Our constant consideration should be for the fact, emphasized by William James, that there is "no recall without a cue."[29] Here we have a scratching sensation provoked by a mouse as the immediate and demonstrated cue. The images that followed in serial response, proved upon investigation to have been wholly derived from a certain conversation with Dr. X., the night before. The subject had been reflex-action and especially the scratch-reflex of the guinea-pig[30] as investigated by Sherrington; we had discussed also the attempts of other authors to explain the higher mental functions in terms of reflex-action.([31]) My own preference for such studies as applied to the explanation of dreams had been touched upon. This preference had in turn been contrasted with the fact that I was at the time of the dream called upon to spend much time studying histological specimens through the microscope. Incidentally, I told him that this was bad for my eyes, and likewise, I had complained that his dreams were not written out clearly enough to suit my purpose to study them carefully. Such interest had been aroused in the subject of reflexology, that Dr. X. and I had stayed up late that night discussing it.
A study of the dream in the light of these facts will show how perfectly the dreaming mind appears to have "taken advantage of" them—in reality following cues along the lines of least resistance.
THE DREAM AS A RESPONSE TO A CUE
The Scratch-Reflex dream is then to be reconstituted first of all as a memory-reaction determined by factors of recency, frequency and intensity in the dreamer's experience. The operation of these factors determines the evocation of a specific context or apperception-mass, namely the conversation in question, whose affinity with the external stimulus (scratching) is now made evident. The course of events can be followed so concretely as to permit the logical exclusion of other supposed determinants; confining the explanation as stated. The principle of the parsimony of causes is here applied. I contend that the dream is neither an infantile nor a sexual wish-fulfilment, all plausible analogies to the contrary notwithstanding. Should anyone wish to urge the more remote interpretations which I first manufactured, then the burden of proof rests with him. And no proof is conclusive that rests on mere precedent or on mere reasoning by analogy. The only psychological proof of an interpretation is fundamentally the ability of the interpreter to reconstitute the dream beyond peradventure. This I propose to accomplish more in detail, showing the dream to be a reaction to specific cues, through a process of trial-and-error, and to a limited degree, of trial and success.
TRIAL PERCEPTS
Consider the sequence of events: the dream pictures are all related, at least individually, to the conversation in question: microscope, slide, reflex and "scratchiness" are all so many pictures jig-sawed out from this very context or apperception-mass. The scratching sensation, we must suppose, evoked these pictures serially, in the order stated. If these images were what the psychologist calls "trial percepts," we would expect from them just what we do find, namely, an increasing degree of correspondence (relevancy) between the stimulus-idea and the images, as they appear.[33] Precisely so, the images of microscope, slide, reflex and scratchy handwriting, as they successively come into focus, conform more and more to the nature of the stimulus, until the approximation ends in the idea of an all-absorbing interest in "scratchy" marks. This visual image hardly reaches precision before it becomes translated and transposed to the tactile field of my ear; smoothly, as if it were one magic lantern view dissolving into another. In fine, the presentation of each image in the dream amounts to a groping effort of the dreamer's nervous system to find a proper experiential EQUIVALENT for the arriving stimulus. It is a trial-and-error method of perceiving or apperceiving a stimulus by marshelling associated ideas; in this case they are serially evoked; (what might be called "oniric echelon"); in other cases the trial apperceptions are blended smoothly (oniric fusion) or heaped together in rough-and-tumble fashion, a kind of confusion (conveniently called "oniric entassement") which testifies sufficiently to the failures of the Unconscious t o dispose smoothly of arriving excitations, and so emphasizes; the theory of trial-and-error, as applied to dreams.
APPERCEPTIVE DELAY IN TRIAL-AND-ERROR PROCESS
The delay in arriving at the correct apperception of the stimulus may be referred to as "finding-time" or simply as apperceptive delay. It represents time occupied with the reproduction of erroneous apperceptive images—apperceptive errors. Meanwhile the stimulus-idea, that mental element most closely connected with the original stimulus, is operating somewhere in the brain, determining the evocation of the secondary images that appear in the dream.[33] This wire-pulling is done in the dark; the primary stimulus-idea is not itself imaged, at first; neither is the context or apperception-mass which meets it half-way, that is, becomes conjoined with the stimulus-idea. Indeed, the images that come into the dream are only emerging peaks of a submerged island of memory. What shall emerge is determined by the interplay of stimulus-idea and apperception-mass, below the level of consciousness. (A and Z are working together.)
The particular "island of memory" in this case, was an impression of the talk with Dr. X., about histology, reflexology and dream interpretation; it remained subliminal, evidently, except so far as portions of it were raised above the threshold by the reproductive energy of the stimulus of scratching. Necessarily, a process of imageless thought had taken place, whereby the conversation was brought into play as a sub-excited apperception-mass or setting-of-ideas for the stimulus-idea. Furthermore, another process of imageless thought must have taken place whereby the secondary images being raised into consciousness attained to their arrangement as a wish-phantasy, without that preliminary tuning-up which the principal cue (scratching) called forth, on its own account. This remains to be explained.