Nonetheless, film did not start out well meshed with human perceptual and cognitive systems. Instead, it has evolved slowly over the last 120 years. Early in the 20th century, frame presentation rates were increased to make the flicker of the successive images less aversive. At the same time cuts, dissolves, and fades were used to denote shots within the same scene, across scenes, and across larger filmsegments (acts), respectively. But later the use of dissolves and fades as visual cues to filmstructure was found to be largely unnecessary. Since the 1970s almost 99% of all transitions between shots in popular film are now cuts (Cutting et al.
