Joseph Jastrow

Joseph Jastrow (1863–1944) was an American psychologist whose experiments examined perception, optical illusions, and judgment. He helped establish experimental psychology in the United States.

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G. Stanley Hall: An American psychologist who founded the first U.S. psychology laboratory and the American Psychological Association. Hall supervised Jastrow’s doctoral work and helped establish the institutional setting for his career.
Duck–rabbit illusion: An ambiguous drawing that can be seen as either a duck or a rabbit. Jastrow used this reversible figure to illustrate how perception depends on interpretation.
Ambiguous image: An image that supports more than one plausible interpretation. Jastrow’s reversible figures reveal how perception can shift while the stimulus remains unchanged.
University of Wisconsin–Madison: A public research university in Madison, Wisconsin, founded in 1848. Jastrow founded its psychological laboratory and built a center for experimental research.
William James: An American philosopher and psychologist known for shaping functionalist psychology and writing The Principles of Psychology. James and Jastrow were prominent figures in the early professional community of American psychology.
Jastrow illusion: An optical illusion in which two equal curved shapes appear unequal when placed side by side. This illusion is named for Jastrow and exemplifies his interest in misleading visual comparisons.
Perceptual set: A readiness to perceive or interpret stimuli in a particular way, shaped by expectation and experience. A prepared interpretation can determine which meaning of an ambiguous figure becomes visible.
American Psychological Association: A professional organization for psychologists in the United States, founded in 1892. Jastrow was among the early leaders who helped organize psychology as a profession.
Hugo Münsterberg: A German-American psychologist who applied psychological research to law, industry, and everyday life. Münsterberg shared Jastrow’s interest in applying experimental psychology beyond the laboratory.
Rabbits in a burrow: A reversible figure in which the same lines can be perceived as rabbits or as a burrow. Jastrow used the figure to demonstrate how expectations guide the organization of visual forms.