a gradual increase in the capacity to experience, express, and interpret the full range of emotions and in the ability to cope with them appropriately. For example, infants begin to smile and frown around 8 weeks of age and to laugh around 3 or 4 months, and older children begin to learn that hitting others is not an acceptable way of dealing with anger. Expressions of delight, fear, anger, and disgust are evident by 6 months of age, and fear of strangers from 8 months. Expressions of affection and jealousy are seen between 1 and 2 years of age, and expressions of rage in the form of temper tantrums appear a year or so later. Cortical control, imitation of others, hormonal influences, home atmosphere, and conditioning play major roles in emotional development. Also called affective development.