| zygote | fertilized egg; enters 2 week period of rapid cell division |
| embryo | developing human organism from about 2 weeks after fertilization through the second month |
| fetus | developing human organism from 9 weeks after conception to birth |
| teratogens | agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm |
| fetal alcohol syndrome (FAS) | physical and cognitive abnormalities in children caused by a pregnant woman's heavy drinking; causes facial misproportions |
| rooting reflex | baby's tendency, when touched on the cheek, to turn toward the touch, open the mouth, and search for the nipple |
| habituation | decreasing responsiveness with repeated stimulation; visual stimulus wanes and they look away sooner |
| maturation | biological growth processes that enable orderly changes in behavior |
| schema | concept or framework that organizes and interprets information |
| assimilation | interpreting one's new experience in terms of one's existing schemas (149) |
| accommodation | adapting one's current understandings (schemas) to incorporate new information |
| cognition | all the mental activities associated with thinking, knowing, remembering, and comunicating |
| sensorimotor stage | in Piaget's theory, stage (from birth to 2 years) during which infants know the world mostly in terms of sensory impressions |
| object permanance | awareness that things continue to exist even when not perceived |
| preoperational stage | Piaget's theory, the stage (2 to 6/7 years of age) during which a child learns to use language but does not yet comprehend the mental operations of concrete logic |
| conservation | principle (a part of Piaget's concrete operational reasoning), that properties such as mass, volume, and number remain the same despite changes |
| egocentrism | in Piaget's theory, the preoperational child's difficulty taking another's point of view |
| theory of mind | people's ideas about their own and other's mental states |
| autism | disorder that appears in childhood and is marked by deficient communication, social interaction, and understanding of others' states of minds |
| concrete operation | in Piaget's theory, stage of cognitive development (6/7 to 11 years of age) during which children gain the mental operations that enable them to think logically about concrete events |
| formal operational stage | Piaget's theory, stage of cognitive development (beginning at 12) during which people begin to think logically about abstract concepts |
| stranger anxiety | fear of strangers that infants commonly display, beginning by about 8 months of age |
| attachment | emotional tie with another persion |
| critical period | optimal period shortly after birth when an organism's exposure to certain stimuli or experiences produces proper development |
| imprinting | process by which certain animals form attachments during a critical period very early in life |
| basic trust | according to Erik Erickson, a sense that the world is predictable and trustworthy |
| self-concept | sense of one's identity and personal worth |
| adolescence | transition period from childhood to adulthood, extending from puberty to independence |
| puberty | period of sexual maturation, during which a person becomes capable of reproducing |
| primary sex characteristics | body structures (ovaries, testes, external genitalia) that make sexual reproduction possible |
| secondary sex characteristics | nonproductive sexual characteristics, such as female breasts and hips, male voice quality, and body hair |
| menarche | first menstrual period |
| identity | one's sense of self |
| intimacy | Erikson's theory; ability to form close, loving relationships |
| menopause | time of natural cessation of menstruation |
| Alzheimer's disease | progressive and irreversible brain disorder characterized by gradual deterioration of memory, reasoning, language, and physical functioning |
| cross-sectional study | study in which people of different ages are compared with one another |
| longitudinal study | research in which the same people are restudied and retested over a long period |
| crystallized intelligence | one's accumulated knowledge and verbal skills; tends to increase with age |
| fluid intelligence | one's ability to reason speedily and abstractly; tends to decrease with age |
| social clock | the culturally preferred timing of social events such as marriage, parenthood, and retirement |