Two studies tested whether 12- and 24-month olds' self-knowledge differed from their knowledge of others (mother or inanimate object), or whether toddlers' knowledge of persons (self and mother) differed from knowledge of objects. Results showed that 12-month olds were more sensitive than older toddlers to perceptual features of objects. Data were interpreted according to U. Neisser's (1988, 1991) distinction between ecological and interpersonal self. (DR)