Parker and Gibson's developmental model of evolution of language and intelligence in early hominids is described and discussed; data from a comparative study of object manipulation in two apes and a human infant are reported; and, human ontogenic developmental retardation in locomotion is discussed in terms of its implications for the differential…

Reviews examples from the recent psychological literature relating to object orientation and constancy. The conclusion is reached that the attempt to separate the constancy and discrimination questions in an experimental design employing only a single dependent variable fails practically and theoretically. A theoretically more acceptable…