We do not notice many tasks that our brains perform, whereas we are completely aware of others. But it is sometimes hard for neuroscientists to determine when we are conscious of our actions. Now a group of British researchers is betting that betting can be used to study consciousness.

Navindra Persaud, Peter McLeod and Alan Cowey of the University of Oxford were interested in situations in which people can show high levels of cognitive performance with no apparent awareness. In one experiment, they studied a person known as GY, who, because of damage to his visual cortex, reports no vision in his right eye. But GY has a strange ability known as blindsight: he can guess with reasonable accuracy whether or not a symbol is shown to that eye, even though he reports no awareness of seeing it. The question has remained whether at some level he is conscious of his performance.

The researchers asked GY to make one of two wagers after each guess: £1 or half that amount. If he guessed correctly, the sum was added to his winnings. If he guessed incorrectly, the money was subtracted. In other words, GY had a financial incentive to be conscious of when he guessed correctly and bet high on those occasions. But although GY guessed correctly 70 percent of the time, he chose a high wager only about half of the time, almost at random.

The researchers point out that the dissociation between cognitive performance and betting performance is surprising because, in a way, the high and low wagers are a decision very much like GY saying “yes” or “no” to seeing an object. They argue this disconnect between GY's blindsight performance and his betting success suggests that placing a bet is a special type of decision. Successful gambling appears to require consciousness of one's performance.

Persaud and his colleagues have already used this link to measure awareness in healthy volunteers. “We hope to combine [the wager test] with imaging and recording methods,” he says. That may make it possible to finally identify the elusive neural circuitry that encodes consciousness.