Joachim
Hoffmann &
.When an observer
looks at the inside of a mask or mould of a face from a certain
distance, the mask often appears as a normal convex hemispherical face
(the hollow face illusion, Gregory, 1973). A hollow mask provides
ambiguous depth information: Whereas the pictorial cues reactivate
face-representations which offer the knowledge about their typical
convex shape, stereoscopic cues indicate the concave shape of the mask.
The contradiction is resolved in dependence on which information
currently dominates perception: The illusion of a convex face emerges
if
the reactivated knowledge prevails and a hollow mask is correctly
perceived if the stereoscopic information prevails.
The present research project
explores, for our knowledge for the first time, where the eyes gaze if
observers look at an illusionary face. More precisely, we ask at which
distance the eyes converge if observers are asked to fixate the tip of
the nose of a hollow mask: Do the eyes diverge to the far location of
the tip of the real nose or do they converge to the near location of
the
illusionary nose?
Vergence movements of the
eyes for fixation are goal oriented actions like any other voluntary
action. Accordingly, the issue whether the hollow face illusion affects
vergence movements is related to the question to what degree visual
illusions deceives not only perception but also actions. Furthermore,
the research may contribute to the current controversy whether or not
perception and action rely on different visual pathways (dorsal and
ventral).
Updated: 30.01.2008