Read more: “Consciousness: The what, why and how“
THERE are many ways that human intelligence differs from that of animals, but one of the most obvious is our level of self-awareness. A pet dog, for instance, is probably aware of many sensations at any given moment: that it is hungry, that it is tired after a long walk, perhaps, and that there is a delicious smell emanating from the kitchen.
Its owner would be aware of all those sensations and yet would have an extra level of thought processes overlaying them. As a human, we can be aware that we are aware of our basic sensory inputs, and that allows us to reflect on the accuracy or validity of our feelings and judgements.
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That lets us think: “How tired I am after that long walk, it’s that satisfying kind of tiredness you get after exercise. But I’m not too tired to walk to the pub tonight.”
This faculty is often referred to as introspection or metacognition. “It’s the ability to self-reflect, to know about yourself,” says Steve Fleming, who studies consciousness at New York University. “This is something that we think is, if not unique to humans, at least one of the most developed faculties of human psychology.”
“THE ABILITY TO SELF REFLECT IS WHAT GIVES HUMANS THEIR SUPERCONSCIOUSNESS”
Fleming dubs this capacity our super-consciousness. “Metacognition seems to be quite core to who we are.”
Past research on metacognition has focused on whether it really is unique to humans or whether it is shared to some extent by the more intelligent animals. There have been hints of this capacity in dolphins and monkeys, for instance, although sceptics say there could be other for the results.
Scanning the brains of humans while they carry out metacognitive tasks suggests the seat of this ability lies in our prefrontal cortex, at the front of our heads. But this faculty has been hard to get the measure of. If we ask people how sure they are about their answers in a test, say, the results are muddled by the variation in people’s ability to do the test. So are you measuring ability or awareness of that ability?
Fleming’s team came up with a crucial extra step. The task they used was a simple visual one, showing people stripy patches in different shades of grey, and asking which had the greatest contrast (see picture). After each question subjects had to rate how confident they were that they had chosen the right answer.
Blindsight
Crucially, the contrast of the stripes was adjusted for each person so that, no matter how good their vision, everyone got about 70 per cent of the answers right. That meant that for the confidence ratings, the only variable was people’s metacognitive abilities, giving the first demonstration in the lab that this ability varies widely ().
As well as doing these tests, the volunteers also had their brain scanned, and this revealed that those with the best metacognitive abilities had more grey matter in an area at the very front of the prefrontal cortex, known as the anterior prefrontal cortex (PFC). This lies just behind the forehead.
“What is it about this region that gives us this ability?” asks Fleming. “Could the fact that it is more developed in humans mean that we have a fundamentally different self-awareness to animals?”
The other classic way of understanding how the brain works is to look what happens when it is not functioning as it should. Take “blindsight”, a very rare condition usually caused by brain injury. Those affected act as though they are, to all intents and purposes, sightless. But careful testing reveals they can take in some visual information about the world at an unconscious level. When asked to guess what object is in front of them, for instance, they do better than if they had just guessed randomly – insisting all the while that they can see nothing.
Blindsight has always been thought to arise from damage to the visual cortex, at the back of the brain, where information from the optic nerves first arrives. Recent brain imaging studies, however, suggest that the damage also affects , the same region highlighted by Fleming. “That’s a pretty big rethink,” says Hakwan Lau at Columbia University in New York City, who led the work.
Such a change of heart would sit better with Fleming’s work, as blindsight is one of the starkest failures of metacognition it is possible to imagine.
Out of control
Less extreme impairments of metacognition may be involved in other more common disorders, such as schizophrenia, which involves delusions and hallucinations. “Schizophrenics have a problem with that very central metacognition; that I know I’m me and I know what I’m doing,” says Janet Metcalfe, also at Columbia University.
She has studied the using a simple cursor-based computer game. At first the schizophrenia patients were as good at judging how well they performed as the group of healthy control subjects. But when Metcalfe started secretly moving the cursor herself, the control group quickly recognised something strange was going on. People in the schizophrenia group, on the other hand, failed to realise that they were no longer completely responsible for the cursor’s movements.
Some people with schizophrenia come to believe that others are controlling their behaviour, claiming, for instance, that a microchip has been implanted inside their head. “If you don’t know you’re controlling your own behaviour, you could be open to that kind of symptom,” says Metcalfe.
As well as potentially helping people with schizophrenia, better understanding of metacognition could improve teaching in schools. Metcalfe has found that children aged from about 7 to 11 are capable of making good metacognitive judgements about how well they know a subject, but may fail to make use of that knowledge.
For instance, such children prefer to continue spending time on a subject they already know rather than moving on. “It would be interesting to try to teach teachers how to use metacognition effectively,” says Metcalfe.
It may be possible to improve people’s metacognitive abilities, by giving them feedback after the kind of computer tasks used by Fleming. Metcalfe hopes this will help people with schizophrenia. But suppose the rest of us did the same kind of training. Would that give us a supercharged super-consciousness? “If you define consciousness as what it’s like to see the colour red, then it’s not going to change that,” says Fleming. “But if it’s being able to accurately reflect on what you see, or whether you just made a good decision, then training could give it a boost.”
This article appeared in print under the headline “Higher levels”
