BLUR AND CONTRAST AS PICTORIAL DEPTH CUES

Studies have shown that blur can act as a pictorial cue to depth perce ption. But blurring a stimulus reduces its contrast, and studies have also shown that contrast can act as a pictorial cue to depth perceptio n. To determine whether blur and contrast have separate influences on depth perception, each variable was independently manipulated in two e xperiments. Observers reported depth alternations in a simple reversib le figure. Both contrast and blur were found to influence depth percep tion, but blur had its greatest effect at moderate contrasts. When blu rred and sharp stimuli were equated on either Michelson or RMS contras t, blur continued to affect depth perception. Hence blur can act as a depth cue independently of contrast. It is speculated that blur is eff ective as a pictorial cue because of its usual association with other depth cues, particularly in pictures and photographs.