Retention.
The retention of a mental impression in the memory depends very materially upon the clearness and depth of the original impression. And this clearness and depth, as we have previously stated, depend upon the degree of attention bestowed upon the original impression. Attention, then, is the important factor in the forming and recording of impressions. The rule is: Slight attention, faint record; marked attention, clear and deep record. To fix this fact in the mind, the student may think of the retentive and reproductive phases of memory as a phonographic record. The receiving diaphragm of the phonograph represents the sense organs, and the recording needle represents the attention. The needle makes the record on the cylinder deep or faint according to the condition of the needle. A loud sound may be recorded but faintly, if the needle is not properly adjusted. And, further, it must be remembered that the strength of the reproduction depends almost entirely upon the clearness and depth of the original impression on the cylinder; as is the record, so is the reproduction. It will be well for the student to carry this symbol of the phonograph in his mind; it will aid him in developing his powers of memory.
In this connection we should remember that attention depends largely upon interest. Therefore we would naturally expect to find that we remember interesting things far more readily than those which lack interest. This supposition is borne out in actual experience. This accounts for the fact that every one remembers a certain class of things better than he does others. One remembers faces, another dates, another spoken conversation, another written words, and so on. It will be found, as a rule, that each person is interested in the class of things which he most easily remembers. The artist easily remembers faces and details of faces, or scenery and details thereof. The musician easily recalls passages or bars of music, often of a most complicated nature. The speculator easily recalls the quotations of his favorite stocks. The racing man recalls without difficulty the "odds" posted on a certain horse on a certain day, or the details of a race which was run many years ago. The moral is: Arouse and induce an interest in the things which you wish to remember. This interest may be aroused by studying the things in question, as we have suggested in a preceding chapter.