Bias in the priming of object decisions.

Seven experiments examined priming effects for 3-dimensional line drawings in the object decision task. One of the most important previous findings about object decisions has been that the decision about a possible object is primed by previous presentation of the object, but the decision about an impossible object is not. Through the use of manipulations that can eliminate processes that retrieve episodic information (response time deadlines, memory load, forced choice, and similarity), equal size effects on impossible and possible objects were obtained. This is interpreted to mean that priming effects reflect a bias to respond "possible," which can be opposed for impossible objects by episodic information so as to yield the approximately null priming effect for impossible objects found in past experiments.