One hundred years of an ambiguous figure: happy birthday, duck/rabbit.

In the present study, Jastrow's famous ambiguous drawing of a duck/rabbit was presented to 100 students along with 11 published variants from later research. The beak/ears of the animal pointed to the right for half of the subjects and to the left for the other half. For each figure subjects were required to rate the ease of bird and of rabbit identification on a 9-point scale. Raw data of subjects' ratings are presented for the convenience of experimenters planning research with a specific bird/rabbit figure. Of the 12 figures, 6 were significantly bird-dominant, 2 were rabbit-dominant, and only 4 figures were truly ambiguous, i.e., a bird was as easily identified as was a rabbit. With the exception of one figure (the whole-body representation of a duck/rabbit), bird and rabbit ratings were not affected by the orientation of the beak/ears. Jastrow's original drawing was the seventh out of the 12 figures in rated ambiguity, suggesting a secure place for it in research on visual ambiguity.