We present a cognitive developmental approach for a humanoid robot exploring its close environment in an interactive scenario, taking inspiration from the way infants learn about objects. The proposed approach allows to detect physical entities in the visual space, to create multi-view appearance models of these entities and to categorize them into robot parts, human parts and manipulated objects without supervision and without prior knowledge about their appearances. All information about the entities appearances and behaviour is incrementally acquired while the robot and its human partner interact with objects.