Through the inverting glass: first-person observations on spatial vision and imagery

Experience with inverting glasses reveals key factors of spatial vision. Interpretations of the literature based on the metaphor of a visual image have raised the question whether visual experience with inverting glasses remains inverted or whether it may turn back to normal after adaptation to the glasses. Here, I report on my experience with left/right inverting glasses and argue that a more fine-grained sensorimotor analysis can resolve the issue. Crucially, inverting glasses introduce a conflict at the very heart of spatial vision. At first, the experience of visual direction grounded in head movements differs from visual experience grounded in eye movements. During adaptation, this difference disappears, and one may learn to see without conflict where objects are located (this took me 123 h of practice). The momentary experience became once again integrated within the larger flow of visual exploration involving head movements, a change of experience that was abrupt and comparable to a Gestalt switch. The resulting experience remains different from normal vision, and I argue that this difference can be understood in sensorimotor terms. I describe how adaptation to inverting glasses is further reflected in mental imagery, supporting the idea that imagery is grounded in sensorimotor engagement with the environment as well.