Twenty infants, 12 weeks of age, were subjects in an experiment to test the effects of maternal behavior on their perceptual-cognitive development. Each mother and child were observed in a controlled naturalistic setting, every 10 seconds their various behaviors were recorded, and then the mother was interviewed. During an experimental session the infant was placed in a reclining seat with a matrix panel on which stimuli were presented 18 inches in front of him. The mother sat to the rear and side of the infant. Response decrement was positively correlated with the amount of touching, looking, holding, and smiling the mother exhibited and negatively correlated with the amount of time the mother was reading. Higher frequencies of maternal response were associated with greater response decrement. Data consistently indicate there is positive correlation between maternal response to infant behavior and the cognitive development of the infant as measured by response decrement. Helplessness or control is a learned motive and has important consequences for subsequent perceptual-cognitive development. Maternal behavior stimulates within the infant the expectancy that his behavior can affect his environment and motivates him to produce and utilize behaviors and skills not reinforced in his past experience. (DO)