Hill H, Johnston A, 2007, "The hollow-face illusion: Object-specific knowledge, general assumptions or properties of the stimulus?" Perception 36(2) 199 – 223
Download citation data in RIS format
The hollow-face illusion: Object-specific knowledge, general assumptions or properties of the stimulus?
Harold Hill, Alan Johnston
Received 23 September 2005, in revised form 22 March 2006; published online 31 January 2007
Abstract. The hollow-face illusion, in which a mask appears as a convex face, is a powerful example of binocular depth inversion occurring with a real object under a wide range of viewing conditions. Explanations of the illusion are reviewed and six experiments reported. In experiment 1 the detrimental effect of figural inversion, evidence for the importance of familiarity, was found for other oriented objects. The inversion effect held for masks lit from the side (experiment 2). The illusion was stronger for a mask rotated by 90° lit from its forehead than from its chin, suggesting that familiar patterns of shading enhance the illusion (experiment 2). There were no effects of light source visibility or any left/right asymmetry (experiment 3). In experiments 4 – 6 we used a ‘virtual’ hollow face, with illusion strength quantified by the proportion of noise texture needed to eliminate the illusion. Adding characteristic surface colour enhanced the illusion, consistent with the familiar face pigmentation outweighing additional bottom – up cues (experiment 4). There was no difference between perspective and orthographic projection. Photographic negation reduced, but did not eliminate, the illusion, suggesting shading is important but not essential (experiment 5). Absolute depth was not critical, although a shallower mask was given less extreme convexity ratings (experiment 6). We argue that the illusion arises owing to a convexity preference when the raw data have ambiguous interpretations. However, using a familiar object with typical orientation, shading, and pigmentation greatly enhances the effect.
This article has supplementary online material: Additional graphic material
Full-text PDF size: 580 Kb
References 66 references, 29 with DOI links ()
Your computer (IP address: 22.214.171.124) has not been recognised as being on a network authorised to view the full text or references of this article. If you are a member of a university library that has a subscription to the journal, please contact your serials librarian (subscriptions information).