What is the conditioned reflex?

John B. Watson, answered from the texts and cited to the page.

John B. Watson answers

The conditioned reflex is the mechanism by which any stimulus that does not ordinarily call out a fundamental or native reflex can be made to call it out, provided the proper conditions are observed.¹ Every fundamental reflex in the body has its appropriate stimulus — touch the patellar tendon and the leg kicks; prick the finger and it draws back; put acid in the mouth and the salivary glands pour out their secretions.¹

The question is whether we can get a transfer or substitution of stimulus, whether some other signal, paired correctly with the adequate stimulus, can be made to trigger the same response. The answer is that we can.¹ Pavlov and his students showed this most clearly with the dog and the salivary reflex, and Lashley's sialometer — a small silver disc fitted to the inner surface of the cheek — made the same measurement possible in man.²

Once you have the conditioned reflex established, its properties are lawful and precise: it weakens without practice and can break down, but can be quickly reestablished; the substituted stimulus can be made specific, so that no other stimulus of its class will serve; the magnitude of the response varies with the strength of the stimulus; and the reflex can be extinguished by rapid repetition without reinforcement.³

What makes this more than a laboratory curiosity is what it builds. Every complicated habit, when fully analyzed, resolves into a chain of just such units.⁴ The conditioned reflex is the unit out of which the whole habit is formed — typewriting, piano playing, the navigation of a maze, the emotional life of the adult. Show a man a visual stimulus, condition him to turn right; he faces a second stimulus, condition him to walk forward; and so on through the whole series until he has traversed the room and returned to the starting point.⁴

That is not a metaphor for how habits work; it is a description of the actual mechanism. Strip any complex skill down to its elements and what you find, at each node, is a conditioned reflex — a stimulus, a response, and a history of pairings that locked them together.

Sources

1. The question before us is whether we can get any other stimulus to touch off such a fundamental or native reflex — whether we can get a transfer or substitution of stimulus. Without entering too much into the details of the method, we find that it is possible to get a stimulus which does not ordinarily call out one of the fundamental reflexes to call it out, provided the proper conditions are observed.

   Psychology from the Standpoint of a Behaviorist

2. Dr. K. S. Lashley, however, has perfected a small instrument which serves the same purpose. It consists of a small silver disc about the diameter of a 5-cent piece and about 1½" thick, grooved on one surface so as to form two non-communicating chambers.

   The Ways of Behaviorism

3. The conditioned responses, like all other habits, are more or less temporary and unstable. After periods of no practice they cease to work; they break down. They can, however, be quickly reestablished.

   Behaviorism

4. It is the relationship apparently of part to whole — that is, the conditioned reflex is the unit out of which the whole habit is formed. In other words, when a complicated habit is completely analyzed, each unit of the habit is a conditioned reflex.

   Behaviorism