Basic emotions are those that can be directly inferred from facial expressions, such as happiness, interest, surprise, fear, anger, sadness, and disgust. Happiness binds parent and baby and fosters the infant's developing competence. Laughter first appears around three to four months in response to active stimuli. Anger is expressed in the first few months of life when babies cry in response to unpleasant stimuli. Actually, the negative emotions appear before the positive ones in most newborns.
Fear rises during the second half of the first year.
Stranger anxiety is an expression of fear in response to unfamiliar adults. It depends on the infant's temperament, past experiences with strangers, and the situation in which the baby and stranger meet. Between seven and ten months, infants perceive facial expressions as organized patterns, and they can match the emotional tone of voice with the appropriate face of a speaking person. Social referencing occurs when an infant relies on a trusted person's emotional reactions to decide how to respond in uncertain situations. Social referencing provides infants with a way to learn about the environment through indirect experience.