Who dunnit?

Stereotypes can cause witnesses to ‘see’ events that never happened

By Mark DiPietro

Researchers at Puget Sound are confirming a long-held suspicion that cultural and racial stereotypes produce false eyewitness memories.

“It’s easy to get people to believe they saw something they expected to see,” says Mark Reinitz, an associate professor of psychology and coauthor of a series of new studies on how stereotyping affects memory. “Our study is the first to show you can produce false memories of someone doing unsavory things based on stereotypes alone.”

Reinitz and Carolyn Weisz, chair of the psychology department, showed 72 participants a series of slides of a man entering a fast-food restaurant and buying a burger. Subsequent slides show the man unwrapping the burger, followed by a slide of the wrapper littering the ground where the man was standing. A final slide shows the man walking away.

Here’s the catch: For the study, one group of subjects was shown a poorly dressed man who appeared to be homeless, while a second group was shown a well-dressed professional. Neither group actually saw either man littering.

Forty-eight hours later, the participants returned and viewed a missing slide that showed the man throwing the wrapper on the ground.

Those who viewed slides of the homeless man were much more likely to falsely remember having seen the “throwing-the-wrapper” picture in the original images than were those who viewed the well-dressed professional. The latter group was more likely convinced the littering slide was a new addition.

“Every picture in each set of slides was identical, except for the man’s clothes,” notes Reinitz.

Reinitz and Weisz presented their findings to the biennial meeting of the Society for Applied Research in Memory and Cognition in early July.

Other studies have shown it’s possible to plant a false memory by inferring a scenario—that is, showing the wrapper on the ground causes the participants to make a “causal inference” that the man littered. However, stereotyping has until now been a sketchy area for psychological researchers.

“Our basic finding is that causal inference is very weak when you don’t expect someone to do it,” says Reinitz. “People are less likely to believe they saw the well-dressed guy littering without actually seeing the slide of him littering.”

Reinitz and Weisz plan more experiments to test other stereotypes and other crimes.