A set of experiments were carried out in the 1940s by Fritz Heider and Marianne Simmel, in which they investigated attributional processes in perception. Participants were shown a short animation, in which three geometrical figures (a large triangle, a small triangle and a disc) were shown moving in various directions and at various speeds. The only other figure in the field was a rectangle, a section of which could be opened and closed as a door is. When asked to interpret the moving objects, subjects were found to interpret the animation in terms of animated beings, attributing motives and personality.
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