14 DAY TRIAL // Two judgments can be better than one, but only if you have the right partner, a new study carried out by neuroscientists from University College London and Aarhus University, Denmark suggests.
The study tested volunteers that came into the lab in pairs, and concluded that two heads are better than one but only if both partners are equally competent and able to freely discuss their disagreements.
Professor Chris Frith of the Wellcome Trust Center for Neuroimaging at UCL and Niels Bohr, Professor in the University of Aarhus, asked the subjects to detect a very weak signal that was shown on a computer screen, and if they did not agree on when the signal occurred, they could discuss together until coming to the same conclusion.
The first experiment showed that the joint decisions were even better than the individual one, made by the better-performing one in the duo.
The next two experiments showed that this improvement depended on the ability of the partners of discussing together, however the fourth experiment shoved that sometimes two heads are worse than one.
A same task was given to pairs of volunteers, but one of each pair was sometimes made incompetent by being shown a noisy image with a more difficult to see signal, and this resulted in joint decisions worse than that of the better-performing partner.
Professor Frith explains: “When two people working together can discuss their disagreements, two heads can be better than one, but when one person is working with flawed information -- or perhaps is less able at their job -- then this can have a very negative effect on the outcome.
“Being able to work together successfully requires that we know how competent we are [as] joint decisions don't work when a member of the team is incompetent, but doesn't know it.”
This theory can be applied in real life, like for example when driving, we use our vision as well as our sound to appreciate the speed of an approaching car.
But the results are not the same when putting two people to work together.
“When we are trying to solve problems, we usually put our heads together in teams, calling on each other's opinions," said Dr Bahador Bahrami, lead author of the study from UCL.
“For our study, we wanted to see if two people could combine information from each other in a difficult judgment task and how much this would improve their performance.
“We know all too well about the catastrophic consequences of consulting 'evidence' of unknown reliability on problems as diverse as the existence of weapons of mass destruction and the possibility of risk free investments.”
The study was funded by the European Union MindBridge project, the Danish National Research Foundation, the Danish Research Council for Culture and Communication, the Gatsby Charitable Foundation and the Wellcome Trust.
It was published in the journal Science.