In 2015, a study published in the journal Science shook up the scientific community. Researchers tried to reproduce the results of 100 published psychological studies, but were unable to do so two-thirds of the time. Known as the “replication crisis,” this phenomenon has been observed in other scientific fields. But the reasons behind the issue are challenging to tease out. As Richard Harris reports for NPR, one often-ignored influencing factor might surprise you: the gender of the scientists involved.
As part of a review published in Science Advances, a team of three researchers from Uppsala University, in Sweden, looked through a number of past studies and found examples of experiments that were impacted by whether the testers were male or female—“many, many” examples, Harris writes. For instance, children tend to perform better on IQ studies if the tester is a woman. But when it comes to problem-solving tasks, male testers elicit better results among subjects of both sexes. Male college students have been found to inflate their number of sexual partners when being surveyed by a woman. And in studies measuring pain sensitivity, men have been found to report significantly higher pain thresholds when they are interacting with a female tester.
"If you're testing out a new drug for pain, and you're getting these kinds of great results, you might want to look at [the genders of] who's running the experiment and who's participating in the experiment, because that could explain it more than the drug itself," Colin Chapman, one of the authors of the new study, tells Harris.
The paper puts forth a number of hypotheses that might explain why gender influences experimental findings—particularly when it comes to heterosexual subjects. It is possible that subjects’ responses are shaped by their desire to appear more likable or attractive to someone of the opposite sex. This “psychosocial stress,” as the researchers put it, can be linked to a biological response. One study has shown, for instance, that men tested by female experimenters display higher systolic blood pressure, and vice versa.
“Experimenter gender should have the greatest impact in areas of study where participants are in frequent and close contact with experimenters,” the authors of the paper write. “In addition, experiments implicating characteristics important for mate selection—such as mental acuity, physical prowess, or morality—may be more influenced.”
Gender is likely not the only factor that can sway the results of an experiment. “I imagine race, ethnicity, age, that all of those things could have important effects on how research participants perform in a research study,” Kristina Gupta, assistant professor in women’s, gender, and sexuality studies at Wake Forest, tells Ryan F. Mandelbaum of Gizmodo. But the new study maintains that accounting for the influence of gender—by making it standard practice to report the gender of experimenters in scientific studies—could help scientists’ ability to replicate significant experiments.