© C.O. Evans
 Interrogative attention is typically the attention manifested in problem-solving. In a problem-solving context there may be a number of factors that are thought to be relevant to the solution of the problem. When these simultaneously occupy attention there is no question of the investigator being distracted by them. He will only feel distracted by things that have no relation to the object of enquiry. Let us define as a 'relevancy system' the sum of those considerations that are taken by the attender to have a bearing on
his investigative task. A 'divided attention' can then be said to be one in which the objects of attention do not both belong to a reigning relevancy system. When that happens we have a conflict between objects of attention. It should not be overlooked that there is an upper limit to attention which is reached even when one's mind is wholly occupied with a single relevancy system. This occurs when the relevancy system is too complex for all the considerations to be kept before the mind at once. Naturally the limit of attentive tolerance beyond which there is a breakdown of attention will vary from person to person.
The notion of a relevancy system enables us to solve the problem of whether or not it is possible to pay attention to two or more objects of attention simultaneously. When two objects of attention compete for the subject's attention they cannot belong to the same relevancy system. In that case we can only attend to the one at the expense of the other.
To put it differently let us suppose that x is the object of attention of relevancy system S and y that of S'. Now if by paying attention to xconsciousness of necessity 'organizes around' x, then y can only become the object of attention by consciousness 'organizing around' y. But it can only do that by destroying its organization around x; i.e. by altering the reigning relevancy system from S to S'. If we find a further object of attention z to which attention may be paid without altering the relevancy system reigning at the time, then z is in no sense a rival object of attention. Whether we would wish to say that in those circumstances attention was being paid to two objects at once, say x and z, or whether we would wish to say that x and z are elements of a compound object of attention seems to me to be a purely terminological question. If a relevancy system were defined as having a single object of attention, we would have opted for the 'compound object' description. However, I see no advantage in that, and to suit myself I shall take the position that we may have more than one object of attention at a time provided they belong to a single relevancy system.
In view of the complexity of the relationship between unprojected consciousness and object of attention in interrogative attention, it is possible to give a more satisfactory interpretation of Hamilton's law of limitation than the one he gives. The degree of intensity of attention must no longer be correlated in simple inverse proportion to the number of objects receiving attention. We must not take it that attention to one object will be ntimes
greater than attention to n objects. The argument of this chapter points to the conclusion that the greater the connectedness between unprojected consciousness and attention, the greater the degree of attention. Interrogative attention is at its maximum when unprojected consciousness and object of attention form a single relevancy system. From this point of view, the complexity of the relevancy system - provided it is not over-complex -is no distraction to attention. On the contrary, the greater the extent to which unprojected consciousness is drawn into the relevancy system the greater will be the concentration of attention. The threat to attention from extraneous elements of unprojected consciousness detaching themselves from unprojected consciousness and obtruding on attention will then be all but nonexistent.