“…The rationale for considering relative size as a cue to relative distance is based on the fact that the same object produces a different difference in visual directions at various distances. Its effectiveness has been well documented (e.g., Epstein, 1961;Gogel, Hartman, & Harker, 1957;Hochberg & Hochberg, 1952;Hochberg & McAlister, 1955;Ono, 1966Ono, , 1969, although the relevant variable in those studies was thought to be different retinal image sizes. In other words, whenever 5 has information concerning, or assumes, stimulus identity (i.e., that the stimuli presented are the same stimulus or of constant linear size), variations in the perceived angular size of the stimulus may serve as a relative size cue to relative distance.…”