Observer Bias

Definition

When the researcher's expectations influence the data.

Example

In a 1963 study conducted by Robert Rosenthal and Kermit Fode, students were given rats that were either identified as "maze bright" or "maze dull," and asked to run experiments with the rats. There were actually no differences in the rats. However, the students' identified the performance of the "maze bright" rats as being superior to the performance of the ''maze dull" rats. The results they recorded were influenced entirely by their expectations, not by the actual performance of the rats.

Why It Matters

Observer bias reminds us that researchers are human, too. Even without meaning to, their expectations can shape what they notice or how they interpret what they see. Being aware of observer bias helps researchers design studies that are more fair, accurate, and trustworthy.

Related Terms

• social desirability bias