Descartes’ Error summary

To study the brain through the lens of experimental neuropsychology, we first need to find some before-and-after stories of people who have suffered specific types of brain damage. There are many such stories – but few of them are as vivid, grisly, or bizarre as that of Phineas Gage. 

The key message in this blink is: The story of Phineas Gage provides a dramatic example of how brain damage can provide us with scientific clues.

So what exactly happened to Phineas Gage?

Barring the invention of a time machine, we’ll never know for sure. Gage died in 1861, and his brain is no longer around for us to examine. But his skull has been preserved by Harvard Medical School, and we can study it for clues.

Let’s sum up what we’ve learned so far: if you suffer severe damage to your VPC, you lose your ability to engage in practical reasoning. The one therefore depends on the other, right?

Yes. In fact, the correlation between the two things has been firmly established. The author and his colleagues have studied 12 other patients who exhibit the same type of brain damage and cognitive symptoms. But as the old saying goes, correlation does not equal causation, so we need to be careful in drawing conclusions here.

As we continue on our journey to unravel the mystery of practical reasoning, we now have three suspects, instead of just one: the VPC, the limbic system, and the somatosensory cortex. What do these three parts of the brain have in common? To answer this question, let’s go back to the story of Elliot.

The key message here is: Further observations of Elliot’s behavior led the author to a surprising revelation. 

At first glance, the correlation between Elliott’s flatness of emotion and his diminished practical reasoning abilities seems pretty counterintuitive. After all, we usually think of our emotions as clouding our judgment. Without any pesky emotions getting in the way, shouldn’t Elliott be better at practical reasoning instead of worse?

As it turns out, our emotions have a lot more practical value than we usually give them credit for.

After suffering damage to his VPC, Elliot’s emotional life was severely diminished – but it wasn’t entirely destroyed. As we’ve seen, he could still experience occasional outbursts of anger. But they were like bolts of lightning flashing across an otherwise neutral sky.

That’s because Elliot could still experience primary emotions. These are the most basic forms of emotion, hardwired into us from birth. They include simple, short-lived states of happiness, sadness, anger, fear, and disgust. Elliot could still feel these just like anyone else. If you hid behind a door and suddenly jumped out in front of him, he’d still get frightened. 

Now imagine you come across a snake again, but this time, you’re a herpetologist – someone who studies reptiles and amphibians. You’ve been around snakes all your life, and you feel totally comfortable with them. And now you’ve just encountered a rare and harmless snake that’s been your favorite species since you were a child.

Now what emotion are you feeling? It’s no longer fear; you’re overjoyed! What you’re experiencing now is a secondary emotion. 

We’re now almost ready to solve our case. We’ve seen how the limbic system, the somatosensory cortex, and the VPC all come together in producing secondary emotions. And we’ve also seen how emotions can provide us with important information and guidance. Now we just need to put all of these pieces of the puzzle together.

Our mystery boils down to one final question: What role do secondary emotions play in our practical reasoning? To answer this question, let’s go back to Elliot’s story one last time.

Let’s end by returning to our final question: What role do secondary emotions play in our practical reasoning?

We’ve been pursuing a mystery in which the main suspects are the limbic system, the somatosensory cortex, and the ventromedial prefrontal cortex. If you were hoping the answer would have a more melodious name, you’re going to be disappointed. It’s called the somatic marker hypothesis – but it’s a lot more interesting than it sounds!