The problem to be taken up and the point at which the search for a solution will begin are

customarily prescribed by the investigator (1)_____ a subject participating in an (2)_____ on thinking (or by the programmer for a computer). (3)_____, prevailing techniques of (4)_____ in the psychology of thinking have invited (5)_____ of the motivational aspects of thinking. The conditions that determine when the person will begin to think in (6)_____ to some other activity, what he will think about, what direction his thinking will take, and when he will regard his search for a solution as successfully terminated (or abandon it as not worth pursuing further) (7)_____ are beginning to attract investigation. (8)_____ much thinking is aimed at (9)_____ ends, special motivational problems are raised by "disinterested" thinking, in which the (10)_____ of an answer to a question is a source of satisfaction in itself.

For computer specialists, the detection of a mismatch between the formula that the program so far has (11)_____ and some formula or set of requirements that (12)_____ a solution is what impels continuation of the search and determines the direction it will (13)_____.

Neo-behaviorists (like psychoanalysts) have made much of secondary (14)_____ value and stimulus generalization; i.e., the tendency of a stimulus pattern to become a source of satisfaction if it resembles or has (15)_____ accompanied some form. of biological gratification. The insufficiency of this kind of explanation becomes apparent, (16)_____, when the importance of novelty, surprise, complexity, incongruity, ambiguity, and (17)_____ is considered. Inconsistency between beliefs, between items of incoming sensory information, or between one's belief and an item of sensory information (18)_____ can be a source of discomfort impelling a (19)_____ for resolution through reorganization of belief (20)_____ or through selective acquisition of new information.

A．for

B．into

C．with

D．by