An Exploratory Study of Mental Organization in Senility.

Introduction THE fact that in the last few decades the proportion of the old and senile has been growing at an increasing rate and that this trend shows every likelihood of continuing has centred recent scientific interest on the psychological changes which take place in senility. As Dayton has shown (1940), Senile Dementia has now displaced Schizophrenia as the most common psychosis requiring hospital treatment, and many social problems are raised by the increasing average age of the population. Studies have been made of the ability of old people, shown by tests of intelligence, memory, motor co-ordination, imagination, and other functions. The work of Wechsler (1942), Miles (1933), Thorndike (1928), Sorenson (1933), Ruch (1923) and others has left little doubt that mental ability decreases with increasing age once adulthood has been reached. It has also been shown that this decrease takes place at different rates for different tests, and a ratio of the relatively slowly decreasing Vocabulary Test to the relatively quickly decreasing abstract type of intelligence test has been made into an index of senile deterioration (Babcock, 1941; Gilbert, 1935). While these facts may be regarded as established further points of interest remain to be investigated. It appears possible that, in addition to the quantitative differences observed between the abilities of the old and the young, qualitative differences also might be observed. Qualitative differences and changes which Piaget considers to contribute to the growth of intelligence may also become evident in its decline. An investigation into this problem has been reported elsewhere (Eysenck, 1945). Another problem will be dealt with in the present paper. None of the studies so far mentioned deal with the organization of the various abilities involved in the tests used; yet it seems reasonable to suppose that differences in organization should become apparent with advancing age. For instance, it has been reported that much higher intercorre-