You get to decide what to believe, so choose wisely.

This is the First Thing You Need to Do to Change Your Life

Patrik Edblad
Feb 14, 2017 · 6 min read

In the 1960’s, cognitive neuroscientists Michael Gazzaniga and Roger Sperry performed research on split-brain patients (1).

These patients had once suffered from extreme and controllable forms of epilepsy.

By disconnecting the two brain halves, it was found that their seizures became less severe (2).

But it also made it impossible for the two hemispheres to communicate with each other.

And this condition gave Gazzaniga and Sperry a unique opportunity to examine the functions of each hemisphere.

Split-Brain Experiments

As the researchers began investigating the split-brain patients, they soon found that no information was transferred between their brain halves.

Unsurprisingly, the left hemisphere had no idea what the right one was doing, and vice versa.

Then, in the early 1980’s, Gazzaniga did one more of his signature experiments with split-brain patients. Only this time, he added a little twist.

In one example, he started by flashing a patient with two pictures.

The left hemisphere saw a chicken foot, and the right saw a snow scene.

Thanks to previous research, he knew that the left is where language skills are centered, and the right is holistic and sensual and has no words for what it sees.

Gazzaniga then asked the subject to choose related images for each picture from an array visible to both brain halves.

These were things like a fork, a shovel, a chicken and a toothbrush.

The patient chose a chicken to go with the foot and a shovel to go with the snow.

So far, everything made sense.

Rationalizing After the Fact

Next, Gazzaniga asked the subject why he chose those particular items.

The patient quickly replied: “The chicken goes with the foot.”

The left hemisphere had seen the foot. It also had a good rationale for connecting it with the chicken and words to describe it with.

But his left brain hadn’t seen the picture of the snow, only the shovel.

He had chosen the shovel instinctively with no conscious explanation for it.

When Gazzaniga asked him to explain his choice, the subject searched his left brain for the symbolic representation of the snow and found nothing.

But instead of saying “I don’t know,” he looked down at the picture of the shovel and said: “And you need a shovel to clean out the chicken shed.” (3)

The Interpreter

The left hemisphere just threw out an explanation of what it could see: the shovel.

In subsequent studies, Gazzaniga and other researchers have found that this pattern is consistent.

The left brain takes the information it gets and tells a story about it to our conscious awareness.

Gazzaniga refers to this system as “The Interpreter” (4), and it seems always to want to explain our moods and actions after they’ve occurred.

The reason we can make sense of everything that goes on in our heads is that The Interpreter is providing a never-ending narration about what’s going on.

The Interpreter takes everything we perceive and think about and turns it into a story that makes sense.

The Flawed Brain

We tend to take our thoughts very seriously. If a thought pops up and tells us about what’s going on in a particular situation, we’re likely to consider that thought an objective truth.

But it’s not. It’s just The Interpreter in your left hemisphere putting together yet another narrative to make sense of the world.

And it does so with incomplete information, limited senses, and a ton of cognitive biases that distort the story (5).

So, we all have an inaccurate view of what is really going on in any given situation.

That’s just part of the human condition.

(Oh, and if right now you’re thinking this doesn’t apply to you, remember where that thought is coming from. That’s right — your friend, The Interpreter.)

Choosing What to Believe

Accepting that we perceive the world inaccurately can be a tough pill to swallow.

But I actually find it to be quite inspiring.

Because if there’s no way to know for sure what is going on, that means you get to choose what to believe.

And by becoming aware of The Interpreter, you can develop the ability to question the thoughts and narratives in your head.

You can examine your beliefs, remove the ones that aren’t helpful, and put empowering convictions in their place.

That practice can have huge implications for your life.

Your Beliefs Become Your Reality

As I’ve written about before, research has found that:

  • Students who believe they can change their intelligence through hard work do better academically compared to students who believe their intelligence is a fixed trait (6).
  • Merely believing that your job provides a good amount of exercise is enough to lose weight, drop BMI and decrease blood pressure (7).
  • Your beliefs about how much calories a drink contains affect how much hunger hormone gets released in your body after drinking it (8).
  • If you believe stress is harmful, you’ll experience more stress than people who don’t (9).
  • Mindsets even affect your life expectancy. That is because individuals with a negative aging mindset are less likely to proactively engage in healthy behaviors such as eating healthy, exercising and visiting the doctor (10).

One belief can flood your system with stress hormones. Another one can make you feel calm and confident.

A Practical Example

The Father of American psychology, William James (11), claimed that: “The greatest weapon against stress is our ability to choose one thought over another.”

Let’s say you’re about to speak in front of a lot of people and you’re feeling nervous.

Your interpreter shows up and says: “Yup, you’re in way over your head this time. You’re going to fail miserably. Everyone is going to see it. And obviously, you’re stressing out about it.”

If you believe that, you’re going to be a mess, and your performance will most likely suffer from it.

But you can also step in and choose another belief: “This is not stress. It’s excitement. And that’s a good thing because it means my body is preparing for a great performance.”

That won’t necessarily make the feeling go away, but you’ll interpret it differently.

And that’s all you have to do to increase your chances of a great performance significantly (12).

Change Your Beliefs, Change Your Life

The Stoic philosopher Epictetus once said: “It’s not what happens to you, but how you react to it that matters.”

In light of this research, perhaps we should say: “It’s not what The Interpreter says, but whether you choose to believe it, that matters.”

This simple idea can make a huge difference.

And it goes way beyond stage fright.

If you want, you can use it to examine and change your most deeply held beliefs.

And it all starts with becoming aware of The Interpreter is telling you.

Remind yourself that what it’s telling you is not the truth. It’s just a narration to help you make sense of the world.

And if that particular story isn’t helpful to you, then switch it out.

You get to decide what to believe, so choose wisely.


  1. Split-brain
  2. Epilepsy and the Corpus Callosotomy
  3. How We Learn: The Surprising Truth About When, Where, and Why It Happens by Benedict Carey
  4. Left brain interpreter
  5. List of cognitive biases
  6. Implicit Theories of Intelligence Predict Achievement Across an Adolescent Transition: A Longitudinal Study and an Intervention
  7. Mind-Set Matters: Exercise and the Placebo Effect
  8. Mind Over Milkshakes: Mindsets, Not Just Nutrients, Determine Ghrelin Response
  9. Rethinking Stress: The Role of Mindsets in Determining the Stress Response
  10. Longevity Increased by Positive Self-Perceptions of Aging
  11. William James
  12. Get Excited: Reappraising Pre-Performance Anxiety as Excitement

Patrik Edblad

Written by

I write about timeless ideas and science-backed strategies to feel great and perform at your very best. Get more from me at

Better Humans

Better Humans is a collection of the world's most trustworthy writing on human potential and self improvement by coaches, academics, and aggressive self-experimenters. Articles are based on deep personal experience, science, and research. No fluff, book reports, or listicles.

More from Better Humans

More from Better Humans

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch
Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore
Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade