Longitudinal Stability of Adult Personality

Abstract

This chapter discusses the empirical evidence on the stability of personality. Personality researchers and theorists are realizing that the period of adulthood cannot be ignored, just as gerontologists have come to recognize that personality is central to the study of aging. Aging faces two formidable problems rarely encountered in other branches of psychology: (1) the independent variable, maturation cannot be manipulated. In consequence, only quasi-experimental designs can be used and these face well-known threats to their validity. (2) Aging is a process which requires decades to unfold. Researchers who wish to study changes must study the life span in segments or build upon the work of earlier researchers. The personality stability or change concerns normative shifts in the mean levels of personality. The fact that mean levels of most personality variables show little or no change with age does not necessarily imply that individuals do not change. Mean level stability cannot be observed even if all the individuals in the sample have undergone dramatic changes in the level of all personality variables. The major stability concerns the maintenance of rank order in individual differences. This form of stability is usually measured as a stability coefficient, a retest correlation based on re-administration of a measure after a period of years.