The potential power of experience in communications of expert consensus levels

Understanding the scientific consensus on anthropogenic climate change has been dubbed a ‘gateway belief’ to engaging people in sustainable behaviour. We consider the question of how the impact of a consensus communication can be maximised. Firstly, the credibility of the communicator should be maximised. One way of achieving this is to present the opinions of a sample of scientists directly to individuals. The decision-making literature suggests that such a technique will confer an additional advantage over standard descriptions of consensus (e.g. ‘97% of scientists agree’). In decision-making research, low probabilities tend to be overweighted when probabilities are described, but underweighted when probability information is experienced. Consequently, statements of high consensus may lead to an overweighting of the dissensus, a phenomenon that may be reversed were the consensus to be ‘experienced.’ We obtain some positive support for our proposal that consensus is best ‘experienced’ in one of two experiments. We suggest that the lack of stronger positive support could relate to ceiling effects for the topics studied and propose that investigation of effective methods for ‘experiencing’ the consensus is a fruitful area for future research.