Proceedings of the Annual Meeting of the Cognitive Science Society

People do not think in isolation. Whether purchasing a new product on Amazon, deciding what movie to watch, or evaluating scientific evidence, we often rely on aggregated sources of information (e.g., product ratings or reviews) to make decisions. Indeed, the internet has given rise to unprecedented levels of aggregated information, to the extent that it is difficult to imagine anything for which we might not be able to find summary information. In other words, what we know (or think we know) is constrained not just by our own knowledge, but by the knowledge of our community (Sloman & Rabb, 2016). Yet this raises a question: what happens when a community of knowledge is not in agreement? Here, we assess this question by pitting cases of high confidence against cases of high consensus. Results from two experiments show that 1) individuals are sensitive to both confidence and consensus; 2) individuals utilize such information in a predictable but context-dependent manner; and 3) perceptions of confidence and consensus influence judgments and decisions in a substantial way, even when individuals are not aware of the contrast between them. Taken together, the findings suggest that individuals are highly sensitive to variability in aggregated information – rather than merely an average – and that these ‘summary statistics’ of aggregated information have a substantial, reliable impact on decision-making.