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Infancy and Childhood

Prenatal Development


Babies come into the world with many innate abilities, or abilities that are present from birth. At birth, they possess motor reflexes such as the sucking reflex and the grasping reflex. Newborns can also hear, smell, touch, taste, and see, and these sensory abilities develop quickly.

Motor Development

Motor development also progresses quickly. Motor development is the increasing coordination of muscles that makes physical movements possible. Developmental norms tell us the median age at which babies develop specific behaviors and abilities. Babies often deviate a fair amount from these norms.

Researchers used to think motor skill development could be explained mostly by maturation, genetically programmed growth and development. According to this view, babies learn to sit up, pull themselves to a standing position, and walk at particular ages because they are hard-wired that way. However, recent research suggests that motor development isn’t just a passive process. Although maturation plays a large role, babies also actively develop motor skills by moving around and exploring their environments. Both maturation and experience influence motor development.

Cultural differences also affect how quickly motor skills develop, although the timing and sequence of early motor skill development remains similar across all cultures.

Example: In cultures where babies receive early training in sitting up, standing, and walking, they develop these skills earlier. Conversely, in other cultures, mothers carry babies most of the time, and babies develop these skills later.


Some babies have fussy personalities, while others have chirpy or quiet natures. These differences result from temperament, the kind of personality features babies are born with. Researchers generally agree that temperament depends more on biological factors than on environment. In the 1970s, Alexander Thomas and Stella Chess, two researchers who study temperament, described three basic types of temperament: easy, slow to warm up, and difficult. In their research, 40 percent of the children were easy, 15 percent were slow to warm up, and 10 percent were difficult. The remaining 35 percent of the children displayed a mixture of these temperaments:

  • Easy children tend to be happy and adapt easily to change. They have regular sleeping and eating patterns and don’t upset easily.
  • Slow-to-warm-up children tend to be less cheerful and less adaptable than easy children. They are cautious about new experiences. Their sleeping and eating patterns are less regular than those of easy children.
  • Difficult children tend to be glum and irritable, and they dislike change. Their eating and sleeping patterns are irregular.


Attachment is the close bond between infants and their caregivers. Researchers used to think that infants attach to people who feed them and keep them warm. However, researchers Margaret and Harry Harlow showed that attachment could not occur without contact comfort. Contact comfort is comfort derived from physical closeness with a caregiver.

The Harlows’ Baby Monkeys

The Harlows raised orphaned baby rhesus monkeys and studied their behavior. In place of its real mother, each baby monkey had two substitute or surrogate mothers. One “mother” had a head attached to a wire frame, warming lights, and a feeding bottle. The other “mother” had the same construction except that foam rubber and terry cloth covered its wire frame. The Harlows found that although both mothers provided milk and warmth, the baby monkeys greatly preferred the cloth mother. They clung to the cloth mother even between feedings and went to it for comfort when they felt afraid.

Responsive Mothering

Psychologist Mary Ainsworth and her colleagues found that attachment happens through a complex set of interactions between mothers and infants. The infants of sensitive, responsive mothers have stronger attachments than the infants of insensitive mothers or mothers who respond inconsistently to their infants’ needs. However, an infant’s temperament also plays a role in attachment. Difficult infants who fuss, refuse to eat, and sleep irregularly tax their mothers, which makes it hard for the mothers to be properly responsive.

Attachment Styles

Ainsworth devised an experiment called the Strange Situation in order to study attachment behavior. She asked each mother in the sample to bring her infant to an unfamiliar room that contained various toys. After the mother and infant had spent some time in the room, a stranger entered the room and tried to play with the infant. A short while later, the mother left the room, leaving the infant with the stranger. Then the mother returned to the room, and the stranger left. A little later, the mother left the room again, briefly leaving the infant alone. Finally, the mother returned to the room.

Based on her observations of infants’ behavior in the Strange Situation, Ainsworth described three types of attachment patterns:

  1. Secure attachment: Most infants in the sample had a secure attachment to their mothers. These infants expressed unhappiness when their mothers left but still played with the stranger. When their mothers returned, the infants looked happy. The infants displayed greater attachment to their mothers than to the stranger.
  2. Anxious-ambivalent attachment: Some infants showed a type of insecure attachment called an anxious-ambivalent attachment. These infants became upset when their mothers left but resisted contact with their mothers when they returned.
  3. Avoidant attachment: Other infants showed a type of insecure attachment called an avoidant attachment. These infants didn’t seem upset when their mothers left and avoided their mothers when they returned. Researchers did not see a significant difference in the way these infants treated their mothers and the stranger.
Culture and Attachment Style

Culture can influence attachment style because different cultures have different child-rearing practices. Ainsworth’s research in the United States showed that most of her white, middle-class sample of infants had a secure attachment to their mothers. However, in Germany, where parents encourage independence from an early age, a much higher proportion of infants display an avoidant attachment, according to Ainsworth’s classification. In Japan, where infants rarely separate from their mothers, the avoidant style is nonexistent, although a higher proportion of anxious-ambivalent attachments occurred than in the United States.

Separation Anxiety

Whether they are securely attached or not, most babies do experience separation anxiety. Separation anxiety is the emotional distress infants show when they separate from people to whom they are attached. Separation anxiety typically begins at about six to eight months of age and reaches peak intensity when an infant is about fourteen to eighteen months old.

Gender Development

Sex isn’t the same as gender. Sex refers to a biological distinction between males and females. An example of sex difference is the timing of puberty. Because of biological processes, girls’ sexual organs mature before those of boys. Gender refers to a learned distinction between masculinity and femininity. An example of gender difference is girls’ and boys’ attitudes toward dolls. Very early on, American society teaches boys that playing with dolls is considered a girlish thing to do. Gender stereotypes are societal beliefs about the characteristics of males and females.

Gender Differences

Some gender differences exist, although certainly not as many as stereotypes suggest. For example, starting in preschool, gender differences arise in play behavior. Boys prefer playing with boys and girls with girls. Boys prefer to play with boyish toys like trucks and girls with girlish toys like dolls. Different people give different answers for why this is so:

  • Researchers who emphasize biological differences between the sexes say that these preferences arise from biological factors such as genetics and evolution, prenatal hormones, or brain structure.
  • Researchers who focus on cognitive development believe that these preferences exist because boys and girls develop different gender schemas or mental models about gender.
  • Researchers who study learning think that environment produces these preferences. They point out that almost from the moment of birth, girls and boys receive different treatment. Gender preferences, these researchers say, simply reflect what society teaches children about gender.

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