The Down's syndrome population presents a social quotient higher than its intelligence quotient, the main characteristic of its personality and because of the pronounced hypotony suffered by them, principally in the first years of life. This report shows the results of a study carried out about differential acquisitions of two groups of trisomy-21 babies, depending on the social reinforcement used with two variants: administered in physical interaction with the subject, and without interaction. According to the obtained data, we proved an upper level of acquisitions in the group that had received the reinforcement in the interaction.