Abstract: | When presented with two-element geometric stimuli, with one element enclosed within the other, infants under 2 months of age do not appear to detect the internal element and fail to respond to a change in that element. Infants over 2 months of age experience no difficulty in this respect. However, it is established that this “externality effect” does break down under certain circumstances, for example, where there is independent modulation of the internal element. Evidence is presented which appears to run counter to explanations of this effect in terms of information processing limitations, capture of attention by dominant salience, or level of arousal. An alternative explanation based on figure-ground organization is given partial support. |