Also known as Lincoln's top hat illusion and Wundt-Fick illusion. All three terms refer to a size optical illusion or a "geometric-optical illusion involving the top hat or stove pipe hat worn on certain photographs by US President Abraham Lincoln (1809-1865). While the hat appears to be tall, it is in fact just as wide as it is tall. The eponym Wundt-Fick illusion refers to the German father of psychology Wilhelm Wundt (18321920), and the German physiologist Adolph Fick (1829-1901), although it was Fick alone who described the concomitant illusion in his dissertation of 1851. The top hat illusion should not be confused with the "hat illusion, which refers to a " tactile hallucination or " illusion reported in the context of sleep deprivation experiments.
References
Fick, A. (1851). Da errone quodam optic asymme-tria bulbi efecto.Marburg:Koch.
Ninio, J. (2001). The science ofillusions.Trans-lated by Philip, F. Ithaca, NY: Cornell University Press.
Dictionary of Hallucinations. J.D. Blom. 2010.