University of Arkansas at Little Rock

John F. Kihlstrom
University of California, Berkeley

Technically, the duck-rabbit figure is an ambiguous (or reversible, or bistable) figure, not an illusion (Peterson, Kihlstrom, Rose, & Glisky, 1992). The two classes of perceptual phenomena have quite different theoretical implications. From a constructivist point of view, many illusions illustrate the role of unconscious inferences in perception, while the ambiguous figures illustrate the role of expectations, world-knowledge, and the direction of attention (Long & Toppino, 2004). For example, children tested on Easter Sunday are more likely to see the figure as a rabbit; if tested on a Sunday in October, they tend to see it as a duck or similar bird (Brugger & Brugger, 1993).

“When I’m looking at the photograph, I don’t tell myself ‘That could be seen as a human being’. Nor when looking at an F do I say: ‘That could be seen as an F’. If somebody showed me the figure and asked me ‘What is that?’, I could answer him only that way. –I couldn’t answer: ‘I take that to be a . . .’ or ‘Probably that is a . . .’ Any more than I take letters to be this or that when I’m reading a book.” Ludwig Wittgenstein