ABSTRACT
At about 4 to 5 months of age, at the peak of symbiosis, behavioral phenomena seem to indicate the beginning of the first subphase of separation-individuation, namely differentiation. S. Freud emphasized that internal perceptions are more fundamental and more elementary than external ones. Greeriacre's patterning of "coreness" is not available to observational research, but behaviors which, through the mutual mirroring mechanism, serve the demarcation of the self from the "other" are amenable to observational research. The "hatching process" is a gradual ontogenetic evolution of the sensorium—-the perceptual-conscious system—which enables the infant to have a more permanently alert sensorium whenever he is awake. Observing the infants in our set-up, we came to recognize at some point during the differentiation subphase a certain new look of alertness, persistence and goal-directedness. The baby begins comparative scanning. He becomes interested in "mother" and seems to compare her with "other," the unfamiliar with the familiar, feature by feature.
