People often learn about categories, particularly social
categories, based on biased information. Unless people are
able to correct for this, they may develop biased beliefs and
inferences about these categories. The current research
examines if potentially biased information about social groups
makes groups appear more homogeneous, and makes people
more confident in their inferences about group members. Two
sources of biases are considered: due to lacking first-hand
experience with a group, or due to having second-hand
information from the media or other people. Both sources
made groups appear more homogeneous, suggesting that
information biases were present and not corrected for.
However, only second-hand knowledge led to greater
confidence about group members, because, when people
lacked first-hand knowledge, their uncertainty about the
group average counteracted this effect. This highlights the
importance of understanding biases present in people’s
information, and corrective processes that may allow people
to continue to make unbiased inferences.