Subliminal Stimuli Generated in Films through Successive Frames: A Quantitative Assessment

Although numerous theoretical references have been made to subliminal stimuli in filmmaking, no quantitative studies to date have sought to specify their temporal limits. Since the 1920s, several filmmakers have aimed to elicit an emotional impact on the viewer through the inclusion of isolated frames, which supposes the minimum possible temporal extension in films. Through two experiments, this study analysed the threshold between subliminal and supraliminal stimuli in films containing potential subliminal stimuli comprising one to four frames, played at frame rates of 25, 30, and 60 frames per second. The first experiment involved asking participants to view a film excerpt, including these stimuli, and then answer a survey. The second required participants to identify potentially subliminal stimuli whilst viewing a film clip. The stimuli analysed could not be defined as subliminal for 100% of viewers for any number of frames per frame rate, but were predominantly unidentified for one-frame stimuli in films played at 24 or 30 frames per second, and one- to three-frame stimuli in films played at 60 frames per second. Furthermore, three- and four-frame stimuli at 24 and 30 frames per second were found to be supraliminal, whilst the results for two-frame stimuli played at 24 or 30 and four-frame stimuli played at 60 frames per second were inconclusive. Future research is needed to analyse the effect of the nature of the image used as a stimulus and its location within a shot or in a cut between shots.