1 Simple Experiments on the Physics of Vision

The experiments related to the physics of perception, particularly those concerning the visual system, are particularly attractive: by using only extremely simple materials it is possible to get amazing results. The experiments based on the working of the eyes can be easily understood from the basic principles of geometrical optics. The analysis of what happens in the retina after the light has activated the sensors is a much more complex subject and this complexity increases as the impulses transmitted by the optic nerve propagates in the brain through the successive stages where their analysis is performed1. Many experiments based on visual illusions are difficult to analyze since, often, these illusions arise from the treatment of the signals in the nervous cells of the retina and in the brain2. Thus, only the experiments based on the "optical components " of the eye will be discussed here. Even so, the range is quite broad and only the most relevant ones have been quoted