Memory (Part 4)

Kuhlmann also found changes in recall according to the lapse of time between hearing the material and testing for recall, which he did after one, three and six weeks. The greatest changes occurred between the immediate and the second recall.

There was a striking transformation from the immediate to the last recall, in both the manner of recall and the final result, in the auditory imagery of the words.

Visual imagery was not constant in immediate recall; it preceded the auditory in most cases in the last recall, and increased in amount, so that the visual imagery alone presented the whole scene and event. The general clearness and vivacity of the visual imagery remained about constant throughout the several recalls.

The total amount recalled in auditory terms decreased markedly, sometimes leaving only a sentence or two that could be recalled after six weeks' interval. The fragmentary character of the recall, however, did not increase much.

There were progressive stages in the quality of auditory imagery: first, the voice was imaged in its individual quality; next it was imaged merely as a bass or tenor; after that it appeared in a somewhat characterless fashion; and finally there was no definite or complete auditory imagery at all before the words were formulated and stated in the recall.

The processes involved in memorizing also changed. At first, attention was divided between actual sounds and visual imagery. The first repetition or two brought with them the process of naming sounds and imitating them. During further repetitions visual imagery and naming quickly disappeared, and motor processes of imitation increased for a while, but tended, finally, to drop out.

Kuhlmann had his subjects recall sounds in a semi-passive way, without making any effort in the direction of detail or vividness. In 53% visual imagery appeared first, in 15% naming the subject of recall came first, and in 8% motor processes came first. Visual imagery preceded auditory imagery in 55%, the name preceded the auditory image in 24% and motor processes preceded auditory imagery in 13%.

Visual imagery was described as consisting of the things that produced the sounds (although attention to visual imagery for purposes of recalling details proved detrimental to recall); of the things going through the motions they would make in producing the sounds; or of visual sound analogues, consisting of arbitrary forms, sometimes including colors, whose characteristics were patterned after the characteristics of the sounds.

The motor processes which were used in imitating the sounds were inseparably connected with the effort to recall the sound vividly and minutely.

The auditory imagery was very fragmentary, and could not usually be directly controlled voluntarily, but only through motor processes, or, in some instances, through visual imagery.

Sleep-learning observers have pointed out that some time periods are more favorable to learning and some less. Edward Van Ormer conducted an investigation to determine the best time for study in terms of how well we remember later what we have learned. He examined retention after intervals of sleep and waking and found that on the whole recall was most efficient after sleep.

Other investigators he reported on came to the same general conclusion; Jenkins and Dallenback said that "forgetting is not so much a matter of the decay of old impressions and associations as it is a matter of interference, inhibition, or obliteration of the old by the new." Heine said improved memory resulting from "sleeping on" the learned material was due to the elimination of the retroactive inhibition produced by the day activities which normally follow learning.