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Double Vision as a Pictorial Depth Cue

This paper is the first published study on how the inclusion of ‘double vision’ or ‘double images’ can enhance perceived depth in pictures. It is one aspect of Pepperell’s long-standing interest in fusing art practice and scientific investigation in order to understand the nature of human perception and how art can contribute to that understanding.

‘Double vision’ or diplopia occurs when objects are seen outside the normal area of binocular fusion. The first artist to record his own double vision experiences was Evan Walters (1893-1951) and his work and ideas are introduced in the paper. In many paintings made in the middle and end of his career he included not only doubled images in the foreground and background of his subjects but also other subjective effects of visual perception such as peripheral indistinctness. Walters’ claim, made in published articles and an unpublished manuscript, that inclusion of double images in paintings could enhance depth perception had never been scientifically tested, and has received virtually no attention from art historians.

This study was carried out in collaboration with a psychology graduate from University of Bamberg, Germany, and used non-figurative stimuli to measure perceived image depth in a number of conditions. We were able to show for the first time that the inclusion of double images can enhance perceived depth in pictures. This is significant as double images are not listed among the so-called ‘monocular depth cues’ in any of the major vision science textbooks. Therefore, it is potentially a major contribution to knowledge about the pictorial representation of visual perception. This could have important implications in fields such as computer graphics, medical imaging, and virtual reality simulation. In addition, it demonstrates the value and originality of the long-neglected work of Evan Walters.