In such cases there is always a measure of ocular and mental strain, which is often related (primarily as cause and secondarily as consequence) to some habitual error of refraction. It is true that the unperceived sensa belonging to persons in such a condition of strain are more or less faint and indistinct. Nevertheless they can be interpreted and perceived as appearances of external objects. The fact that they are not so interpreted and perceived is due to the condition of strain, which interposes a kind of barrier between the sensing eyes and the perceiving mind.
Now, sensa (as Dr. Broad has concluded after considering all the available evidence) always leave “mnemic traces” of the kind that may subsequently be revived and give rise to a memory-image. (Concerning the nature of these mnemic traces, or “engrams,” nobody as yet knows anything at all. They may be purely physical, or purely psychological, or simultaneously physical and psychological. The only thing we are justified in assuming about them is that they exist and can give rise, under favourable conditions, to memory-images.)
The experience of those who have undertaken a course of visual re-education adds further weight to the evidence for the hypothesis that sensa leave traces, and can therefore be remembered, even when, at the time, they were unperceived by the conscious mind. When people with defective vision take a flashing glance at some object, it often happens that they do not see it at all, or see it only as a dim blur. But on turning away and closing the eyes, they frequently discover that they have a memory-image of what was sensed. Often this image is so extremely tenuous, that they are hardly conscious of its being there at all.
But if they stop anxiously trying to bring it up into consciousness, and just make a random guess at its nature, it very frequently turns out that the guess is correct. From this we may conclude that it is possible for us to remember what we sensed, but did not see, provided always that the mental tensions associated with the conscious “I” are relaxed, either through hypnosis, or by other, less drastic methods.
This final proviso is of the highest practical significance. Strain, as I have said, erects a barrier between the sensing eyes and the perceiving mind. But if the strained organs of vision are relaxed, as they can be by palming, sunning and swinging, the barrier is lowered; and though it may not be possible at first to perceive what the sensing apparatus takes in, as it regards a given external object, it becomes increasingly easy, when the eyes are closed, to make a correct guess at the nature of the memory-image arising from the traces left by the act of sensing.
A good teacher can do much to help one in bringing up into consciousness the memory-images of what was merely sensed, not actually seen. Children, who are less self-conscious than their elders, respond particularly well to such a teacher’s suggestions and encouragements. For example, a child is shown some object, say a domino, or a printed letter, or word, from a distance at which he cannot normally see it. He is told to take a flashing glance at it, then close his eyes and “reach up into the air for it.” The child obeys the order quite literally, raises a hand, closes it on emptiness, then lowers it, opens it, looks into his palm and gives the correct answer, as though he were reading from notes.
After a certain amount of practice, the barrier between sensing and perceiving (always present in persons with defective vision) is so far lowered that unconscious vision (or the revival through memory of the traces left by sensing) gives place to conscious vision (or the perceiving of what is sensed in the same moment as it is sensed). In the early stages, there is generally a rather long interval between the act of sensing and the act of perceiving. Several seconds may elapse before the person can say what he has seen. The psychological barrier interposed by strain between the eyes and the mind has been lowered, indeed, but not yet completely eliminated. But as time goes on the interval is progressively shortened, until at last sensing and perceiving take place as they normally should, almost simultaneously.
Techniques of Flashing
Flashing, like swinging, can be practised during the activities of everyday life. For those whose vision is defective, the temptation to stare is always strong. Resist it, and acquire instead the habit of taking rapid glances at things, then averting or momentarily closing the eyes and remembering what was sensed. Billboards and shop-fronts provide excellent material on which to practice flashing, as one walks or is carried past them in car or bus. The mental attitude of one who is looking at the world in quick, brief flashes should be one of easy indifference.
Just as, while swinging, one lets the world go by without making any effort to get to know it in detail, so, while flashing, one should rid one’s mind of any over-anxious desire to see, and just be content to glance, first outwards at the physical object, then inwards at the memory-image of it. If the inward image corresponds with the outward object, as seen at a second and nearer glance, well and good. If it fails to correspond, but is merely a blur, that also is well and good. Nothing is so unfavourable to seeing as the competitive, prize-winning, test-passing spirit. Efforts on the part of the conscious “I” defeat their own object. It is when you stop trying to see that seeing comes to you.
Casual flashing should be supplemented by drills during periods specifically set aside for the purpose. The objects used in these drills should be fairly small, simple, clear-cut and familiar. Here, for example, are some effective procedures, in which use is made of a set of dominoes.
Relax the eyes by palming for a few moments; then pick up a domino at random, hold it out at arm’s length, pass the eyes across it in a quick glance and immediately close them. Even if the dots were not distinctly seen, it is probable that they were sensed, and that the sensing will have left a trace which can be revived as a memory-image. With the eyes still closed tell yourself what you remember to have made out of the upper half of the domino, then of the lower half. Open the eyes and, if necessary, bring the domino nearer for a verification of your guess. If the guess was right, well and good. If it was wrong, well and good. Take another domino and start again.
A more elaborate version of the same procedure is as follows. Take a dozen dominoes and stand them in a row along the edge of a table. Seat yourself in front of them at the limit of convenient seeing. Swing your eyes from left to right along the row, counting the dominoes as rapidly as you possibly can. (This sets the immobilized eyes and attention shifting at unaccustomed speed, and is a most salutary exercise in itself.) Then bring the eyes back to the first domino and, closing the lids, name the numbers in the upper and lower halves respectively. Open the eyes again and verify your guess. Then count the whole row once again and, glancing back to the second domino, flash, close, and name the numbers. Continue counting and flashing, until you reach the end of the line.
If your eyes are myopic, and it is hard to see at anything but short range, perform this drill for the first time within easy seeing distance; then move back and repeat. Familiarity with the dominoes will eliminate mental hazards and make the more distant seeing easier. It is possible in this way gradually to stretch the range of vision.
Where distant vision is easy, and difficulty is experienced only at the near point, this process should be reversed. Begin at some distance away; then move closer and go through the drill again.
CHAPTER XII, Shifting
Primarily designed to encourage mental and ocular mobility, the exercises described in the preceding chapters also serve, indirectly, to teach the art of central fixation. Having learnt, by means of them, to keep the eyes and attention in constant movement, and being therefore less subject than before to the vice of mental and physical staring, we may safely proceed to a somewhat more direct approach to central fixation. Even now, however, the approach will not be completely direct. Before attempting to become fully conscious of the fact that we always see one small area more distinctly than all the rest, we shall be well advised to take some simple lessons in the art of continuous and concentrated looking. Swinging encourages the eyes and mind to make movements of considerable amplitude, and flashing teaches rapidity of motion and interpretative reaction.
It is now necessary to teach ourselves small-scale shifting; for it is
