To speak of a law of Interest has the required impartiality of emphasis as between conation and feeling, though if the hypoth esis defended in another section turns out to be justified, the emphasis should ultimately be placed upon conation. So inter preted the three sub-laws would fall into line in a general formu lation : that the strength (or revivability) of an association de pends upon the frequency, recency and intensity of conative ac tivity in a given direction.
These laws, however, are not independent. Strictly, we should say: the more frequently or recently a conative tendency of given intensity has been furthered by the passage of thought from A to B the greater ceteris paribus the tendency for B to be revived by A. There is the possibility of interference or compensation between the effects of recency and frequency and greater fre quency or recency may balance a weakness in intensity, but no amount of frequency will increase the tendency for B to be revived, when its revival would be adverse to the general conative trend. This is most evident in the special case of motor associa tions. The more frequently or recently a certain end has been furthered by a given response, the greater the tendency for the response to be confirmed. But where the movement is adverse to the fulfilment of purpose neither frequency nor recency will serve in the least to confirm it.
The same principles are operative in the association of ideas. Ideas tend to be revived in accordance with the conative trends of thought. It is true that painful as well as pleasant ideas tend to be revived. But, painful ideas may be relevant to the trends of thought. Apart from such relevance they fail to be revived. Simi larly unpleasant actions tend to be repeated and painful habits formed in the pursuit of remoter ends, though not otherwise.
But this law, however much it may be amplified, refers only to the past, to the conditions of co-presentation and to prior cona tion. Explanations of mental process by reference to such condi tions alone fail to take account of the influences of the present, which determine the direction of associative revival. These are factors which are selective of what is relevant to and consonant with the present direction of endeavour. Hence, "necessity is the mother of invention." Associations relevant to the present ex igency are preferred.
Chief importance attaches in this connection to specific cona tive experiences, in particular to the awareness of the nature of the problem to be solved. The conceptual formulation of conation is what constitutes a "question," and the more clearly the ques tion is defined, the narrower is the range of associative relevance. Associative process is thus subject to multiple control. The train of ideas does not consist in a simple linear sequence, each item directly and independently leading to the next. Any particular sequence is under the general control of a governing idea—the idea of the end more or less clearly conceived. Such governance may depend upon a complex hierarchical organization of the con trolling ideas, with the most general logical notions standing at the head, and various kinds of "schemes" controlling the general lines along which the problem is treated. Where specific conation is absent we can still detect the influence of the vaguer emotive "moods." Depression favours unhappy memories, and gloomy prognostications. In joy, the train of ideas is similarly congruent with the mood. Such emotive states may be conatively defined.