Responses of 4month-old infants to hidden people and objects were investigated with equated task demands. Twenty-one Cmonth~dd infants were administered a combined task, in which they were shown a sounding stimulus that continued to sound after hiding, an auditory task, in which sound was the only m e of information about the position of the object in space, and a vision task, in which a silent stimulus was shown to the infants prior to hiding. Five infant behaviours were coded: reaching, gazing, body movements, vocalizations and smiles. The infants reached significantly more for hidden objects than for people, to whom they vocalized instead. They further smiled, and moved their bodies more towards their invisible mother than to the other stimuli. Thus infants responded differentially to people and objects whether the stimuli were soundless (so that there was no cue to their presence) or not. This suggested that infants appreciated (a) that an object had been hidden; (b) this object was either animate or inanimate; and (c) different procedures were appropriate for the retrieval of, or for interacting with animate and inanimate objects. Discussion centres on the underlying representational system that allows for such appreciation.Key words: Object search, person search, multimodal.A question frequently addressed by Piaget (1954) concerned the developing understanding of the animate and inanimate distinction. As adults, we distinguish between people and things while knowing that all objects share certain fundamental properties. Both animate and inanimate objects have physical properties (size and shape), but only people act independently, have feelings and intentions. If we want to acquire knowledge about the two classes, we communicate with people and act on objects (Bretherton et al