How film editing influences our perception of time

Filmmakers have long used editing techniques to influence the viewing experience. The 'Kuleshov effect' is a classic example. In the 1920s, Russian filmmaker Lev Kuleshov found that by varying the content of an image that followed one of a character's face, he could alter viewers' inferences about what was going on in that character's mind. Now a team led by Klara Kovarski at the Hôpital Fondation Rothschild in France argues that editing techniques can also influence viewers' perceptions of the passage of time.

In work published in Scientific Reports, the team considered two types of editing: continuity editing and action discontinuity editing. The first type aims to maintain a sense of flow in the narrative. For example, a shot of a man standing at a window might cut to an exterior shot of the same window. In the second, the content of the two scenes is completely different. A shot of a man standing a window might cut to a dog running on a beach, for instance; this tells the viewer that the action has shifted.

Kovarski's team ran an initial online study on 90 participants. They each watched 45 brief excerpts, which varied slightly in length, from the movie La Ballon Rouge. One third of these excerpts contained a single cut designed to maintain continuity, one third featured a single discontinuous cut, and the rest did not contain any cuts. After viewing each video, the participant used a sliding scale to estimate its duration.

In a subsequent lab-based study, 60 participants watched the same sequences. But in this study, after each video, a black square appeared on the screen. When the participant decided that the square had been present for the same length of time as the video, they hit a key.

Overall, the results from the two studies showed that excerpts that featured either type of cut were judged to be longer than those without cuts, but sequences with cuts that maintained continuity were judged to be the longest of all.

On the surface, this might seem surprising. Discontinuity cuts tend to signal a transition between scenes or events, and you might expect that clips with more events would be perceived as longer.

But this wasn't the case. Instead, the researchers argue that because discontinuity cuts clearly signal a change in scene, they require less cognitive processing than continuity cuts. With a continuity cut, the viewer's brain has to work out that although the viewing angle or setting has changed, the same narrative is continuing. If additional processing makes time seem to pass more slowly, this might explain the results.

Earlier work has hinted that continuity cuts might undergo greater processing: one study found that this kind of edit goes unnoticed on a conscious level by viewers between a quarter and a third of the time, a phenomenon known as 'edit blindness'. A discontinuity cut, though, signals a clear end to one event and the start of another.

Clearly, more work is needed to explore the factors that influence our perceptions of the passage of time not just in films , but in life too. Indeed, the researchers write: "This study contributes to the emerging field of psycho-cinematics which could ultimately develop the dialog between arts and science."