Ways of Viewing Pictorial Plasticity.

Maarten W A Wijntjes

doi:10.1177/2041669517699220

Abstract

The plastic effect is historically used to denote various forms of stereopsis. The vivid impression of depth often associated with binocular stereopsis can also be achieved in other ways, for example, using a synopter. Accounts of this go back over a hundred years. These ways of viewing all aim to diminish sensorial evidence that the picture is physically flat. Although various viewing modes have been proposed in the literature, their effects have never been compared. In the current study, we compared three viewing modes: monocular blur, synoptic viewing, and free viewing (using a placebo synopter). By designing a physical embodiment that was indistinguishable for the three experimental conditions, we kept observers naïve with respect to the differences between them; 197 observers participated in an experiment where the three viewing modes were compared by performing a rating task. Results indicate that synoptic viewing causes the largest plastic effect. Monocular blur scores lower than synoptic viewing but is still rated significantly higher than the baseline conditions. The results strengthen the idea that synoptic viewing is not due to a placebo effect. Furthermore, monocular blur has been verified for the first time as a way of experiencing the plastic effect, although the effect is smaller than synoptic viewing. We discuss the results with respect to the theoretical basis for the plastic effect. We show that current theories are not described with sufficient details to explain the differences we found.

Highlights

The term stereopsis is often associated with the perception of depth based on binocular disparities
We found that both monocular blur and synoptic viewing induced the plastic effect in comparison with the baseline condition of normal binocular viewing
We can conclude that previous findings (e.g., Wijntjes et al, 2016) cannot be attributed to a placebo effect and that the hitherto neglected viewing mode of monocular blur enhances the impression of pictorial depth as predicted (Ames, 1925; Schlosberg, 1941)

Summary

Introduction

The term stereopsis is often associated with the perception of depth based on binocular disparities It has recently been argued (Vishwanath & Hibbard, 2013) that the subjective impression evoked by stereo pictures very much resembles the depth impression of monocular aperture viewing. This paradoxical (Claparede, 1904; Koenderink, van Doorn, & Kappers, 1994) stereoscopic impression had been predicted before (Ames, 1925; Ebbinghaus, 1902) but was never directly and qualitatively compared with stereoscopic picture viewing.

Methods

Results

Conclusion