Emotional self-regulation refers to the strategies used to adjust emotional states to a comfortable level of intensity. By the end of the first year, babies' ability to move around permits them to regulate feelings more effectively by approaching or retreating from various stimuli. American culture encourages positive feelings more than negative ones. Infant boys get more training in hiding their unhappiness than do girls. Growth in representation and language permits toddlers to describe their emotions.
Temperament refers to stable individual differences in quality and intensity of emotional reaction.
Thomas and Chess initiated the New York Longitudinal Study which was a comprehensive examination of temperament. Results indocate that tmperament is somewhat predictive of psychological adjustment, and parenting practices can modify children's emotional styles. Temperament is usually assessed through parent interviews and questionnaires, behavior ratings by medical professionals or caregivers, and direct researcher observation. The easy child has a temperament such that he quickly establishes regular routines in infancy, is generally cheerful, and adapts easily to new experiences. The difficult child is irregular in daily routines, is slow to accept new experiences, and tends to react negatively and intensely.