The discussion concerning the possibility of “imageless” thought, while an interesting one, cannot be entered into here.  Whether “meanings” can exist in the human mind apart from any carrier in the form of some sensory or imaginal state is unsettled, but the discussion has drawn attention to at least the very fragmentary nature of those carriers.  A few fragments of words, a mental shrug of the shoulder, a feeling of the direction in which a certain course is leading, a consciousness of one’s attitude towards a plan or person—­and the conclusion is reached.  The thinking, or it may even have been reasoning, involved few clear-cut images of any kind.  The fragmentary, schematic nature of the carriers and the large part played by feelings of direction and attitude are the rather astonishing results of the introspective analysis resulting from this discussion.  This sort of thinking is valuable for the same reasons that thinking in terms of words is valuable—­it only goes a step further, but it needs direction and training.

Images of all kinds have been discussed as if they stood out clearly differentiated from all other types of mental states.  This is necessary in order that their peculiar characteristics and functions may be clear.  However, they are not so clearly defined in actual mental life, but shade into each other and into other mental states, giving rise to confusion and error.  The two greatest sources of error are:  first, the confusion of image with percept, and second, the confusion of memory image with image of the imagination.  The chief difference between these mental states as they exist is a difference in kind and amount of associations.  These different associates usually give to the percept a vividness and material reality which the other two lack.  They give to the memory image a feeling of pastness and trueness which the image of imagination lacks.  Therefore lack of certain associations, due to lack of experience or knowledge, or presence of associations due to these same causes and to the undue vividness of other connections, could easily result in one of these states being mistaken for another.  There is no inherent difference between them.  The first type of confusion, between percept and image, has been recently made the subject of investigation.  Perky found that even with trained adults, if the perceptual stimulus was slight, it was mistaken for an image.  All illusions would come under this head.  Children’s imaginary companions, when really believed in, are explained by this confusion.  However, the confusion is much more general than these illustrations would seem to imply.  The fact that “Love is blind,” that “We see what we look for” are but statements of this same confusion, and these two facts enter into multitudes of situations all through life.  The need to “see life clearly and see it whole” is an imperative one.

The second type of confusion, between reproductive and productive memory, is even more common.  The “white lies” of children, the embroidering of a story by the adult, the adding to and adding to the original experience until all sense of what really happened is lost, are but ordinary facts of everyday experiences.  The unreliability of witness and testimony is due, in part, to this confusion.