Binocular fusion enhances the efficiency of spot-the-difference gameplay

PLoS One. 2021 Jul 20;16(7):e0254715. doi: 10.1371/journal.pone.0254715. eCollection 2021.

Abstract

Spot-the-difference, the popular childhood game and a prototypical change blindness task, involves identification of differences in local features of two otherwise identical scenes using an eye scanning and matching strategy. Through binocular fusion of the companion scenes, the game becomes a visual search task, wherein players can simply scan the cyclopean percept for local features that may distinctly stand-out due to binocular rivalry/lustre. Here, we had a total of 100 visually normal adult (18-28 years of age) volunteers play this game in the traditional non-fusion mode and after cross-fusion of the companion images using a hand-held mirror stereoscope. The results demonstrate that the fusion mode significantly speeds up gameplay and reduces errors, relative to the non-fusion mode, for a range of target sizes, contrasts, and chromaticity tested (all, p<0.001). Amongst the three types of local feature differences available in these images (polarity difference, presence/absence of a local feature difference and shape difference in a local feature difference), features containing polarity difference was identified as first in ~60-70% of instances in both modes of gameplay (p<0.01), with this proportion being larger in the fusion than in the non-fusion mode. The binocular fusion advantage is lost when the lustre cue is purposefully weakened through alterations in target luminance polarity. The spot-the-difference game may thus be cheated using binocular fusion and the differences readily identified through a vivid experience of binocular rivalry/lustre.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Female
  • Humans
  • Male
  • Photic Stimulation
  • Vision Disparity / physiology*
  • Vision, Binocular / physiology*
  • Visual Perception / physiology*
  • Volunteers
  • Young Adult

Grants and funding

This study was supported by the Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation. The funders of this study had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The funders of this study supported the salary of AH and SRB. The author(s) have no proprietary or commercial interest in any materials discussed in this article.