Harold E. Jones

Development of Mental Functions

THE chief problems and research trends in the study of mental development were defined, as of 1950, in the previous growth and development numbers of the REVIEW (46, 107). Current studies have shown a sustained interest in each of these topics, with special attention to certain critical issues. Renewed effort is being directed toward the analysis of socio-economic factors in relation to intelligence and achievement. Age changes in mental abilities, and responses to the same tasks at different ability levels, have continued to receive marked emphasis. Some interest in the effect of glutamic acid on intellectual development was reflected in the previous review, and research on this relationship has gained momentum; however, in view of the negative results of the majority of these studies, further inquiry in this particular area may be expected to diminish. The examination of mental-physical relationships has continued; of particular note in this connection are recent studies on the effect of prenatal and natal conditions on later mental status. If we are to judge by the number of publications, the relationship of interests to abilities is no longer a prominent topic, but much still remains to be done in analyzing the role of emotional factors in mental functioning, and studies in this area have opened a number of promising leads. Differential fertility is also a topic of concern; the publication of several major reports has raised new problems which require additional study, particularly in relation to social trends in age at marriage and in family size. Infant Tests

Mental Development in Infancy and Childhood and Mental Abilities in Adult Life

EARLIER reviews of mental development in this journal (39, 56, 121) focused primarily on the period of childhood and adolescence. Longitudinal studies are now beginning to yield information on age changes later in the life span of individuals first tested in childhood or adolescence. Therefore it seems appropriate to consider both types of studies in this review. Research workers continue to show an active interest in the consistency of test performance at different ages and in factors related to change in test performance. The effect of environmental variables on mental development constituted the subjectmatter of a review by Jones (65), in which over 300 of the major studies in the area were considered. Other topics which received attention recently include the role of emotional and motivational factors and the problem of the extent to which IQ changes represent true changes in relative standing or are attributable instead to test construction, test standardization, or other psychometric factors.

Chapter II: Mental Development in Infancy and Childhood and Mental Abilities in Adult Life

JCiARLiER reviews of mental development in this journal (39, 56, 121) focused primarily on the period of childhood and adolescence. Longitudinal studies are now beginning to yield information on age changes later in the life span of individuals first tested in childhood or adolescence. Therefore it seems appropriate to consider both types of studies in this review. Research workers continue to show an active interest in the consistency of test performance at different ages and in factors related to change in test performance. The effect of environmental variables on mental development constituted the subjectmatter of a review by Jones (65) , in which over 300 of the major studies in the area were considered. Other topics which received attention recently include the role of emotional and motivational factors and the problem of the extent to which IQ changes represent true changes in relative standing or are attributable instead to test construction, test standardization, or other psychometric factors. Group as well as individual differences were examined in numerous studies. Especially prominent are the analyses of test performance of institutional and defective children and studies of various socioeconomic and ethnic groups. Darcy (30) published a review dealing with research on bilingual subjects. Many investigations were made of the differential responses of groups with different physical and mental disorders. Milner (83) reviewed the literature bearing on the intellectual changes resulting from temporal-lobe damage. Altho no striking gains have been made in the methodology of research on mental development, existing methods and theory continue to provide scope for vigorous research activity. Research on mental development of the infant still tends to be directed at determining the predictive value of tests given in infancy. Macfarlane (76) , summarizing one of the longitudinal studies at the University of California, drew implications as to the use of infant tests in adoption. Prospective parents whose expectations would be met only by a child of superior ability would do well to delay adoption until a child has reached an age, beyond infancy, when prediction from tests can offer somewhat greater promise of accuracy. Griffiths (49) developed a new test for the first two years, standardized on a sample designed to be representative of the London population.