Maybe going back to check the door is locked is a good idea after all Westend61/Getty

Life is full of decisions, and sometimes it’s difficult to know if you’re making the right one. But a drug that blocks the rush of noradrenaline through your body can boost your confidence, and may also lead to new treatments for schizophrenia and obsessive compulsive disorder.

How much we trust our decisions is governed by the process we use to assess our own behaviour and abilities, known as metacognition. Our judgements shape how we’ll behave in future. For example, if you play Frisbee and you think you played badly, you might be less likely to do it again, says Tobias Hauser at University College London.

Having low confidence in our actions can play a part in mental health conditions. “We see many symptoms associated with poor metacognitive judgement in schizophrenia and OCD,” says Hauser. “In OCD, for instance, people may constantly go and check whether they’ve closed a door. They are poor at judging whether they have done something correctly or not.”


Confidence test

Little is known about the neural underpinnings of metacognition, but it is likely to involve the prefrontal cortex and the hippocampus, two brain areas modulated by the chemicals dopamine and noradrenaline.

To investigate, Hauser and his colleagues asked 40 people to take a drug that blocks dopamine or noradrenaline either before or after a placebo. Another 20 people received two doses of the placebo drug.

Eighty minutes after receiving the second drug, the subjects performed a task in which they had to decide whether the overall motion of a burst of randomly moving dots was directed to the left or right (see below).

Volunteers had to judge whether the overall movement of the dots is towards the left or right Micah Allen, University College London

The difficulty of the task was continuously adjusted, so that the participants got the correct answer about 70 per cent of the time – but the participants didn’t know this. When performing the task, the volunteers were all asked how confident they were in each of their judgements.

Erased information

Comparing the volunteers’ self-assessed confidence with their actual performance revealed the effect of each drug. The drug that reduced noradrenaline boosted metacognitive insight – it made volunteers more aware of their own performance, without affecting the accuracy of their decisions. A person was more likely to say they’d been correct when they were, and to know if they’d been wrong. Neither the drug that blocked dopamine nor the placebo had any effect.

“This study is very intriguing – it’s the first to show that metacognition can be selectively enhanced by drugs in the absence of differences in task performance,” says Steve Fleming, at University College London, who wasn’t involved in the study.

Hauser says noradrenaline is released when there is unexpected uncertainty in the world, such as when we make an incorrect decision. “We think that this burst of noradrenaline when you make an error erases the information about a task that you recently stored in your memory.”

This could mean that a participant who has made an incorrect decision or was struggling to reach a decision may have their system reset, rendering them unable to draw on as much information to later evaluate this decision. “You are no longer able to properly judge how well you did in the task because you’re judging your decision using less evidence,” says Hauser.

Better insight

Blocking noradrenaline seems to allow people to better assess their confidence in an action. The drug, called propranolol, is currently used to treat high blood pressure, but it may also prove useful for treating psychiatric symptoms like some of those seen in OCD and schizophrenia.

It’s possible that some people without conditions like these may also benefit from cutting the amount of noradrenaline in their system. “There’s quite some variability in metacognition,” says Hauser. “It is likely to have an effect in real life decision-making. Whether you trust what you’re writing, whether you’re confident in what you’re saying – all our actions involve metacognition.”

“Good metacognition is useful for a range of reasons – being aware of our skills and abilities is important for guiding learning and collaborating with others,” says Fleming. He says it would be interesting to see if the same drug might improve our insight into our performance in other aspects of cognition, such as memory.

Journal reference: eLife, DOI: 10.7554/eLife.24901