Despite its importance for basic and applied psychology, only a few longitudinal studies have examined whether parental differential treatment (PDT) is a persistent or a transient phenomenon, these studies being confined to childhood or adolescence. Based on latent state-trait theory, the present study identified the amount of variance in three dimensions of perceived PDT in middle adulthood attributable to stable interindividual differences (trait variance) and to intraindividual changes (state variance). At two occasions of measurement (2 years apart), 709 middle-aged adults rated how often they and a sibling currently received parental recognition, nurture, and demand to assume filial responsibility. Tests of latent state-trait models for these three dimensions of PDT by structural equation modeling revealed that trait variance represented the largest proportion of the systematic variance in all observed indicators of perceived maternal and paternal differential treatment. Yet there was a considerable increase in state variance for the dimension of differential parental demand for assuming responsibility. Results are discussed with respect to the conditions accounting for the high overall stability of actual and/or perceived PDT in adulthood, and different approaches for determining their role are proposed.
