Observations on adolescents and adults with profound hearing loss since birth or early childhood indicate a greater or lesser degree of immaturity, lack of empathy and stereotypy in conscience and social behaviour. Also noticed is a relatively shallow affective response, short-lived, labile and detached. The possible developmental relation of these traits to (a) absence of sound or (b) object deprivation is considered and the value of further studies of deaf infants pointed out.