Feeling our way to decision
Emotions don’t impede rational thought, they underpin it, writes Jonah Lehrer in today’s Sydney Morning Herald.
Elliot had a small tumour cut from his cortex near the brain’s frontal lobe. He had been a model father and husband, holding down an important management job in a large corporation and was active in his church. But the operation changed everything.
Elliot’s IQ stayed the same – testing in the smartest 3 per cent – but, after surgery, he was incapable of decision. Normal life became impossible. Routine tasks that should take 10 minutes now took hours. Elliot endlessly deliberated over irrelevant details: whether to use a blue or black pen, what radio station to listen to and where to park his car. When contemplating lunch, he carefully considered each restaurant’s menu, seating and lighting, and then drove to each place to see how busy it was. But Elliot still couldn’t decide where to eat. His indecision was pathological.
Elliot was soon sacked. A series of new businesses failed and a con man forced him into bankruptcy. His wife divorced him. The tax office began investigating him. He moved back with his parents. As neurologist Antonio Damasio put it: “Elliot emerged as a man with a normal intellect who was unable to decide properly, especially when the decision involved personal or social matters.”
But why was Elliot suddenly incapable of making good decisions? What had happened to his brain? Damasio’s first insight occurred while talking to Elliot about the tragic turn his life had taken. “He was always controlled,” Damasio remembers, “always describing scenes as a dispassionate, uninvolved spectator. Nowhere was there a sense of his own suffering, even though he was the protagonist … I never saw a tinge of emotion in my many hours of conversation with him: no sadness, no impatience, no frustration.” Elliot’s friends and family confirmed Damasio’s observations: ever since his surgery, he had seemed strangely devoid of emotion, numb to the tragic turn his own life had taken.
To test this diagnosis, Damasio hooked Elliot to a machine that measured the activity of the sweat glands in his palms. (When a person experiences strong emotions, the skin is literally aroused and the hands start to perspire.) Damasio then showed Elliot various photographs that normally triggered an immediate emotional response: a severed foot, a naked woman, a house on fire, a handgun. The results were clear: Elliot felt nothing. No matter how grotesque or aggressive the picture, his palms never got sweaty. He had the emotional life of a mannequin.
This was an unexpected discovery. At the time, neuroscience assumed that human emotions were irrational. A person without emotions should therefore make better decisions. His cognition should be uncorrupted. The charioteer should have complete control. To Damasio, Elliot’s pathology suggested emotions are a crucial part of decision-making. Cut off from our feelings, the most banal decisions become impossible. A brain that can’t feel can’t make up its mind.
Damasio began studying other patients with similar brain damage. These all appeared intelligent and showed no deficits on any conventional cognitive tests. And yet they all suffered from the same profound flaw: because they didn’t experience emotion, they had tremendous difficulty making decisions.
In his earlier book, Descartes’ Error: Emotion, Reason And The Human Brain, Damasio described trying to set up an appointment with an emotionless patient: alternative dates are suggested and the patient pulls out an appointment book and consults the calendar. For 30 minutes the patient enumerated reasons for and against each of the two dates: previous engagements, possible meteorological conditions, virtually anything that one could reasonably think about. “He was now walking us through a tiresome cost-benefit analysis, an endless outlining and fruitless comparison of options and possible consequences. It took enormous discipline to listen to all of this without pounding on the table and telling him to stop,” Damasio wrote.
Based on these patients, Damasio began compiling a map of feeling, locating the specific brain regions responsible for generating emotions. Although many cortical areas contribute to this process, one part seemed particularly important – the orbitofrontal cortext, a small circuit of tissue sitting just behind the eyes, in the underbelly of the frontal lobe. If this fragile fold of cells is damaged by a malignant tumour or a hemorrhaging artery, the tragic result is always the same.
After treatment, everything seems normal at first. A full recovery is forecast but little things start to go awry. The patient begins to seem remote, cold, distant. This previously responsible person suddenly starts doing irresponsible things. The mundane choices of everyday life become excruciatingly difficult. It’s as if his very personality – the collection of wants and desires that defined him as an individual – had been systematically erased. His loved ones say it’s like living with a stranger, and one that has no scruples.
The crucial importance of our emotions – the fact that we can’t make decisions without them – contradicts the conventional view of human nature, with its ancient philosophical roots. For most of the 20th century, the ideal of rationality was supported by scientific descriptions of human anatomy.
The brain was envisioned as four separate layers, stacked in ascending order of complexity. (The cortex was like an archaeological site; the deeper you dug, the further back in time you travelled.) Scientists explained the anatomy of the human brain in this manner: at its bottom was the brain stem, which governed the most basic bodily functions. It controlled heart beat, breathing and body temperature. Above that was the diencephalon, which regulated hunger pangs and sleep cycles.
Then came the limbic region, which generated animal emotions. It was the source of lust, violence and impulsive behaviour. (Human beings shared these three brain layers with every other mammal.) Finally, there was the magnificent frontal cortex – the masterpiece of evolution – which was responsible for reason, intelligence and morality. These convolutions of grey matter allowed each of us to resist urges and suppress emotions. In other words, the rational fourth layer of the brain allowed us to ignore the first three layers. We were the only species able to rebel against primitive feelings and make decisions that were dispassionate and deliberate.
But this anatomical narrative is false. The expansion of the frontal cortex during human evolution did not turn us into purely rational creatures, able to ignore our impulses. In fact, neuroscience now shows that the opposite is true: a significant part of our frontal cortex is involved with emotion. David Hume, the 18th-century Scottish philosopher who delighted in heretical ideas, was right when he declared that reason was “the slave of the passions”.
How does this emotional brain system work? The orbitofrontal cortex (OFC), the part of the brain that Elliot was missing, is responsible for integrating visceral emotions into decision-making. It connects the feelings generated by the “primitive” brain – areas such as the brain stem and the amygdala, which is in the limbic system – to the stream of conscious thought.
When a person is drawn to a specific receiver, or a certain entree on the menu, or a particular romantic prospect, the mind is trying to tell him that he should choose that option. It has already assessed the alternatives (this analysis takes place outside of conscious awareness) and converted that assessment into a positive emotion. When he smells a food he doesn’t like, or glimpses a former girlfriend, it is the OFC that makes him want to get away. The world is full of things, and it is our feelings that help us choose among them.
When this neural connection is severed – when our OFCs can’t comprehend our own emotions – we lose access to the wealth of opinions we normally rely on. It’s impossible to make decent decisions. This is why the OFC is one of the few cortical regions that are markedly larger in humans than they are in other primates. While Plato and Freud would have guessed that the job of the OFC was to protect us from our emotions, to fortify reason against feeling, its actual function is precisely the opposite. Humans are the most emotional animal of all.
This is an edited extract from Jonah Lehrer’s The Decisive Moment: How The Brain Makes Up Its Mind, to be published next week in Australia by Text Publishing.