David Premack American animal psychologist Country: USA

Biography of David Premack

David Premack (born 1925) is an American zoopsychologist who worked at the University of Pennsylvania on issues of conditioning and reinforcement. He is best known for his theory of the "premack principle," which states that any dominant response can serve as a reinforcer for a preceding weaker response. This means that behavioral acts do not necessarily have to be at the end of a behavioral chain in order to function as reinforcement. Premack published this theory in his paper "Toward empirical behavior laws: Positive reinforcement" in the journal "Psychological Review" in 1959.

One of Premack's most famous experiments involved teaching a chimpanzee named Sarah to use signs. Prior to Premack's work, R. and B. Gardner had successfully taught a chimpanzee to use a complex system of signs, similar to those used by deaf individuals in America. Premack, however, used plastic symbols as "words" that the chimpanzee had to place on a magnetic board. Through this method, Sarah learned around 130 signs and was able to form relatively complex sequences or "phrases." This research was published in the journal "Science" in 1971.

The elements of this methodology were originally developed in the 1930s by N.N. Ladygin-Kotz.