Concave and Convex Phases in Ambiguous Figures Showing Colour Shifts. Mach's Figure and the Ambegujas Phenomenon

Abstract

Two ambiguous figures (Mach's book-figure and the AMBEGUJAS phenomenon) have been studied. They show colour shifts synchronised with the shifts of their alternative phases. The perceived concave phase appeared to have chromatic surface colour, but the perceived convex phase can appear to be in coloured illumination and shadow (film colour). The two perceived reversible shapes of the Mach figure (the book and the tent) and the three perceived alternative shapes of the Mondrians used in the AMBEGUJAS phenomenon (a roof, a ceiling, and a tile) all can appear to have chromatic surface colours in their concave phases but appear to have coloured illumination and shadow in their convex phases.

Perspectival Reversals of a Solid: A Phenomenal Description

“…It is possible that although in the present experiment efforts were made to ensure uniformity of illumination, these efforts were not fully successful and that the lack of uniformity of illumination is responsible for reversals of both stimuli. Indirect support for this interpretation is provided by Nozawa (1999) and Bergström and Gustafsson (2011). If so, then whilst all reversals involve concentration of attention, the reversals of 3-D Mach's Book derive from both its consanguinity with its depiction (and the Necker Cube) and the effect of lighting, whilst reversals of the cone derive from only the latter.…”