| Term | Definition |
| conservation | the principle that properties such as mass, volume, and number remain the same despite changes in the forms of objects |
| object permanence | the awareness that things continue to exist even when not perceived |
| pre-operational stage | in Piaget's theory, the stage (from about 2 to 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 |
| sensorimotor stage | in Piaget's theory, the stage (from birth to about 2 years of age) during which infants know the world mostly in terms of their sensory impressions and motor activities |
| cognition | all the mental activities associated with thinking, knowing, remembering, and communicating |
| accommodation | adapting one's current understandings (schemas) to incorporate new information |
| assimilation | interpreting one's new experience in terms of one's existing schemas |
| schema | a concept or framework that organizes and interprets information |
| maturation | biological growth processes that enable orderly changes in behavior, relatively uninfluenced by experience |
| habituation | decreasing responsiveness with repeated stimulation |
| rooting reflex | a baby's tendency, when touched on the cheek, to turn toward the touch, open the mouth, and search for the nipple |
| fetal alcohol syndrome | physical and cognitive abnormalities in children caused by a pregnant woman's heavy drinking |
| teratogens | agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm |
| fetus | the developing human organism from 9 weeks after conception to birth. |
| zygote | the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo |
| developmental psychology | a branch of psychology that studies physical, cognitive, and social change throughout the life span |
| embryo | the developing human organism from about 2 weeks after fertilization through the second month |
| egocentrism | in Piaget's theory, the preoperational child's difficulty in taking another's point of view. (Myers Psychology 8e p. 150) |
| theory of mind | people's ideas about their own and others' mental states -- about their feelings, perceptions, and thoughts and the behavior these might predict |
| social clock | the culturally preferred timing of social events such as marriage, parenthood, and retirement |
| fluid intelligence | one's ability to reason speedily and abstractly; tends to decrease during late adulthood |
| longitudinal study | research in which the same people are restudied and retested over a long period |
| crystalized intelligence | one's accumulated acknowledge and verbal skills; tends fo increase with age |
| cross-sectional study | a study in which people of different ages are compared with one another |
| alzheimers disease | an irreversible, progressive brain disorder, characterized by the deterioration of memory, language, and eventually, physical functioning |
| menopause | the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines |
| intimacy | in Erikson's theory, the ability to form close, loving relationships; a primary developmental task in late adolescence and early adulthood |
| identity | one's sense of self; according to Erikson, the adolescent's task is to solidify a sense of self by testing and integrating various roles |
| attachment | an emotional tie with another person; shown in young children by their seeking closeness to the caregiver and showing distress on separation |
| critical period | an optimal period shortly after birth when an organism's exposure to certain stimuli or experiences produces proper development |
| imprinting | the process by which certain animals form attachments during a critical period very early in life |
| secondary sex characteristics | nonreproductive sexual characteristics, such as female breasts and hips, male voice quality, and body hair |
| primary sex characteristics | the body structures (ovaries, testes, and external genitalia) that make sexual reproduction possible |
| adolescence | the transition period from childhood to adulthood, extending from puberty to independence |
| puberty | the period of sexual maturation, during which a person becomes capable of reproducing |
| basic trust | 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 |
| self-concepts | central to the person's behavior, consists of a person's beliefs/feelings about himself at any given time |
| stranger anxiety | the fear of strangers that infants commonly display, beginning by about 8 months of age |
| menarche | the first occurrence of menstruation in a woman |
| formal operational stage | in Piaget's theory, the stage of cognitive development (normally beginning about age 12) during which people begin to think logically about abstract concepts |
| concrete operational stage | 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 |
| autism | a disorder that appears in childhood and is marked by deficient communication, social interaction, and understanding of others' states of mind |