Deepfake videos that feature digital manipulations of people’s facial expressions and voices can also depict realistic heartbeats, making them even harder to spot.

“We now know that just because a person in a video has a measurable pulse, it doesn’t mean that we can assume they are real,” says Hany Farid at the University of California, Berkeley, who was not involved in the research.

This development comes as deepfakes that have been digitally altered or generated…