Educability.—"Education" may broadly be taken to cover every change in conduct resulting from prior stimulation and re sponse, excluding what is due to native constitution or natural un folding in accordance with immanent laws. The hard outlines of our original mechanical model, slightly tempered perhaps by the qualifications so far introduced, are further softened as we study the progressive modifications which our native constitution under goes. The problem of learning, relating as it does to changes in neural paths, inevitably suggests the very fundamental question how a reflex arc comes to exist at all ; for the factors responsible for their modification would seem, in large measure, to be re sponsible for their original formation. But to discuss this question would take us beyond the purview of the standpoint here adopted. For objective psychology the existence of the primary arcs is usually taken as a datum, and the questions to be raised are : how is a new response produced? and, how is an old response linked to a newer mode of stimulation? We may conveniently consider the latter, and simpler, question first.
A partial account is afforded by the principle of the condi tioned reflex. Given an original connection between a stimulus A and a response R, then any other stimulus, say B, which is ap plied concomitantly with A tends to acquire the capacity to evoke the response R independently of the presence of A. The case is well illustrated by the "salivary reflex." Certain kinds of sub stance being placed in a dog's mouth (stimulus A) directly pro voke a flow of saliva. If concomitantly with this a bell is rung (stimulus B),—the conjunction being repeated many times— the ringing of the bell will provoke the flow of saliva without the presence of the original stimulus. A response so acquired is said to be a conditioned reflex and the novel mode of stimulation a substitute stimulus. Much that is called education may be so explained.
Clearly, however, education covers a much wider range of modi fication. The principle, at best, would only account for a trans ference of established modes of behaviour to new situations. Our problem also relates to actual change in behaviour. Prima facie, four types of such modification call for explanation.
Firstly, we may note the atrophy or weakening of an old response ; secondly, facilitation or the strengthening of an exist ent response ; thirdly, the co-ordination of old responses into new and complex modes of behaviour ; and lastly, the intrusion of responses absolutely new.
It is one of the present limitations of the purely objective approach that no complete and satisfactory explanation of any of these forms of modification can be offered apart from teleo logical considerations or some reference to mind. The simplest ac count, as we shall later see, involves a reference to conation and to the satisfaction experienced in the course of such modification. Apart from this, all that we can do is to enumerate the quite specific conditions under which these modifications occur, and to attempt to describe the facts in purely bodily terms. The diffi culties are well illustrated in the more "original" forms of re sponse. Two cases call for consideration. First, any given re
sponse may admit of progressive modification until something quite different has emerged. This commonly occurs when partial facilitation is combined with partial atrophy. In learning a new and complex movement certain constituent acts come to be more pronounced whilst others undergo progressive elimination. We can describe the phases of the process quite objectively, but if we inquire why this particular movement becomes pronounced whilst that progressively disappears we are in general forced to refer to the utility of the change and more particularly to utility appreciated as such.
The second case is that in which there is a relatively abrupt intrusion of a novel mode of action, as when, for instance, we learn to manipulate a lock. But by this we are led to the question of practical intelligence.
Intelligence.—Intelligent action would seem the most diffi cult to reduce to a purely reflex scheme, since it essentially in volves a departure from routine. But to this problem, too, ob jective psychology can offer some relevant contributions. Struc tural organization in virtue of which the organism becomes in creasingly adaptable involves the integration of reflex arcs—and such adaptability is one factor in intelligence. A convenient start ing point for analysis is the complex behaviour cycles which are illustrated in instinctive action. But such a cycle differs in im portant ways from a mere chain reflex. In the latter the unit is the simple reflex and each response to stimulation constitutes at feast the principal factor provoking the subsequent act. Such systems are found in their greatest purity in purely immanent processes where the internal resources of the organism supply all that is necessary for the cycle to be performed. Where inter course with the external environment is involved, variability will arise, except where the needed cues are always ready to hand. In locomotion, for instance, there is the ground to walk upon or water in which to swim. It is series of acts such as these, not unitary reflex acts, which constitute the links of a behaviour cycle, but the latter does not merely consist in a longer chain. The sections, in the first place, are of variable dimensions, and transitions from phase to phase are conditioned by critical clues. The rhythm of locomotion continues until the prey is caught, mastication ensues until it is consumed, or appetite appeased. Even here the individual actions are adapted to the character of the ground and the nature of the food. There is in short a second characteristic of the behaviour cycle of paramount importance —the organization of alternatives. One must first catch one's hare, but when caught it can be cooked in various ways. The alternatives, of course, are not wholly arbitrary, and selection will be determined by a variety of subtle factors in the total situa tion, including the state of the body. The organization of alter natives may proceed until an almost inexhaustible repertoire of responses is available. Such is the endowment of the for tunate beings who are never at a loss in all the emergencies of life. The elaboration of such alternatives is the function of in telligence.