Where do the eyes really go in the hollow-face illusion?

PLoS One. 2012;7(9):e44706. doi: 10.1371/journal.pone.0044706. Epub 2012 Sep 4.

Abstract

The hollow-face illusion refers to the finding that people typically perceive a concave (hollow) mask as being convex, despite the presence of binocular disparity cues that indicate the contrary. Unlike other illusions of depth, recent research has suggested that the eyes tend to converge at perceived, rather than actual, depths. However, technical and methodological limitations prevented one from knowing whether disparity cues may still have influenced vergence. In the current study, we presented participants with virtual normal or hollow masks and asked them to fixate the tip of the face's nose until they had indicated whether they perceived it as pointing towards or away from them. The results showed that the direction of vergence was indeed determined by perceived depth, although vergence responses were both somewhat delayed and of smaller amplitude (by a factor of about 0.5) for concave than convex masks. These findings demonstrate how perceived depth can override disparity cues when it comes to vergence, albeit not entirely.

MeSH terms

  • Adult
  • Cues
  • Depth Perception / physiology*
  • Face / anatomy & histology
  • Form Perception / physiology*
  • Humans
  • Optical Illusions / physiology*
  • Pattern Recognition, Visual / physiology*
  • Photic Stimulation
  • Vision Disparity / physiology
  • Vision, Binocular / physiology

Grants and funding

There was no third-party funding. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.