Adults 20-25, 35-40, and 50-55 years old were examined on Sternberg's paradigm for rate of memory search. There were no differences between the two younger age groups in either overall performance or rate of memory scan, but the 50-55 year olds required approximately 50% more time per memory comparison than the two younger groups. Also, their intercepts were significantly greater.The effects of advancing age in humans are easy to chronicle at the physiological level, but they are less readily characterized or pinpointed in terms of psychological functioning. Tests of intelligence or mental abilities are quite molar. They are subject to differences in motivation and past experience. In the past decade, however, experimental psychology has made considerable progress in conceptually distinguishing and operationally measuring substages and processes involved in the more global tasks of perceiving, remembering, and recognizing. An examination of aging effects on these more elemental processes would appear desirable. Sternberg (1969), in a series of elegant experiments, has studied the rate of memory scan. The S is given a set of single digits to remember, with sets consisting of from one to five different digits . After committing these digits to memory, S is presented with a test digit. His task is to decide as quickly as possible whether the test digit is a member of the set. This task leads to remarkably uniform results. Reaction time (RT) not only increases with the size of the memory set but also the function is essentially linear for positive trials, where the test stimulus is among the memory set, and for negative trials, where it is not. Sternberg has found among his Ss that RT increases approximately 38-40 msec for each element in the memory set; he has interpreted his findings as indicating that , for this task, memory search is essentially serial in nature. That is, S compares the test stimulus successively with each member of the memory set, and each comparison operation requires approximately 38 msec. Since the slope of the function obtained for positive trials is essentially the same as for negative trials, it is further concluded that the search through memory is exhaustive. The essential nature of Bull. Psychon. Soc., 1973, Vol. 1 (4) these results has been confirmed in various laboratories.It was our purpose in this experiment to explore the possibility of differences in rate of memory scan as a function of advanced chronological age in human adults.
METHOD SubjectsAll Ss were male patients at the Danville VA Hospital, who voluntarily participated in the experiment. There were six Ss in each of the three age groups : 20-25, 35-40, and 50-55 years. In addition to the age criteria, the S s were selected on the basis of having a high degree of alertness, motivation, and freedom from drug medication.
Apparatus and StimuliTarget stimuli were presented in a three-field Scientific Prototype tachistoscope, and the luminance of the stimulus fields was 3.5 mL. Only the adaptation field containing a fixation cr...
