The Question of Non-Sensory Recall
Many observed facts are not strictly facts of sensation, though observed by means of the senses. Let us suppose, for an example, that your attention is caught by the bright green new leaves at the tips of the branches of an evergreen tree in summer, and that you notice also the darker green of the older leaves further back along the branches, and, exploring deeper, find leaves that are dead and brown, while still further in they have all fallen off, leaving bare branches reaching back to the trunk; so that you finally "see" how the tree is constructed, as a hollow cone of foliage supported by an interior framework of branches. All this has meant a lot of different reactions on your part, and the final "seeing" of how the tree is constructed would scarcely be called a sensation, since it has required mental work beyond that of simply seeing the tree. It is a response additional to the strictly sensory response of seeing the tree.
Now the question is whether this additional response can be recalled, without recalling at the same time the primary [{374}] response of seeing the tree. Can we recall the fact observed about the tree without at the same time seeing the tree "in the mind's eye"? Must we necessarily have an image of the tree when we recall the way the tree is constructed?
Since getting the general sensory appearance of the tree, and observing the way it is constructed, are two different responses, it seems quite conceivable that either fact should be recalled without the other; and no one doubts that the sensory appearance of the tree can be recalled without the other observed fact coming up along with it. But many authorities have held that the non-sensory fact could not be recalled alone; in other words, they have held that every recalled fact comes as a sensory image, or with a sensory image. Persons with ready visual imagery are of course likely to get a visual image with any fact they may recall. But persons whose visual imagery is hard to arouse say that they recall facts without any visual image. I who write these words, being such a person, testify that while I have been writing and thinking about that tree I have not seen it before my mind's eye.
It is true, however, that I have had images during this time--auditory images of words expressing the facts mentioned. Another individual might have had kinesthetic images instead of either visual or auditory. But can there be a recall of fact without any sensory image?
On this question, which has been called the question of "imageless thought", though it might better be called that of "imageless recall", controversy has raged and is not yet at rest, so that a generally accepted conclusion cannot be stated. But the best indications are to the effect, first, that vague and fleeting images, especially of the kinesthetic sort, are often present without being detected except by very fine introspection, some image being pretty sure to come up every few seconds when we are engaged in silent thought or [{375}] recall; but, second, that images are not present every second of the time, and that at the instant when a non-sensory fact is recalled it is apt to be alone.