to repeat acts which have led to them; these are the situations which the animal is said to "desire" and in which it is said to "find satisfaction". This objection to Thorndike's first law is, therefore, not very serious, and need not further trouble us.
Dr. Watson considers one principle alone sufficient to account for all animal and human learning, namely, the principle of "learned reactions". This principle may be stated as follows:
When the body of an animal or human being has been exposed sufficiently often to two roughly simultaneous stimuli, the earlier of them alone tends to call out the response previously called out by the other.
Although I do not agree with Dr. Watson in thinking this principle alone sufficient, I do agree that it is a principle of very great importance. It is the modern form of the principle of "association". The "association of ideas" has played a great part in philosophy, particularly in British philosophy. But it now appears that this is a consequence of a wider and more primitive principle, namely, the associa tion of bodily processes. It is this wider principle that is asserted above. Let us see what is the nature of the evidence in its favour.
Our principle becomes verifiable over a much larger field than the older principle owing to the fact that it is movements, not "ideas", that are to be associated. Where animals are concerned, ideas are hypothetical, but movements can be observed; even with men, many movements are involuntary and unconscious. Yet animal movements and unconscious involuntary human movements are just as much subject to the law of association as the most conscious ideas. Take, e.g., the following example (Watson, p. 33). The pupil of the eye expands in darkness and contracts in bright light; this is an involuntary and unconscious action of which we only become aware by observing others. Now take some person and repeatedly expose him to bright light at the same moment that you ring an electric bell. After a time the electric bell alone will cause his pupils to contract.
