the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo.

the developing human organism from about 2 weeks after fertilization through the second month.

the developing human organism from 9 weeks after conception to birth.

agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm.

physical and cognitive abnormalities in children caused by a pregnant woman's heavy drinking. In severe cases, symptoms include noticeable facial misproportions.

decreasing responsiveness with repeated stimulation. As infants gain familiarity with repeated exposure to a visual stimulus, their interest wanes and they look away sooner.

biological growth processes that enable orderly changes in behavior, relatively uninfluenced by experience.

all the mental activities associated with thinking, knowing, remembering, and communicating.

a concept or framework that organizes and interprets information.

interpreting our new experience in terms of our existing schemas.

Development - adapting our current understandings (schemas) to incorporate new information.

the awareness that things continue to exist even when not perceived.

in Piaget's theory, the stage (from 2 to about 6 or 7 years of age) during which a child learns to use language but does not yet comprehend the mental operations of concrete logic.

the principle (which Piaget believed to be a part of concrete operational reasoning) that properties such as mass, volume, and number remain the same despite changes in the forms of objects.

in Piaget's theory, the preoperational child's difficulty taking another's point of view.

in Piaget's theory, the stage of cognitive development (from about 6 or 7 to 11 years of age) during which children gain the mental operations that enable them to think logically about concrete events.

in Piaget's theory, the stage of cognitive development (normally beginning about age 12) during which people begin to think logically about abstract concepts.

a disorder that appears in childhood and is marked by deficient communication, social interaction, and understanding of others' states of mind.

the fear of strangers that infants commonly display, beginning by about 8 months of age.

an emotional tie with another person; shown in young children by their seeking closeness to the caregiver and showing distress on separation.

an optimal period shortly after birth when an organism's exposure to certain stimuli or experiences produces proper development.

the process by which certain animals form attachments during a critical period very early in life.

a person's characteristic emotional reactivity and intensity.

according to Erik Erikson, a sense that the world is predictable and trustworthy; said to be formed during infancy by appropriate experiences with responsive caregivers.

all our thoughts and feelings about ourselves, in answer to the question, "Who am I?"

in psychology, the biologically and socially influenced characteristics by which people define male and female.

physical or verbal behavior intended to hurt someone.

the sex chromosome found in both men and women. Females have two of these; males have one. One chromosome from each parent produces a female child.

the sex chromosome found only in males. When paired with an X chromosome from the mother, it produces a male child.

the most important of the male sex hormones. Both males and females have it, but the additional levels in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty.

a set of expectations (norms) about a social position, defining how those in the position ought to behave.

a set of expected behaviors for males or for females.

our sense of being male or female.

the acquisition of a traditional masculine or feminine role.

the theory that we learn social behavior by observing and imitating and by being rewarded or punished.