Scientists from the UK’s University College London (UCL) have discovered that people who are good at introspection, such as reflecting on their ideas, emotions and behaviour, the so-called “thinking about thinking” processes that set us apart from other animals, have a bigger associated area of the brain.

You can read how Dr Geraint Rees, a Wellcome Trust Senior Fellow and professor at UCL’s Institute of Cognitive Neuroscience and Wellcome Trust Centre for Neuroimaging, and colleagues, arrived at this conclusion in a paper published 17 September in Science, a journal of the American Association for the Advancement of Science (AAAS).

Joint first author Dr Steve Fleming told the press that we all think about our own thoughts, feelings and decisions: “it’s something we do all the time, but some people are better at it than others,” he said, adding that:

“Even if we don’t get feedback when we make a choice, we often know intuitively if it’s a good or a bad decision.”

Introspection is not like learning or decision-making, which can be assessed by measuring improvement in the performance of a task, or whether choices are made correctly.

Measuring introspection is somewhat more challenging: there are no outward signs of when it improves.

To meet this challenge, Rees and colleagues designed an experiment that did two things: measured objective performance of a task and how well a person judged their own performance. In other words, it measured how good they were at thinking about their decisions, or introspection.

For the study they recruited 32 healthy volunteers and asked them to look at two screens showing the same identical patterned patches: except that on one screen one of the patches was brighter than the other 5.

The researchers asked the volunteers to say which screen showed the bright patch and then to rate how confident they felt about their decision (before they knew if it was right or wrong).

The point wasn’t to allow them to change their mind after they had made their choice, but simply to get a measure of how confident they felt about it.

The researchers designed the task to be difficult, so that the volunteers were never completely sure if their answers were right or wrong. They reasoned that volunteers who are good at introspection would be confident after making correct decisions and less confident when they were incorrect.

(Note the important distinction between this and confidence itself: people who are confident even when they make the wrong decision are not as good at introspection as the ones whose lower confidence more accurately reflects the difficult of the choice. In other words, being cocky is not necessarily a sign of high introspection!)

The researchers adjusted the difficulty of the task so that all volunteers performed equally well on it, and all that differed was their introspective ability.

Joint first author Dr Rimona Weil said the experiment was like the game show “Who wants to be a Millionaire?”, where “a good contestant will go with their answer when they’re sure, and phone a friend if unsure. But a poor contestant might not be as good at judging how likely they are to be correct”.

After the experiment, the researchers then took magnetic resonance imaging (MRI) scans of the volunteers’ brains looking for parts of the brain that seemed to correlate with introspective ability.

Rees said they found a link between introspective ability and the structure of a small part of the prefrontal cortex near the front of the brain:

“The better a person was at introspection, the more grey matter they had in this area,” he added.

He said the same was also true of the white matter, or the nerve connections in the same area:

“At this stage, we don’t know why their grey or white matter differs in this small area,” said Rees.

The researchers stressed that their study does not show a cause and effect, only a link. As Rees said, the question still remains:

“Does this area develop as we get better at reflecting on our thoughts, or are people better at introspection if their prefrontal cortex is more developed in the first place?”

However, Rees and colleagues hope their discovery will increase our understanding of why and how brain damage affects people’s ability to reflect and think about their thoughts, and perhaps help us devise appropriate treatments or interventions.

Fleming illustrated the hypothetical case of two patients with mental illness where one is aware of it and the other is not:

“The first person is likely to take their medication, the second less likely,” he explained.

“If we understand self-awareness at the neurological level, then perhaps we can adapt treatments and develop training strategies for these patients,” said Fleming, who suggested there could be different levels of consciousness, ranging from simply having an experience to thinking about that event and its effects.

“Introspection is on the higher end of this spectrum – by measuring this process and relating it to the brain we hope to gain insight into the biology of conscious thought,” he added.

Funds from the Wellcome Trust, the UCL Four Year PhD in Neuroscience and the Medical Research Council paid for the study.

“Relating Introspective Accuracy to Individual Differences in Brain Structure.”
Stephen M. Fleming, Rimona S. Weil, Zoltan Nagy, Raymond J. Dolan, and Geraint Rees.
Science, Vol. 329. no. 5998, pp. 1541 – 1543, 17 September 2010
DOI: 10.1126/science.1191883

Sources: UCL, AAAS.

Written by: Catharine Paddock, PhD