The kerplunk experiment was a famous stimulus and response experiment conducted on rats and demonstrates the ability to turn voluntary motor responses into a conditioned response. The purpose of the experiment was to get kinaesthetic

Kinesthetic learning

Kinesthetic learning is a learning style in which learning takes place by the student actually carrying out a physical activity, rather than listening to a lecture or merely watching a demonstration. It is also referred to as tactile learning...

 feedback rather than guidance through external stimuli through maze learning. It was conducted in 1907 by John B. Watson

John B. Watson

John Broadus Watson was an American psychologist who established the psychological school of behaviorism. Watson promoted a change in psychology through his address Psychology as the Behaviorist Views it which was given at Columbia University in 1913...

 and Harvey A. Carr

Harvey A. Carr

Harvey A. Carr was an American Psychologist and developer of functionalism. Along with John Dewey and James Rowland Angell, he is credited with the development of functionalism as a school of thought, leading American psychology toward a functionalist approach...

 and was named after the sound the rat made after running into the end of the maze. The study would help form a chain of responses hypothesis proposed by Watson.

The studies findings would later give credibility to stimulus and response interpretations that rewards work by strengthening the learned ability to show a habitual motor action

Motor skill

A motor skill is a learned sequence of movements that combine to produce a smooth, efficient action in order to master a particular task. The development of motor skill occurs in the motor cortex, the region of the cerebral cortex that controls voluntary muscle groups.- Development of motor skills...

in the presence of a particular stimulus.

The experiment

Rats were trained to run in a straight, alley like maze for a food reward which was located at the end of the alley. Watson found that once the rat was well trained, it performed almost automatically on reflex. Upon learning the maze over time, they started to run faster through each length and turn. By the stimulus of the maze, their behavior became a series of associated movements, or kinaesthetic consequences instead of stimulus from the outside world. This routine continued until the length of the path changed, either farther or shorter.

If the conditioned rats were released into an alleyway or path that was shortened, they would run straight into the end of the wall making a "kerplunk" sound. The first trial found that they would run full speed, passing up the food that had been moved closer. Shortening the alleyway, and moving the food closer was an early signal that was ignored by the rats.

If the path was longer, the rats would run as usual until it reached their customary distance, the distance at which the food would normally be. They would then pause to sniff the area even though they had not reached the end of the alley, often ignoring food that was farther away.