In 1964, at the Langley Porter Psychiatric Institute of the University of California at San Francisco, Dr. Joe Kamiya was able to train sleeping subjects to recognize they were in REM dreaming and indicate this by pressing micro switches on their thumbs (other research has shown that dreamed movements of the fingers can manifest as small physical movements).

Using tones and mild shocks as cues, the experiments showed that the subjects were able to signal knowledge of their various sleep stages, including dreaming.

By bribing the subjects with monetary rewards, the dreamers could further learn to recognize dreaming and signal REM-knowledge without the cues, proving once again that, although money cannot buy love, perhaps it can buy lucidity.