142 Memory as an Aid to Vision
ter on the Snellen test card is being regarded, the let ter improves, with or without the consciousness of the patient; because it is impossible to strain and relax at the same time, and if one relaxes sufficiently to remem ber the period, one must also relax sufficiently to see the letter, consciously or unconsciously. Letters on either side of the one regarded, or on the lines above and below it, also improve. When the patient is conscious of see ing the letters, this is very distracting, and usually causes him, at first, to forget the period; while with some patients, as already noted, the strain may return even before the letters are consciously recognized.
Thus patients find themselves on the horns of a dilemma. The relaxation indicated by the memory of a period improves their sight, and the things they see with this improved vision cause them to lose their re laxation and their memory. It is very remarkable to me how the difficulty is ever overcome, but some patients are able to do it in five minutes or half an hour. With others the process is long and tedious.
There are various ways of helping patients to deal with this situation. One is to direct them to remember the period while looking a little to one side of the test card, say a foot or more; then to look a little nearer to it, and finally to look between the lines. In this way they may become able to see the letters in the eccentric field with out losing the period; and when they can do this they may become able to go a step farther, and look directly at a letter without losing control of their memory. If they cannot do it, they are told to look at only one part of a letter-usually the bottom-or to see or imagine the period as part of the letter, while noting that the rest of the letter is less black and less distinct than the part