New research finds viewing a video of an ambiguous incident does not necessarily lead to more objective assessments of guilt and innocence.

“Let’s look at the tape” has become our go-to response for determining the truth of an ambiguous situation. With video recorders tracking everything from baseball games to riots, it seems natural to take a second, closer look before determining precisely what happened, and who was at fault.

However, new research suggests this process doesn’t necessarily lend itself to impartial fact-finding. On the contrary, it finds close viewing of videos often leads people to conclusions that confirm their biases.

“The more intently people look at evidence presented, the less they may see it in similar, objective ways,” concludes a research team led by New York University psychologist Emily Balcetis. Its findings are published in the Journal of Experimental Psychology: General.

The researchers describe three experiments that provide evidence for their rather disheartening assertions. The first featured 152 New York University undergraduates and community members, who began by filling out a questionnaire designed to determine the degree to which they identify with police officers.

"One might think that the more closely you look at videotape, the more likely you are to view its contents objectively. But that is not the case. In fact, the more you look, the more you find evidence that confirms your assumptions about a social group, in this case police."

They then “watched a muted 45-second video depicting an actual altercation between a police officer and a civilian, in which officer wrongdoing was ambiguous.” While doing so, their eye movements were unobtrusively tracked, so that the researchers could record exactly what they were focusing on at any given moment.

Afterwards, “participants reported the degree to which they interpreted the officer’s actions to be incriminating,” and indicated the degree to which they felt he should be reprimanded or punished.

Balcetis and her colleagues found the participants who were able to rise above their prejudices were also those whose gaze wandered around the screen, rather than fixating on the police officer. In contrast, those who kept their focus on the policeman showed clear signs of bias: Participants who did not strongly identify with him advocated harsher punishment, while those who strongly identified with him argued for a lighter reprimand.

The same results were found for a second, similarly structured experiment, in which 139 participants watched a different video showing a policeman engaging in ambiguous behavior. In both cases, the researchers write, “Identification polarized punishment decisions only among participants who focused more visual attention on the officer.”

This is a disturbing dynamic. If you feel threatened by a member of a group you dislike or distrust—be it police officers, racial minorities, or anyone else—you have a strong incentive to keep your eye on such a person in a threatening situation. This research suggests doing so leads to a skewed view of the actual events, which in turn makes you more likely to place blame on the person you were suspicious about in the first place.

“One might think that the more closely you look at videotape, the more likely you are to view its contents objectively,” Balcetis said in a statement accompanying the study. “But that is not the case. In fact, the more you look, the more you find evidence that confirms your assumptions about a social group, in this case police.”

There’s an obvious lesson here for jurors assessing videotaped evidence in a court case: Watch such footage repeatedly, focusing on all of the people involved, not just the alleged perpetrator. For the rest of us, the takeaway is more basic: Technology is not likely to help us overcome our biases.