One of the findings from research with patients who had the upper parts of their cerebral hemispheres split was the discovery of a brain function called the "interpreter." When a subject performed or said something they couldn’t understand themselves (because it was a response from their isolated hemisphere), the "interpreter" would immediately and swiftly create a rational explanation—even if it had no basis in fact. For example, if the experimenter instructed the subject in one ear to stand up, and then asked in the other ear why they had done so, the subject would respond with something like, “Oh, I just wanted to get a Coke.” Countless variations on this test yielded the same result, though the rationalizations were sometimes quite unexpected. This may explain why people who choose an action or a stance for emotional or unconscious reasons never seem to struggle to rationalize it afterward.
Traufetter shares an anecdote from neuroscientist Wolf Singer, who, as a student, hypnotized subjects to perform a certain action upon hearing a neutral word. When later asked why they carried out these actions, they responded readily—not only for simple tasks, like closing a window, but even for unusual commands, such as “unscrewing the bulb from a lamp and placing it in a flowerpot.” The subjects always had complete rationalizations ready; Singer, for example, was told, “I’ve always wondered what would happen if you put a light bulb in a flowerpot.”