The benefits of need satisfaction depend on their relative importance for people with a unidimensional identity: an idiographic analysis

Self-determination theory proposes that the satisfaction of basic psychological needs is equally beneficial for everyone – the Universal Hypothesis. Equally, there are intra-individual differences in how the satisfaction of differentially important needs might be differentially beneficial, which we term the Intra-individual Hypothesis. We aimed to reconcile these positions. Across four cross-sectional studies (ns = 300 rock climbers, 323 sportspeople, 394 UK and Chinese adults, 320 UK adults), we investigated the needs of individuals with varying dimensions to their identity, and their motivation and self-esteem. In Studies 1, 2, and 4, when individuals strongly related their sense of identity to investment in a specific activity, the association between need satisfaction and self-esteem (and motivation in Studies 1–2) depended on their intra-individual need importance, supporting the Intra-individual Hypothesis. In Studies 3 and 4, for individuals with a multidimensional identity, the association between need satisfaction and self-esteem did not depend on the importance of each need, supporting the Universal Hypothesis. The satisfaction of basic psychological needs is not always uniform in its link with motivation and well-being. The degree to which individuals have a unidimensional or multidimensional self-concept appears fruitful in predicting the relative value of the Universal Hypothesis and the Intra-individual Hypothesis.