Investigation of amnesic defects by progressive prompting.

There appears to be a growing tendency in the recent literature to ascribe the defects of memory seen in organic amnesic states to difficulties of activation (recall) rather than to those of registration or organization of impressions. This was foreshadowed by the clinical observations of such workers as Korsakoff (1889) and Bonhoeffer (1904), who remarked that amnesic patients might be able to find their way around the wards in which they lived, although they would deny, as soon as removed from these surroundings, that they had ever been inside a hospital ward. Although Gillespie (1937) argues from such observations that "the continuityof personal identity and mechanical memory are separatephenomena", the evidence can also be interpreted in terms of inertia or inaccessibility of those memories which are not reinforced by perceptual stimuli. Such an interpretation is supported by the observations of Gruinthal (1923) who found that much past material for which a patient is ostensibly amnesic may be recovered if questions are put to him in such a way as partially to reinstate the forgotten situations. Experiments on learning conducted by Brodmann (1904) and Gregor (1909) with amnesic patients also demonstrated that the apparently forgotten leaves traces which may be seen in a saving on the number of repetitions required for re-learning. Schilder (1942) concludes from a consideration of this evidence that " a psychic experience once conceived does not completely disappear from the psychic field" but "becomes paler in the course of time... It can be evoked when the immediate situation demands it". More recent experimental confirmation of this hypothesis has been forthcoming from studies of amnesia following electric convulsion treatment (E.C.T.). Mayer-Gross (1943) and Zubin (1948) both report that recognition is significantly less severely affected by this treatment than recall, and Janis (1950) further found that past experiences which patients cannot recall when first asked about them may be recovered if the patients are allowed the opportunity to " work on " their memory. Recent animal experiments carried out by Kltuver and quoted by Lashley (1950) point in the same direction and have led the latter to define amnesia as " a lowered level of vigilance, a greater difficulty in activating the organized patterns of traces". One difficulty in assessing the clinical evidence in this field is the lack of systematic comparison between the availability of memory in normal and abnormal subjects. A study of the availability of memory in general, in relation to the total amount of material remembered, is necessary before organic amnesia can be considered solely in terms of inertia of mental functions. An experimental technique has been designed in a preliminary attempt to meet this need, and the result of its application in a small group of subjects is described in the present paper.