THE STIMULUS TRACE AND BEHAVIORAL INADEQUACY
Norman R. Ellis
This chapter is concerned with behavioral differences between normal and mentally defective humans. Primarily attention is directed to a class of behaviors viewed as dependent upon short-term memory, e.g., digit span or delayed reaction. The stimulus trace is invoked as an "explanatory" mechanism to account for immediate memory, and an individual differences construct is postulated to explain, in part, behavioral inadequacy. Short- term memory would be measured in seconds or minutes as contrasted with long-term memory measured by hours, days, or even years. Many commonly observed behaviors seem to depend upon a short-term storage mechanism; a telephone number is remembered only long enough to dial it, the specific words in a conversation may fade rapidly, or a particular card in a card game may not be remembered shortly after it has been played. Such events are described in the young child as "out of sight, out of mind" phenomena. This paper will develop the thesis that the individual with a subnormal central nervous system is characterized by an inadequacy in this function.
An ancillary hypothesis is that the apparent learning deficit in the subnormal organism is due to noncontinuity between events as a result of an impoverished stimulus trace. Even though differences between normal and subnormal organisms are adopted as a basis of speculation, an extension to individual intelligence differences, wherever they may occur, is not precluded.
The plan of the chapter is (1) to provide a brief review of the stimulus trace concept and some of the pertinent research in molar behavior theory, (2) to offer some speculation regarding a possible neurophysiological basis of short-term memory and how it may be affected by CNS pathology, (3) to adduce evidence from previous research in mental deficiency sup-