People are more racist when their hearts beat faster, a new study suggests.
Scientists have already shown that when the heart beats it sends a signal to the brain that heightens our response to fear. They have also found that when people are shown a man carrying an object they are more likely to wrongly believe it is a gun if it is associated with a black man rather than a white man.
A new paper, published in the journal Nature Communications, looked at how these factors interacted with each other.
People were shown images of men holding either guns or mobile phones, timed to coincide with heartbeats or in between, and then asked to judge which was a gun. If the image of a black man was shown on a heartbeat, rather than in between, the study participants were significantly more likely to misidentify a phone as a gun.
The study implies that people may make worse decisions when stressed. This could help to explain why in the US black people are more than twice as likely to be unarmed when killed by the police than white people.
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Sarah Garfinkel, a co-author of the study from the University of Sussex, said: “A faster, stronger heartbeat gives greater potential to tap into these signals, resulting in more racist behaviour.”