Differences in the magnitude of the simultaneous and successive Mueller-Lyer illusions from age twenty to seventy-nine years.

The simultaneous Muller-Lyer illusion, a Type I phenomenon, and the successive Muller-Lyer illusion, a Type II phenomenon, were used to examine differences in perceptual functioning with subjects age 20 to 79 years. A significant main effect of age was found. These results were interpreted as tentative support for the stimulus persistence model.