In treating the facts recorded in the accompanying tables as phenomena of inhibition no assumption is implied, it may be well to repeat, that the ideational images are forces struggling with each other for mastery.  Nor is it implied, on the other hand, that they are wholly unconditioned facts, unrelated to any phenomena in which we are accustomed to see the expression of energy.  Inhibition is meaningless save as an implication of power lodged somewhere.  The implication is that these changes are conditioned and systematic, and that among the conditions of our ideas, if not among the ideas themselves, power is exerted and an inferior yields to a superior force.  Such force, in accordance with our general presupposition, must be neural or cerebral.  Even mental inhibition, therefore, must ultimately refer to the physical conditions of the psychical fact.  But the reference, to have any scientific value, must be made as definite as the case will allow.  We must at least show what are the conditions under which a state of consciousness which might otherwise occur does not occur.  When such conditions are pointed out, and then only, we have a case of what has been called psychical inhibition; and we are justified in calling it inhibition because these are precisely the conditions under which physiological inhibition may properly be inferred.  And, we may add, in order that the conditions may be intelligibly stated and compared they must be referable to some objective, cognizable fact.  Here the accessible facts, the experiential data, to which the psychical changes observed and the cerebral changes assumed may both be referred, are visual objects, namely, the figures already described.

What may occur when these objects are precisely alike, and are seen under conditions in all respects alike except as to spatial position, is indicated in Table I. The general average shows that the image referred to the left-hand object was seen some 30 seconds per minute; that referred to the right-hand image, some 31 seconds.  Sometimes neither image was present, sometimes both were reported present together, and the time when both were reported present is included in the account.  In this series it appears, on the whole, that each image has about the same chance in the ideational rivalry, with a slight preponderance in favor of the right.  Individual variations, which may be seen at a glance by inspection of the averages, show an occasional preponderance in favor of the left.  But the tendency is, in most cases, towards what we may call right-handed ideation.

Series No.  II.—­In the second series (Table II.) we find that, other things being equal, an increase in the relative complexity of the outline favors the return of the image to consciousness.  Including the time when both images were reported present at once, the simpler appears but 27 seconds per minute as against 34 seconds for the more complex.  No attempt was made to arrange the figures on any regularly increasing scale of complexity so as to reach quantitative results.  The experiment was tentative merely.