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Green and Bender continue their studies on double simultaneous tactile stimulation, extending it to a study of older persons. The subjects consisted of three hundred forty-two normal adults from forty to ninety-six years of age; those under sixty were compared with those over sixty. The method of double stimulation used in this investigation was the same as that employed in previous studies.
The results indicated a marked increase in the percentage of error with increasing age. Ninety-six percent of the subjects between sixty-five and ninety-six years of age gave incorrect responses on the initial trial and 54 percent continued to make errors during the entire series of ten tests. The errors consisted of extinction or displacement of one of the two stimuli; the face was dominant over the hand, and the foot dominant over the thigh. The persistent errors in older persons were similar to those demonstrated in normal children under six years of age, so that, just as with other measured functions of the nervous system, this function is most 'faulty' at the beginning and at the end of the life span. Most probably these phenomena in aged persons are a reflection of structural vascular alterations in the brain which accompany the normal aging process.