Recent research has shown that preschool children tend to preferentially allocate resources to rich than to poor others. The findings that young children tend to perpetuate inequalities are puzzling given classical developmental theories that largely focused on the emergence of equality and equity in childhood. In this review, we first sketch the early ontogeny of fairness concerns before providing an overview on studies reporting perpetuation of inequality in young children. We review four classical theories (Piaget, Kohlberg, Damon, Social Domain Theory) and discuss how they would account for this phenomenon. We then introduce four recent theoretical models that directly speak to the underlying psychological processes; the affective preference model, the reciprocity-based strategic model, the numerical matching model, and the normative model. We highlight the key tenets of each model, their relation to other developmental processes, and the strength of the empirical evidence. From each model, we derive specific hypotheses. Finally, in an integrative section we discuss how the models might relate to each other, highlight connections to other research areas, and present avenues for future research.

ObjectiveOne of the most challenging issues in the pediatric obsessive–compulsive (OC) disorder field is to differentiate pathological OC symptoms from the phenotypically similar normative rituals/routines that characterize normal childhood development. Given their similarities, it can be questioned whether both constructs reflect two qualitatively distinct behavioral expressions of different etiological factors or rather reflect two diverse manifestations of one single continuum (cfr. the continuity hypothesis). MethodThis paper aims to improve our understanding of the relation between normative childhood rituals/routines and OC symptoms in two ways. First, the continuity hypothesis was investigated by systematically reviewing current evidence on this association, using various databases (Web of Science Core Collection, MEDLINE/PubMed, and SciELO Citation Index) from 1950 until February 1, 2019 (registration number: CRD42019121293). Second, based on this systematic review, an integrative conceptual model was developed describing this relation from different perspectives on sources of influence. ResultsThe literature search initially revealed 2122 hits, with 114 full-texts being assessed for eligibility. After applying several selection criteria, 18 studies were included in the review. The results generally support the continuity hypothesis and reveal important etiological factors at different levels of behavioral analysis, including the phenotypic (anxiety), neurobiological and genetic level. Also age and the presence of other disorders appeared to be important factors in evaluating the level of normality. ConclusionWe provide a conceptual framework to inform future research aimed at improving the understanding of the relationship between normative rituals/routines and pathological OC symptoms. Conceptual implications are discussed and clinical recommendations are given to improve early identification and differentiation.