Are two heads better than one when it comes to solving problems and reaching decisions? Yes, says a team of EU-funded researchers from Denmark and the UK after discovering that two heads are indeed better but only when both partners are equally competent and could agree after discussing the problem soundly. The work, published in the journal Science, is an outcome of the MINDBRIDGE ('Measuring consciousness - bridging the mind-brain gap') project, which received EUR 2.14 million under the ' New and emerging science and technology' (NEST) Activity of the EU's Sixth Framework Programme (FP6) to develop strategies and methodologies to bridge the gap between subjective experience and objective observation of neural phenomena. In their study, Professor Chris Frith of the UK's Wellcome Trust Centre for Neuroimaging at University College London (UCL) and Professor Niels Bohr of Aarhus University in Denmark, along with their colleagues, investigated whether two people have the ability to combine their sensory information. Their results show that human beings have a knack for combining information from various sensory sources in order to make a decision - one that is a great deal more solid than one that comes from either source on its own. 'When we are trying to solve problems, we usually put out heads together in teams, calling on each other's opinions,' explained UCL's Dr Bahador Bahrami, lead author of the study. '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.' In a first experiment, the researchers called on the study's participants, who worked in pairs, to detect a very weak signal delivered via computer screen. If the volunteers disagreed about when the signal occurred, then they conferred until they reached a joint decision. Based on the experiment's findings, joint decisions are much better than decisions made by the 'better-performing' person. So in a nutshell, two heads are indeed better than one. The team also carried out another two experiments which indicated that the stronger result depends on the partners' capacity to speak to one another. Just telling a person they're right is not good enough, the researchers said. The fourth and final experiment found the opposite, however. The participants, again working in pairs, performed the same task but one of the volunteers did not know that they were secretly made 'incompetent' by being shown a noisy image whose signal was not easy to detect. In this particular case, two heads are not better than one. The researchers found that the participants would have had better results had they paid no attention to what the 'incompetent' partner said. 'When two people working together can discuss their disagreements, two heads can be better than one,' Professor Frith said. '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. Joint decisions don't work when a member of the team is incompetent, but doesn't know it. '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.'