The Law of Combination in Recall
Unitary response to multiple stimuli is important in recall as well as in learning. The clearest case of this is afforded by "controlled association". [Footnote: [See p. 381.]]
In an opposites test, the response to the stimulus word "long" is aroused partly by this stimulus word, and partly by the "mental set" for opposites. There are two lines of influence, converging upon the response, "long--short" (of which only the word "short" may be spoken): one line from the stimulus word "long", and the other from the mental set for pairs of opposite words. The mental set for opposites tends to arouse any pair of opposites; the word "long" tends to arouse any previously observed group of words of which "long" is a part. The mental set, an internal stimulus, and the stimulus word coming from outside, converge or combine to arouse one particular response.
The mental set for adding has previously exercised [{414}] linkages with the responses composing the addition table, while the mental set for multiplication has linkages with the responses composing the multiplication table. When the set for adding is active, a pair of numbers, seen or heard, together with this internal stimulus of the mental set, arouses the response that gives the sum; but when the multiplying set is active, the same pair of numbers gives the product as the response. All thinking towards any goal is a similar instance of the law of combination.