Rewatching Videos of People Shifts How We Judge Them, Study Indicates

Rewatching recorded behavior, whether on a Tik-Tok video or police body-camera footage, makes even the most spontaneous actions seem more rehearsed or deliberate, new research shows. The findings, published in Psychological Science, raise new questions about the judgments people make about everything from TV advertisements to courtroom evidence. 

“In the modern world, recording, sharing, and replaying is easier and more common than ever before, underscoring the importance of understanding how these behaviors impact perceiver judgments,” researchers led by Kristin Donnelly of the University of Chicago Booth School of Business reported.  

Donnelly’s coauthors are William H. Ryan and Leif D. Nelson of the University of California, Berkeley. The researchers documented what they call a “replay bias,” in which people intuit the actions in a video recording as reenactments rather than just playback of a single incident.

“Our findings suggest that rewatching a recorded event gives the viewer an intuitive impression that the people in the video are repeating their actions or behavior in precisely the same way,” Donnelly told APS. “At least to some extent, viewers may apply their understanding of repetition in the real world to a replay context. In the real world, precisely repeating one’s behavior typically requires lots of bodily control, which often comes with practice or rehearsal.” 

The research spanned nine experiments involving more than 10,000 online participants and used an assortment of video and audio recordings, including audition tapes, commercials, and potential trial evidence.  

Initial experiments showed that behavior appeared more rehearsed and less spontaneous when watched multiple times. Replay also made “first-time” emotional reactions, which are only genuine when spontaneous, seem less authentic. In one experiment, participants watched commercials purporting to show “real people,” not actors. The clips featured surprised reactions from customers discovering that an ostensibly high-end product they were trying was actually from a low-cost brand. Study participants were randomly assigned to rate whether individuals in the videos were actors or actual consumers. When they saw a commercial three times rather than once, participants thought the people it featured were more likely to be actors and less likely to be “real people.”  

In another study, participants watched a 3-s clip from the reality TV show Cops, in which a police officer tells a woman named Dalia Dippolito that her husband has been killed. The woman reacts with anguish, sobbing and clutching the officer.  

Participants were not told that police were lying. Her husband Michael had survived an attempt on his life and the police suspected Dalia of hiring the hitman who tried to kill him.*  

The participants were randomly assigned to watch the clip either once or three times, then reported whether they thought Dalia was guilty or innocent. They were more likely to deem her guilty if they watched the video three times rather than once. 

The results suggest that replays from body cameras, surveillance footage, and cellphone recordings—all increasingly used as key evidence in criminal trials—could impact judgments of a criminal suspect’s culpability, the authors noted.  

The researchers call for studies on how these effects might arise in other contexts and cultures. But the findings indicate effects that stretch across a variety of domains. People may view a public figure’s recorded faux pas, for instance, as a calculated offense if they watch it replayed. Advertisers may want to limit consumers’ exposure to commercials that feature the reactions of “real people,” as repeated viewings may make the behaviors seem inauthentic. Lawyers should consider whether replaying a video clip of a defendant’s behavior in court could change jurors’ perceptions of guilt.  

“To understand how a video will influence its viewer,” the authors wrote, “one will need to consider not only whether it is viewed, but whether it is viewed again.” 

* Dalia Dippolito was eventually charged with attempted murder and is now in prison for her crime. Participants who had reported being aware of the case were excluded from that study.  

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Donnelly, K., Ryan, W. H., & Nelson, L. D. (2024). Once and again: Repeated viewing affects judgments of spontaneity and preparation. Psychological Science. 

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