognitive functions are the result of whole-brain activity.

Keywords

💡Cortex

The cortex is the outer layer of the brain, responsible for higher cognitive functions such as thought, action, and consciousness. In the video, it is mentioned as part of the brain's left and right sides, highlighting the misconception that each side controls different aspects of human cognition, such as logic and creativity.

💡Striatum

The striatum is an internal region of the brain involved in the control of voluntary motor functions and reward-based learning. The video notes that while it appears continuous, it too has left and right sides, emphasizing the complexity of brain organization beyond simple left-right distinctions.

💡Hypothalamus

The hypothalamus is a small region at the base of the brain that links the nervous system to the endocrine system via the pituitary gland. It plays a critical role in regulating body temperature, hunger, thirst, sleep, and other homeostatic processes. The video uses it as an example of the brain's bilateral organization.

💡Thalamus

The thalamus is a pair of ovoid bodies situated above the brainstem which relays sensory and motor signals to the cerebral cortex. It is mentioned in the video as another internal region that, despite appearing continuous, is organized into left and right sides.

💡Brain Stem

The brain stem is a part of the brain that connects to the spinal cord and is responsible for many automatic functions necessary for life, such as breathing and heart rate. The video includes it in the discussion of brain regions that are organized into left and right sides.

💡Visual Fields

The visual fields refer to the entire area that can be seen at one time by the human eye. The video explains the complex interaction of visual fields with the brain, noting that the left visual fields from both eyes are processed by the right side of the brain and vice versa.

💡Survival Advantage

Survival advantage refers to traits or behaviors that increase an organism's chances of survival and reproduction. The video suggests that the brain's left-right structure may have evolved due to its survival advantage by enabling quicker reflexes, such as escaping to the right when a predator is seen on the left.

💡Broca's Area

Broca's area is a region in the brain's left hemisphere that is involved in speech production. The video discusses how Broca's findings, along with those of Wernicke, led to the popular but oversimplified idea that the left side of the brain controls language and logic.

💡Hemispherectomy

Hemispherectomy is a surgical procedure in which one of the brain's hemispheres is removed, usually to treat severe epilepsy. The video uses this as an example to counter the myth of brain lateralization, showing that patients who have undergone this procedure still exhibit a range of logical and creative behaviors.

💡Cognitive Functions

Cognitive functions refer to mental actions or processes such as thinking, learning, memory, and perception. The video clarifies that cognitive functions like logic and creativity are not solely controlled by one side of the brain, challenging the myth of a left-brain/right-brain dichotomy.

💡Whole Brain Functioning

Whole brain functioning implies that both hemispheres of the brain work together to perform complex tasks. The video concludes with the idea that creativity and logic are not at odds but are the result of the entire brain working in unison.

Highlights

The human brain's left and right sides are a pervasive myth for logic and creativity control.

The brain's left and right sides do control different body functions such as movement and sight.

The brain's right side controls the motion of the left arm and leg and vice versa.

Each eye has a left and right visual field, contributing to a complete image of the world.

The reason for the brain's left-right structure and its crossing over is not fully understood, but it might offer survival advantages.

The misconception of brain hemispheres controlling logic and creativity began in the mid-1800s with neurologists Broca and Wernicke.

Robert Louis Stevenson popularized the idea of a logical left hemisphere and an emotional right hemisphere.

Patients missing a hemisphere or with separated hemispheres showed a range of logical and creative behaviors.

Later research found that language is more localized to the left brain and attention to the right.

There is no evidence to suggest individuals have dominant brain hemispheres for logic and creativity.

Logic and creativity are not at odds; they often require each other for complex tasks.

Almost every act of creativity and logic is a result of the whole brain functioning as one.

The brain's internal regions like the striatum, hypothalamus, thalamus, and brain stem also have left and right sides.

The left and right visual fields are processed differently in the brain, contributing to a complete visual perception.

The idea of distinct brain hemispheres for logic and creativity was debunked by examining patients with hemisphere deficiencies.

The brain's functions are not strictly divided between the left and right hemispheres; they vary by system and person.

The brain's left-right structure is crucial for movement and sight, but its extension to logic and creativity is a myth.

Transcripts

Behold the human brain,

it's lumpy landscape visibly split into a left and right side.

This structure has inspired one of the most pervasive ideas about the brain,

that the left side controls logic

and the right, creativity.

And yet, this is a myth unsupported by scientific evidence.

So how did this misleading idea come about,

and what does it get wrong?

It's true that the brain has a right and a left side.

This is most apparent with the outer layer, or the cortex.

Internal regions, like the striatum,

hypothalamus,

thalamus,

and brain stem

appear to be made from continuous tissue,

but in fact, they're also organized with left and right sides.

The left and the right sides of the brain do control different body functions,

such as movement and sight.

The brain's right side controls the motion of the left arm and leg and vice versa.

The visual system is even more complex.

Each eye has a left and right visual field.

Both left visual fields are sent to the right side of the brain,

and both right fields are sent to the left side.

So the brain uses both sides to make a complete image of the world.

Scientists don't know for sure why we have that crossing over.

One theory is it began soon after animals developed more complex nervous systems

because it gave the survival advantage of quicker reflexes.

If an animal sees a predator coming from its left side,

it's best off escaping to the right.

So we can say that vision and movement control are two systems

that rely on this left-right structure,

but problems arise when we over-extend that idea to logic and creativity.

This misconception began in the mid-1800s

when two neurologists, Broca and Wernicke,

examined patients who had problems communicating due to injuries.

The researchers found damage to the patients' left temporal lobes,

so they suggested that language is controlled by the left side of the brain.

That captured the popular imagination.

Author Robert Louis Stevenson

then introduced the idea of a logical left hemisphere

competing with an emotional right hemisphere

represented by his characters Dr. Jekyll and Mr. Hyde.

But this idea didn't hold up when doctors and scientists

examined patients who were missing a hemisphere

or had their two hemispheres separated.

These patients showed a complete range of behaviors,

both logical and creative.

Later research showed that one side of the brain is more active than the other

for some functions.

Language is more localized to the left

and attention to the right.

So one side of the brain may do more work,

but this varies by system rather than by person.

There isn't any evidence to suggest

that individuals have dominant sides of the brain,

or to support the idea of a left-right split

between logic and creativity.

Some people may be particularly logical or creative,

but that has nothing to do with the sides of their brains.

And even the idea of logic and creativity being at odds with each other

doesn't hold up well.

Solving complex math problems requires inspired creativity

and many vibrant works of art have intricate logical frameworks.

Almost every feat of creativity and logic

carries the mark of the whole brain functioning as one.