|Retinal C20H280 in the normal (top) and activated (bottom) configurations.|
The bending of retinal results in the triggering of a nerve impulse in the optic nerve and thus to mental processing and reaction to visual information.
The movement of the retinal to external force is a type of induced movement.
The retinal molecule light reactivity behavior makes it an ideal model to the understanding of the mind body problem; it is, so to say, a modern upgrade to the older Cartesian automaton problem, to which Rene Descartes mused "I think, therefore I am".
The molecular formula of the human, a twenty-six element molecule, is simply an expanded version of the retinal molecule. In the retinal molecule, the hydrocarbon structure at the location of the eleventh and twelfth carbon atoms acts as the 'mind' of the retinal, just has the hydrocarbon structure of the brain, comprised mostly of docosahexaenoic acid (gray matter) and eicosapentaenoic acid (white matter), is the 'mind' of the human molecule. 
The person new to this subject will quickly object on the grounds that the human has consciousness, free will, choice, is alive, has a soul, among other olden days descriptors, etc., and that the retinal model does not apply. These objections, however, are not in accordance with modern chemistry.
1. Casiday, Rachel and Frey, Regina. (date). “Vision and Light-Induced Molecular Changes.” Department of Chemistry, Washington University in St Louis.
2. Thims, Libb. (2008). The Human Molecule (pg. 61). LuLu.
● Retinal – Wikipedia.