A size illusion of the letter 'P'.
The perceived size of 'P' and 'p' is influenced by their vertical position relative to nearby letters. In the experiments reported here, we show that uppercase 'P' appears smallest when it is displaced downward toward the letter's lowercase position, whereas lowercase 'p' appears largest when it is near the uppercase position. Our results show that this P-illusion not only occurs in the presence of nearby letters, but is also found when 'P' is displaced relative to a nearby horizontal line. This type of size illusion seems to clearly occur only with 'P' and 'p', and we suggest that it is a result of learning to read and recognize letters in the English alphabet.
Katz
M
M
Department of Vision Sciences, State University of New York, State College of Optometry, NY 10010, USA.
Pola
J
J
D006801:Humans; D009903:Optical Illusions; D011594:Psychometrics; D012858:Size Perception