Abstract
Evidence indicates that both perceived size SI and retinal size O are involved in both the relative and familiar size CUE to relative depth. There is also evidence to indicate that the familiar size cue cannot be subsumed under the relative size cue.But both types of size cues can be included under the con- cept of perceived size per unit of retinal size(SI/O~It is as- serted that the perceived depth between objects, as determined by the size cue. is a function of the value of S,/O associlted with each of the objects. Evidence relevant to spedivying the relation between values of SI/0 and perceived depth is ev~l- uated with respect *. methodological problems involved inthe use of comparison fields.