Summary of Descartes’ Error by Antonio Damasio

BookSummaryClub Blog Summary of Descartes’ Error by Antonio Damasio

Back in the seventeenth century, Rene Descartes put forward a theory that the mind and body are not separate entities as previously described. Descartes believed that the mind controls the body and that the body could also influence the mind. This became known as Cartesian Dualism. Nowadays, researchers tend to look more closely at this dualism in the form of body and mind or reason and emotion. They do this to try and figure out how our brain can reason, can it overcome passionate emotion and what bodily actions occur due to this. 

Dualism is no longer a way we can describe the body and mind because we know better. We already know that the brain, body and emotions are all linked and the impact they each have on each other varies with each individual. But how do we begin to understand how much? 

In this book summary readers will discover:

  • How the different regions of the brain are studied and how it was inspired
  • The ventromedial prefrontal cortex and Elliot
  • The surprise about emotions

Key lesson one: How the different regions of the brain are studied and how it was inspired

The brain is an incredible machine and just like any complex machine, it is made up of many parts. In order to figure out which part is responsible for what action, means taking the machine apart and seeing what happens when it is removed from the machine. However, doctors can’t exactly do that with the human brain. Therefore, they needed to find another way. 

Their answer came in the form of injuries, tumours and diseases which affect certain areas of the brain. In some cases, these ailments can only interfere with one part of the brain thereby allowing the rest of the brain to remain intact and functioning. This allows doctors to study how the patient is affected when a single region is impaired. An example of this is an injury to the third frontal gyrus. An injury to this area leads to a language disorder called aphasia. This allowed doctors to identify the third frontal gyrus as an area that plays a role in the way the brain processes language. In this way, doctors are able to create a map of the brain together with what it controls or plays a part in.

This type of study is not new. Experimental neuropsychology has actually been around for some time with many interesting cases. But none has stood out in history like that of Phineas Gage. Gage was a construction foreman from Vermont. He was a trusted employee of the Rutland & Burlington Railroad company and was so dependable that they let him oversee the explosive demolitions needed for the railroad construction. It was in doing this job that tragedy struck. One of the explosives that he had set was accidentally triggered causing a thin metal rod to pierce Gage’s cheek. The force of the explosion caused the rod to go straight through his cheek, enter the bottom of his skull, pass through his brain and exit at the top of his skull. The rod landed 100 feet away from Gage and left his coworkers thinking that Gage was dead. However, Gage surprised everyone by sitting up and talking to everyone only moments later. He was treated by a doctor and was deemed fit to continue. In the decade after the accident, Gage displayed normal brain activity. His cognition was not affected and neither were his memories, language, intelligence or perception. 

But, this did not mean that there were no consequences of the accident. Gage was described as being no longer himself. His behaviour changed drastically. He began swearing, lying and was impulsive. These were all characteristics he did not exhibit prior to his accident. His behaviour was so bad that he actually lost his job at the railroad company. He worked various small jobs after that before dying in 1861, 13 years after the explosion. 

Gage’s injury and story provided researchers with great insight into the brain. This was one of the first modern examples that showed that a particular area of the brain is responsible for our behaviour.

Key lesson two: The ventromedial prefrontal cortex and Elliot

Gage’s skull was preserved by Harvard Medical School so that it could be further studied. They used advanced computer simulation to try and track the trajectory of the rod that pierced Gage’s brain. Based on this, they found that the area of the brain that had been damaged was the ventromedial prefrontal cortex or VPC. 

To further reinforce their deduction, researchers looked for someone who currently had the same damage and symptoms as Gage. They found a patient who they refer to as Elliot. Elliot had damage to his VPC after developing a tumour in this area. He had been a successful businessman and after the discovery of the tumour, the rest of his brain was fully functional. However, observing Elliot in the real world revealed that there was something wrong with practical reasoning skills. His decision-making ability was severely impacted and he could not prioritize tasks or manage his time at work. Even simple tasks would lead to him getting distracted and doing something else which was completely unnecessary. As a result, Elliot lost his job and then began to invest his money in schemes that everyone tried to talk him out of. Elliot refused to listen and ended up bankrupt, unemployed and divorced. Much like Gage, he lost everything.

Researchers studied 12 other patients with the same brain damage and symptoms and they all showed a correlation between VPC damage and practical reasoning. However, all scientists know that correlation does not equal causation and when researching the brain, there’s hardly even just one region involved. So they also examined the damage to other regions of the brain that resulted in similar symptoms. They found two. The first was damage to the amygdala and the anterior cingulate that are both parts of the limbic system and are known to be involved with emotional processing. The second was damage to the right side of the somatosensory cortex. The area of the brain is involved in the physical sensations of touch, pain and temperature. This means that there are three regions of the brain involved in practical reasoning, the VPC, limbic system and the somatosensory cortex. The next thing to figure out is how they work together to perform this function? What exactly do emotions and physical sensations have to do with practical reasoning?

Key lesson three: The surprise about emotions

This led researchers to go back to Elliot and study him further. What they realised is, whenever they questioned Elliot about his life and what had happened thus far, he was able to tell them the story without any emotion. No matter how sad his story was, he never displayed any signs of emotion. He didn’t even get frustrated with the researcher’s neverending questions. They then questioned people in Elliot’s personal life to see if they had noticed the same thing. They all said exactly the same thing. Despite some brief moments of anger, he was mostly emotionless. The final test they conducted was to show Elliot a series of images that were meant to evoke emotion. Even Elliot then noticed that he did not experience emotion like he used to. It wasn’t only him either, the 12 other patients with damage to the VPC all showed the same result.

These results gave researchers another correlation between lack of emotion and practical reasoning. With this new information, they set out to find out just how our emotions can influence our practical reasoning. Many changes occur in our body for us to experience emotion. For example, when we are happy, the muscles in our face form a smile, the muscles in our body relax and our skin even flushes. These can be triggered by mental images in the form of memories, people, sounds and tastes. The combination of mental images and your body state make up an emotion. 

Knowing this, the researchers once again examined Elliot. His friends said he still exhibited some flashes of anger albeit for a short while. Upon further inspection, it was found that Elliot showed signs of primary emotions. These are the emotions that we possess from birth and are short-lived. They are happiness, sadness, anger, fear and disgust. Thus it was determined that people with VPC damage can still experience primary emotions because their limbic systems and somatosensory cortex are still functional. In contrast, people with damage to parts of the limbic system cannot experience primary emotions. Secondary emotions are more complex. The somatosensory cortex is needed to update you on your emotional body state, your limbic system creates that body state and the VPC combines these two signals to bring them together to experience the secondary emotion.

This leads to the final piece of the puzzle which can be summarized as one question. What do our secondary emotions have to do with our practical reasoning? This is where somatic markers come in. Somatic markers are best described as the markers that play an important part in our key decision-making processes. When we consider all our options and the outcomes that may result from them, we experience secondary emotions about them. These are either positive or negative and guide your decision. For example, let’s say you had an option for a meeting on either Monday or Wednesday. You look at the invite and the thought of a Monday meeting puts you off as it is the first day back after the weekend and you have too much work to do. This is something you know from your previous experiences. So, you immediately pick Wednesday as Monday evokes a negative emotion.

 If Elliot were given this option, he has no somatic markers that could guide him to a specific date. This means he doesn’t experience any emotion regarding either day so he battles to choose between the two days. He would consider every single possibility that could occur on either day and eventually still not make the decision. Life does not often provide us with a lot of time to make such decisions and thus our brain needs somatic markers to make reasonable decisions. This means that to be reasonable the brain has to listen to the body and the emotions that come with it. Thus reason and emotion are indeed linked.

The key takeaway from Descartes’ Error is:

The brain is an organ of much fascinations. For years, doctors and researchers have studied how it works and how each region can influence particular areas. Damage to specific areas of the brain allows researchers to determine the influence that particular region has. Practical reasoning was first thought only to be associated with the VPC. However, we now know that practical reasoning is guided by our emotions via somatic markers. Therefore, contrary to popular belief, emotion and practical reasoning are linked.

How can I implement the lessons learned in Descartes’ Error:

As an exercise, now that you are aware of them, try to identify your somatic markers. The decisions we make are guided by these secondary emotions. If you make a bad decision, try to identify the somatic marker that led you there. It may help you in future if you are aware of them and how they influence your decisions.

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