Effect of Methylphenidate Hydrochloride (Ritalin) on Psychophysical Judgments by Chimpanzees

Abstract

To 1 chimpanzee dosages of 0.11, 0.22, and 0.44 mg./kg. Ritalin were administered twice in tablet form and psychophysical measurements made over the following 3½ hr. The 0.22 mg./kg. dosage improved psychophysical judgments and did not alter response latency. The 0.11 mg./kg. dosage altered neither. The 0.44 mg./kg. dosage decreased latency and produced a decrement in judgment. The psychophysical methodology may offer a more sensitive technique in arriving at optimal and lower dosages of various drugs than the frequently used response to presence or absence of a stimulus or locomotor activity.