Visual Activity in Hollywood Film: 1935 to 2005 and Beyond

The structure of Hollywood film has changed in many ways over the last 75 years, and much of that change has served to increase the engagement of viewers' perceptual and cognitive processes. We report a new physical measure for cinema-the visual activity index (VAI)-that reflects one of these changes. This index captures the amount of motion and movement in film. We define whole-film VAI as (1 - median r), reflecting the median correlation of pixels in pairs of near-adjacent frames measured along the entire length of a film or film sequence. Analyses of 150 films show an increase in VAI from 1935 to 2005, with action and adventure films leading the way and with dramas showing little increase. Using these data and those from three more recent high-intensity films, we explore a possible perceptual and cognitive constraint on popular film: VAI as a function of the log of sequence or film duration. We find that many "queasicam" sequences, those shot with an unsteady camera, often exceed our proposed constraint.