Primarily a feasibility study, the research reported is based on Eysenck's hypothesis that conditionability is a unitary factor related to introversion-extroversion and attention span. Thirty infants, representing a random sampling of race, sex, and socioeconomic background, were tested on three consecutive days at ages 3 months, 5 months, 9…

This study examines serial habituation in a sample of 54 infants aged 2, 3, and 4 months to determine whether age changes are partially a function of different "strategies" rather than simply different rates of habituation. The serial habituation hypothesis proposes that attention and habituation of attention proceed in order of the relative…