Scientific Thought

Using Pritchard's technique, the frequency and duration of total disappearance of stabilized images were compared using two reporting procedures: i.e., (a) a running commentary and (b) only “off” or “on.” Two target figures were employed: a simple triangle and a five-by-five grid of squares. The incidence and duration of complete disappearance was (a) less with the commentary than with the off-on procedure and (b) less with the grid than with the triangle. Hypotheses to account for the differences are discussed.