— This paper proposes a novel model which enables a humanoid robot infant to discover other individual (e.g. human parent). In this work, the authors define “other individual” as an actor which can be predicted by a self-model. For modeling the developmental process of discovering ability, the following three approaches are employed. (i) Projection of a selfmodel for predicting other individual’s actions. (ii) Mediation by a physical object between self and other individual. (iii)