The Limits of Rational Thought

A couple of months ago a friend of mine recommended I pick up Richard Power's new novel The Echo Maker. "It's right up your alley," he said, "It's all about a man suffering from a bizarre brain condition." I added it to my Amazon shopping cart within the hour.

In The Echo Maker, Powers' character Mark flips his truck on an icy stretch of road in Nebraska and ends up in the hospital in a near-vegetative state. His sole-remaining family member, his sister Karin, immediately rushes to his bedside to nurse him back to health. Mark remains comatose for long enough that the doctors begin to lose hope. But then, miraculously, he wakes up. It takes him weeks to regain the power of speech, but once he does, it becomes clear that something is seriously amiss: Mark is convinced that this person who hovers by his bedside at all hours of the day, who looks and sounds just like his sister, is a plant--an imposter sent to surveil him and report back to "the authorities."

Powers soon reveals that Mark is suffering from a condition known as Capgras Delusion, which just so happens to be my favorite neurological condition. Once thought to be undeniable evidence of psychosis, Capgras Delusion is now believed to be a neurological syndrome caused by faulty wiring between the two areas of the brain involved in facial recognition: the temporal lobe, which contains pathways specializing in identifying faces, and the limbic system, which is responsible for attributing emotional significance to these faces.

You may be wondering what fuels my fascination with such a bizarre mental disorder - and I won't lie: morbid curiosity plays a large role - but another reason I find Capgras Delusion so intriguing is that it gives us some insight into the limits of rational thought.

Human beings tend to think of the brain as the body's chief executive and rational thought as the predominant force in our daily lives. Some of us grudgingly admit that the subconscious plays a role, but we waste little time contemplating what that role is outside of the confines of our therapist's office. In our daily lives, we cleave to the belief that our logical brains are in the driver's seat. Occasionally, the Id rears its ugly head - prompting us to eat half a pecan pie, drink more than the recommended dosage of red wine, or tumble into bed with an attractive stranger - but by and large, we're able to curb these impulses and let reason guide us. Right? Not necessarily. Our decision-making processes are dictated by a number of "irrational" factors and Capgras Delusion is the perfect example of how these factors can short circuit the logical mind.

When we encounter a face, two things occur in the brain. Our visual centers survey the physical attributes of the person in front of us and match them up with a template stored in the temporal lobe, thus allowing us to classify the person. This information then gets transmitted to the limbic system, which conjures up the appropriate feelings.

People suffering from Capgras Delusion only experience the first half of this process. Because their temporal lobes are in tact, they recognize that the person standing in front of them looks exactly like their mother, but this recognition evokes no emotional response. The way the brain copes with this disjunction is by making a logical leap: 'This person looks like my mother, but doesn't feel like my mother, therefore she must be a fraud.'

Now if the person suffering from Capgras was unaware of his impairment, this response would be entirely understandable. What's really mystifying is that explaining what's happening makes absolutely no impression on the patient. No matter how many times he's told that he's suffering from a neurological condition, he will persist in believing that he's being hounded by doppelgangers. If the rational brain was at the reins, it stands to reason that the patient would accept his doctor's explanations. But when it comes to Capgras Delusion, emotions trump logic. The mind simply cannot accept the idea that a spouse, a mother, or beloved sister elicits no feeling, so the delusion persists.

People often assume that allowing emotions to color their decision-making process is a mistake - and in the case of Capgras Delusion, it is - but this is the exception to the rule. As Jonah Lehrer, the brain behind Science Blogs' The Frontal Cortex, noted in his recent lecture "Walt Whitman's connection to modern neuroscience," emotions are essential to healthy functioning. We hyper-rational denizens of the modern world are in the habit of overestimating the importance of logic, but without emotions, the rational mind is entirely incapacitated.

In this fascinating lecture, Lehrer argues that recent scientific findings have proven that Walt Whitman was correct in his assumption that the body and the mind are of a piece. As evidence, Lehrer cites the research of famed University of Iowa Neurologist Antonio Damasio. Damasio spent years studying patients who couldn't generate emotions because they lacked the brain regions necessary for interpreting physical sensations, like the pounding of the heart. These emotional invalids suffered from myriad problems, but their most marked feature was an inability to make even trivial decisions. As Lehrer says:

Damasio's emotionless patients proved incapable of making reasonable decisions . . .They would literally sit there for three hours in the morning trying to choose between Cheerios or Honey Nut Cheerioes. And Damasio's conclusion is that unless you have the emotional inputs, you can never evaluate between the logical possibilities.

Whitman once said that, "If our consciousness was severed from the body, there would be no mind stuff left behind," Lehrer tells us, and modern neuroscientists are beginning to concur. We in the West have been weaned on the notion that rationality is paramount, but it's time to relinquish the idea that the logical mind can operate independently. As Damasio once said "rationality is actually intimately connected with emotions." We need to take a page out of Whitman's book and place more trust in our instincts.

Unconvinced? Take a look at this recent study conducted by researchers at University of College London, which found that "instinctive snap decisions are more reliable than decisions taken using higher-level cognitive processes."


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I would ask, though, if chosing between 'regular' cheerios and honey nut is a "reasonable decision".

I mean, /logically/ there should be little to differentiate. This is not the case if someone were to ask something like 'which would you rather do, eat dirt or shoot a puppy'.

Because the cheerio decision is so seemingly lacking in importance/difference, doesn't it make sense that all you have to go on are instinctive emotions? Then isn't the point obvious?

Or am I missing the point. I do that sometimes :(

being experienced with both learning disabilities ADHD, NVLD and modd disorders (depression, anxiety) I've had all too much experience with the limits of rational thought -- both in myself and others.

By David Harmon (not verified) on 11 Jan 2007 #permalink

Waly Whitman, were he alive today, would be blogging like crazy. Here's a book review he might have written, for example:

Jonathan Vos Post
(as if Walt Whitman reviewed the novel "Less Than Zero")

Less Than Zero? NO! I am More Than One.

I am more than one, half my father and half my mother, and more
I am one-fourth each of all four grandparents, and more
Each brother and each sister is half of me, and I am half of them,
and all the people of the world are my brothers and my sisters, and more
and there is more than one world; I choose this world, and more

I am part of every group, and more than all those groups I choose to join
I am a representative of every trait I manifest, and more
I take part in every belief I choose to hold, but I am more than my beliefs
I am, in part, each thought and memory and feeling, but more than all parts..

[truncated, follow hotlink for more]

Is this syndrome related to the one Oliver Sacks describes where parts of ones own body are perceived to be "alien" objects?

Just for the record, it doesn't take my id to "tumble into bed with an attractive stranger" - I blame the id for the unattractive strangers.

In the recent study posted near the end, snap judgments were more accurate than the rational mind only within the first 4 seconds. After 4 seconds, accuracy was recovered.

Since this is in reference to identifying something visual, similar to a "Where's Waldo" picture, I don't see how it applies to items that are complicated in nature.

As Wesley pointed out, deciding between two trivial items such as what flavor of Cheerios might require some emotional feedback but when analyzing complex scenarios such as the war in Iraq, sober rationality might work better than any emotional tie.


BTW: Consider me delurked

By Noamchimpsky (not verified) on 12 Jan 2007 #permalink

***Is this syndrome related to the one Oliver Sacks describes where parts of ones own body are perceived to be "alien" objects?***

Sounds like anosognosia (lacking awareness/denial of deficit, particularly paralysis) which is commonly a result of right hemisphere lesion from stroke. Damasio's quote, I would gather, was focused on ventromedial PFC patients.

There may be some links between them as the right hemisphere is viewed by many as the emotional hemisphere and some researchers are assessing a possible emotional cause (along with the obvious hemiplegia), and the VMPFC is part of the emotional circuitry (representing value of stimuli). So both could have an emotional deficit as a factor.

By melatonin (not verified) on 12 Jan 2007 #permalink

Ahhh, I see crster was talking about capgras...

Capgras also seems to be an emotional disorder, as these people seem to lose the association of familiar faces with their emotional 'label'. So, if you see a loved one, you recognise the face but lack the positive emotion you know you should feel, they view them as an imposter or 'alien'.

By melatonin (not verified) on 12 Jan 2007 #permalink