The Gazzaniga Effect: How You Fake Reasons For Your Actions
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The Gazzaniga Effect: How You Fake Reasons For Your Actions

In the 1960s, a young psychologist was hired to look for after-effects in patients who recently had split-brain surgeries. He discovered that they sometimes didn’t know the true motives for their behavior. Instead, they simply fabricated reasons to explain it. His fascinating discovery is still true 50 years later and also applies to us. Understanding why we fabricate reasons to explain our behavior gives us the opportunity to uncover our true motives.

Beginning in the 1960s, the surgent Joe Bogen cut the brains of patients in half who suffered from dangerous seizures. He knew that seizures start at a single spot in the brain and spread to the surrounding brain tissue and hoped that his surgery could reduce their recurrence. Therefore, he severed the corpus callosum that connects the two hemispheres of the brain to prevent the seizures from spreading.

His surgery had the desired effect: his patients experienced shorter and less intense seizures.

Shortly thereafter, the young psychologist Michael Gazzaniga was hired to look for possible after-effects of Bogen’s surgery. To check, Gazzaniga designed an experiment around the fact that the two hemispheres of the brain are specialized for different tasks. First, he made his patients look at a screen. Then, Gazzaniga flashed pictures of objects on either side of it so quickly that only one of their hemispheres could register them.

In one session, he flashed the image of a hat to both hemispheres of a patient. He then asked, “What did you see?” The patient replied: “A hat.” Thereafter, Gazzaniga flashed the same image only to the left hemisphere and repeated his question. Again, the patient said: “A hat.” Surprisingly, when Gazzaniga flashed the same image only to the right hemisphere and repeated his question, the patient reported that he had seen nothing. But, when Gazzaniga showed him several pictures of objects afterward and asked him to use his left hand to point to the one he had seen, the patient pointed to the hat.

When Gazzaniga flashed different pictures to each of the two hemispheres, things grew weirder. Once, he flashed a picture of a chicken claw to the right side of the screen and a picture of a house and a car covered in snow to the left. Then, he showed his patient different pictures and asked her to point to the one that “goes with” what she had seen. Her right hand pointed to a picture of a chicken, but her left hand pointed to a picture of a shovel. When Gazzaniga asked her to explain her responses, she didn’t say, “I have no idea why my left hand is pointing to the shovel.” Instead, she immediately made up a plausible story: “Oh, that’s easy. The chicken claw goes with the chicken, and you need a shovel to clean out the chicken shed.”

In another bizarre case, Gazzangi flashed the word “walk” to the right hemisphere of one of his patients. Often, the patient would stand up and walk away. When asked why he was getting up, he didn’t say: “I have no idea why I’m getting up.” Instead, he said, “I’m going to get a Coke.”

At first, Gazzangi was puzzled. But, after a few more experiments, he understood that the right hemisphere of his patients was unable to verbally report what it had seen. To do that, it needed the language center of the left hemisphere which it couldn’t access. Gazzaniga’s patients thus had no idea that the flashed pictures were the true reason for their behavior. Instead, they quickly invented plausible stories that seemed to explain it.

As a result of his experiments, Gazzaniga described the language center in the left hemisphere as an “interpreter module”. He noted that his job was to give running commentary on whatever the self was doing, even though the interpreter module had no access to the true causes or motives of the self’s behavior. Gazzaniga had discovered what psychologists now call “confabulation.” The fact that we readily fabricate reasons to explain our behavior even if we don’t know our true motives.

While most of us don’t have a split brain, we confabulate too. We invent convincing explanations for our behavior, even though we have no idea of our true motives. But, equipped with our new knowledge, we can now catch ourselves confabulating. Be it in arguments with our partner, in quiet moments of self-reflection, or discussions with friends.

If we’re honest with ourselves, we will more often say: “I don’t know why I did that.” We can even catch ourselves in the act of confabulating. Then we can stop ourselves from confabulating and pay close attention to discover our true motives. Further, by using tools like journaling, meditation, or conversations with friends we can try to uncover the true motives and reasons behind our behavior. Doing this can help us understand ourselves better, make better decisions, and live more authentically.[1]

  1. “The Happiness Hypothesis” by Jonathan Haidt inspired this essay. You can find most of the science that this essay is based on, as well as further reading, on pages 6-10. ↩︎

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