Some theorists hold that personal-level, conscious visual representations are for object recognition whereas unconscious visual information is employed for the control of movements. A study by Króliczak, Heard, Goodale, and Gregory (2006) lends support to this view. They used the hollow-face illusion, in which one looks at a hollow mask but consciously perceives it as a normal convex face. Subjects were asked to estimate the positions of small magnets that were stuck to an actually hollow but seemingly normal face and then to use their fingers to ‘flick’ the magnets off. It turned out that even though they reported a strong illusion of a normal face, their flicking movements were aimed at the actual and not the illusory positions of the target.
On the basis of their findings, Króliczak et al. write that an identical visual stimulus can have entirely opposite effects on conscious perception and visual control of fast action. Interestingly though, when subjects were asked to slow down their movements, Króliczak et al. didn’t obtain visuomotor immunity to the illusion. Other studies too found that illusions and perceived size can have a significant effect on action especially when movements are performed more slowly (Goodale 2008; Bruno and Franz 2009).
This suggests that, while unconscious visual representations support immediate rapid action, conscious visual representations have the feature of being integrated with knowledge from the past and the context to plan future action. For the hollow face illusion is typically taken to be the result of knowledge-driven influences on perception: our everyday experience with numerous convex faces leads us to expect convexness and to overlook other cues indicating that what we are in fact looking at is a concave mask. Perhaps, then, unconscious visual representations are for fast/automatic movements whereas personal-level, conscious visual representations have the feature of serving object recognition and slower/more reflective movements.