Our ability to introspect, in other words, to think about our thinking, is a key aspect of human consciousness and is important in all sorts of activities. Just think about a student studying for a test, her ability to introspect on whether she has understood the material in the textbook is imperative for ensuring a good grade on the exam. If our student finishes reading the textbook without knowing she hasn't understood it, her likelihood of acing the exam is not very high. Or, how about in the hospital? If a doctor has high confidence that she has made the right diagnosis of a patient, but this confidence is not actually justified (i.e., the diagnosis is wrong), this may prevent her from seeking additional tests or that second opinion that could save the patient's life. In short, our ability to accurately introspect on our understanding is essential for the appropriate guidance of our decisions and actions in most facets of life.
For some time now, psychologists have know that some people are better at judging the accuracy of their knowledge and decisions than others. A paper published last month in Science shows where this introspective ability is rooted in the brain. It also provides some interesting insights into whether or not we can actually improve our ability to think about our own thinking.
Dr. Stephen Fleming and his colleagues at University College London asked people to engage in a visual decision making task in which the goal was to chose which patch in a series of images was brightest. Because some people are better at this type of decision than others, the researchers programmed a computer to give harder trials to the better observers, and easier trials to the poorer observers. This meant that everyone's performance was at roughly the same accuracy level. People were also asked to rate how confident they were in their decisions which gets at our ability to introspect. The more of a match between people's decision-making accuracy and their confidence, the better their introspective abilities.
The researchers then related this introspective ability to the structure of people's brains. They used magnetic resonance imaging (MRI) to do this. They found that introspective ability correlated with increased gray matter volume (which implies more neuron cell bodies) in the anterior prefrontal cortex. In people better at introspection, the researchers also found enhanced integrity and efficiency of the neuronal fibers (white matter tracts) that connected the anterior prefrontal cortex to other brain regions. The anterior prefrontal cortex shows marked evolutionary development in humans. It sits at the top of the information processing hierarchy and is thought to be involved in linking information about performance and confidence.
It's too soon to tell whether these findings reflect innate differences in brain anatomy or are the result of experience or learning. Indeed, the current findings can't settle this issue. However, this research does hint at the intriguing idea that we may be able to train introspective ability by capitalizing on the malleability of the prefrontal cortex. Other work suggests that practice can change how the brain is wired to support exceptional performance. This might be true in terms of introspection as well.
Take London cab drivers, for example. They learn every street in a city because they practice. London cab drivers spend several years memorizing various ways to navigate their crowded metropolitan area before they are allowed to set foot in their own cab. Scientists have shown that this route-finding practice changes these cab drivers' brains.
The hippocampus, which is important for navigating and recalling complex routes, is enlarged in London cabbies compared to non-drivers. Even more telling about the role of practice in changing the brain is that the size of cab drivers' hippocampus varies with years spent behind the taxi wheel. The longer a driver has been on the streets, the larger the part of the hippocampus involved in successfully finding the correct city route.
Just as experience changes the brains of cab drivers to support exceptional navigation, training regimens designed to mold the prefrontal cortex to support exceptional introspection might be possible as well. If so, then in addition to doctors practicing in the operating room, brain training designed to increase doctor's ability to accurately introspect on their own knowledge and decisions may help ensure optimal performance in the medical field.
For more on brain training and enhancing performance, check out my book CHOKE. In stores now!
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Fleming, Weil, Nagy, Dolan, & Rees (2010). Relating introspective accuracy to individual differences in brain structure. Science, 329, 1541-1543.
