Scientific insights are only as good as the methods used by scientists. Much of our work is thus motivated by an interest in critically evaluating and improving these methods.

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We are particularly interested in evaluating the extent to which peoples’ beliefs bias their responses in psychology research. For example, earlier research by our team suggested that posed facial expressions can impact peoples’ emotions (e.g., that smiling can make people feel happy). However, we wondered if such effects were merely driven by participants’ beliefs (e.g., placebo effects). Our results suggested they weren’t. Participants reported feeling happier after posing happy expressions and angrier after posing angry expressions – even when they (a) personally believed the effects were not real, or (b) were told we sought to disprove these effects. Nonetheless, beliefs reliably changed the intensity of these effects, raising broader concerns about how such beliefs might create biases in psychology research.

An in-progress meta-analysis of nearly 200 experimental tests suggests that the effects of participants’ beliefs can be just as powerful as the phenomena psychologists seek to understand in their research. More troublingly, participants’ beliefs tend to bias their responses in unpredictable ways that are currently difficult to explain. Thus, we are now working to better understand how these effects work via large cross-cultural experiments and studies.