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.