Unusual visual phenomena are used to study perception and the following stages, characterized by: aesthetic appreciation and judgment; contributions from cognitive and emotional factors - and a combined cognitive judgment, wonder and a strong positive emotion, colloquially known as 'the wow factor'. Examples of the latter are impressions of 'super depth' and 'super sharpness'; they may occur after cataract operations but also may follow less dramatic visual events. The research methods used are personal observation with introspection, and interviews. An important feature of many unusual visual phenomena is their temporariness, with, however, often the possibility to re-evoke them. Explanations to a certain extent may be found in Bayesian reweighting of perceptual criteria and also in neuroscience, in particular neuroaesthetics.