Trial and error and the law of effect

     During the time when classical conditioning was being developed in Russia by I .Pavlov the same interest for learning and its experimental study started in the United States. Edward Thorndike (1874-1949) who was a student of William James at Harvard University decided to study animal intelligence and more specifically animal learning (his first publication in 1911 will be entitled “Animal intelligence: experimental studies”).

     According to Thorndike,  learning  is the result of an association between the stimulus and the response which is governed by the Law of effect: when a situation triggers several responses, the one that are followed by a satisfactory state will have more chances to reproduce.


   E. Thorndike built cages that can only be opened with a special mechanism, which the cat (or the dog) must learn to open in order to get the food placed outside of the cage. The cage is called “puzzle box”.

   Once placed in the cage, the animal presents all kinds of varied and wrong behaviors to open the door of the cage. Then accidently by rubbing against the walls, or pawing, the opening mechanism engages. Thus the cat gets out of the cage and eats the food.


 After repeating this procedure many time and after the animal learns how to get out from the cage through trial and error and since this behavior had favorable consequence "food". the time needed to open the door will decrease, and the wrong responses will be reduced, to keep only the right response.


  • Thorndike, E. L. (1898). Animal intelligence: An experimental study of the associative processes in animals.

  • Thorndike, E.L. (1905) Elements of psychology. A. G. Seiler, New York.

  • SCIENCE HUMAINE N°3- SEPTEMBER 2000 – 48 F. P(26-27)

See Also:

Classical Conditioning

Behavior therapies

Conditioning Watson and little Albert


Operant Conditioning