“If our brains were always updating in real-time, the world would be a jittery place with constant fluctuations in shadow, light and movement, and we’d feel like we were hallucinating all the time,” said study senior author David Whitney, a UC Berkeley professor of psychology, neuroscience and vision science.

Instead, “our brain is like a time machine. It keeps sending us back in time. It’s like we have an app that consolidates our visual input every 15 seconds into one impression so we can handle everyday life,” said study lead author Mauro Manassi, an assistant professor of psychology at the Scotland’s University of Aberdeen and former postdoctoral fellow in Whitney’s lab at UC Berkeley.

For the study, Manassi and Whitney looked at the mechanism behind change blindness, in which we don’t notice subtle changes that occur over time, such as the difference between actors and their stunt doubles, or movie bloopers.

They recruited some 100 study participants through Amazon Mechanical Turk’s crowdsourcing platform and had them view close-ups of faces morphing according to ages or gender in 30-second time-lapse videos.