Alex Pouget, associate professor of brain and cognitive sciences at the University of Rochester, has shown people make optimal decisions, but only when their unconscious brain makes the choice.

"A lot of the early work in this field was on conscious decision making, but most of the decisions you make aren't based on conscious reasoning," Pouget said in a statement.

The researchers used a series of dots on a computer screen with most of dots moving in random directions. A controlled number of dots are purposely moving uniformly in the same direction, and the test subject has to say whether he or she believes the dots are moving to the left or right. The longer the subject watches the dots, the more evidence he or she accumulates.

The study, published in the journal Neuron, said the subjects were never aware of the complex computations going on, but simply "realized" suddenly that the dots were moving in one direction or another.

Pouget said this decision-making system based on the mathematical likelihood of potential events has several advantages, but most importantly it allows people to reach a reasonable decision in a reasonable amount of time.