respo~ses of female mice to male urine odors. Physiology and BehaVIor, 1970, 5, 407- Two experiments are reported in which subjects viewed a film of an automobile accident and then answered questions about events occurring in the film. Relative to questions containing an indefinite article (e.g., Did you see a broken headlight?), questions which contained a definite article (e.g., Did you see the broken headlight?) produced (1) fewer uncertain or "I don't know" responses, and (2) more "recognition" of events that never, in fact, occurred. The results, which are consistent with the view that questions asked subsequent to an event can cause a reconstruction in one's memory of that event, have important implications for courtroom practices and eyewitness investigations.