The tendency to be subjective about people and events, causing biased information to be collected in a study or biased interpretation of a study’s results.
Perception bias is the tendency to be somewhat subjective about the gathering and interpretation of healthcare research and information.
There is evidence that although people believe they are making impartial judgements, in fact, they are influenced by perception biases unconsciously.
There are several subtypes:
An example is reporting of alcohol intake among young adults as drinking is influenced by perceptions of how much their peers drink. These perceptions are often wrong and overestimate drinking norms (Foxcroft et al. 2015).
In a study of students reporting fruit and vegetable consumption (Nix & Wengreen 2017), the investigators measured intake by self-report before and after receiving different information messages. Students in the low normative group (receiving the message they were in the lowest 20th percentile of intake) reported a half-cupful increase in fruit and vegetable intake and a one-cup increase in perception of peers’ consumption, while there were no significant differences in the other groups (highest 20th percentile or no message).
Studies using objective measures are less likely to suffer from perception bias. Studies which rely on self-reported information, or observations that could be influenced by perception biases, should be interpreted with additional caution.
Catalogue of Bias Collaboration, Spencer EA, Brassey JR. Perception bias. In: Catalogue Of Bias 2017. https://www.catalogofbias.org/biases/perception-bias