| A | B |
|---|
| Nature | Refers to the influence of the genes that people inherit. |
| Nurture | Refers to environmental influences, beginning with the health and diet of the embryo’s mother and continuing lifelong, including family, school, community, culture, and society. |
| Critical Period | A time when something must occur for normal development, or the only time when an abnormality can occur. |
| Culture | The system of shared beliefs, conventions, norms, behaviors, expectations and symbolic representations that persist over time and prescribe social rules of conduct. |
| Developmental Theory | A systematic statement of principles and generalizations, providing a framework for understanding how and why people change over the life span. |
| Psychoanalytic Theory | A theory of human development that contends that irrational, unconscious drives and motives underlie human behavior. |
| Operant Conditioning | The learning process that reinforces or punishes behavior. |
| Behaviorism | A theory of human development that studies observable actions. |
| Social Learning Theory | A theory that emphasizes the influence of other people. Even without reinforcement, people learn via role models. |
| Cognitive Theory | A theory of human development that focuses on how people think. According to this theory, our thoughts shape our attitudes, beliefs, and behaviors. |
| Evolutionary Theory | When used in human development, the idea that many current human emotions and impulses are a legacy from thousands of years ago. |
| Microbiome | All of the microbes (bacteria, viruses, and so on) with all of their genes in a community. |
| Genome | The full set of genes that are the instructions to make an individual member of a certain species. |
| Dominant-recessive Pattern | The interaction of a heterozygous pair of alleles in such a way that the phenotype reflects one allele (the dominant gene) more than the other (the recessive gene). |
| Germinal Period | The first two weeks of prenatal development after conception, characterized by rapid cell division and the beginning of cell differentiation. |
| Age of Viability | The age (about 22 weeks after conception) at which a fetus might survive outside the mother’s uterus if specialized medical care is available. |
| Teratogen | An agent or condition, including viruses, drugs, and chemicals, that can impair prenatal development and result in birth defects or even death. |
| Low Birthweight | A body weight at birth of less than 2,500 grams (5½ pounds). |
| Very Low Birthweight | A body weight at birth of less than 1,500 grams (3 pounds, 5 ounces). |
| Extremely Low Birthweight | A body weight at birth of less than 1,000 grams (2 pounds, 3 ounces). |
| Apgar Scale | A quick assessment of a newborn’s health, from 0 to 10. Below 6 is an emergency—a neonatal pediatrician is summoned immediately. Most babies are at 7, 8, or 9—almost never a perfect 10. |
| REM Sleep | A stage of sleep characterized by flickering eyes behind closed lids, dreaming, and rapid brain waves. |
| Prefrontal Cortex | The area of the cortex at the very front of the brain that specializes in anticipation, planning, and impulse control. |
| Axon | A fiber that extends from a neuron and transmits electrochemical impulses from that neuron to the dendrites of other neurons. |
| Dendrite | A fiber that extends from a neuron and receives electrochemical impulses transmitted from other neurons via their axons. |
| Synapse | The intersection between the axon of one neuron and the dendrites of other neurons. |
| Neurotransmitter | A brain chemical that carries information from the axon of a sending neuron to the dendrites of a receiving neuron. |
| Limbic System | The parts of the brain that interact to produce emotions, including the amygdala, the hypothalamus, and the hippocampus. Many other parts of the brain also are involved with emotions. |
| Amygdala | A tiny brain structure that registers emotions, particularly fear and anxiety. |
| Hippocampus | A brain structure that is a central processor of memory, especially memory for locations. |
| Cortisol | The primary stress hormone; fluctuations in the body’s cortisol level affect human emotions. |
| Hypothalamus | A brain area that responds to the amygdala and the hippocampus to produce hormones that activate other parts of the brain and body. |
| Transient Exuberance | The great but temporary increase in the number of dendrites that develop in an infant’s brain during the first two years of life. |
| Sensation | The response of a sensory organ (eyes, ears, skin, tongue, nose) when it detects a stimulus. |
| Perception | The mental processing of sensory information when the brain interprets a sensation. |
| Fine Motor Skills | Physical abilities involving small body movements, especially of the hands and fingers, such as drawing or picking up a coin. ( |
| Gross Motor Skills | Physical abilities involving large body movements, such as walking and jumping. ( |
| Sensorimotor Intelligence | Piaget’s term for the way infants think—by using their senses and motor skills—during the first period of cognitive development. |
| Object Permanence | The realization that objects (including people) still exist when they can no longer be seen, touched, or heard. |
| Stunting | The failure of children to grow to a normal height for their age due to severe and chronic malnutrition. |
| Wasting | The tendency for children to be severely underweight for their age and height as a result of malnutrition. |
| Separation Anxiety | An infant’s distress when a familiar caregiver leaves; most obvious between 9 and 14 months. |
| Stranger Wariness | An infant’s expression of concern—a quiet stare while clinging to a familiar person, or a look of fear—when a stranger appears. |
| Temperament | Inborn differences between one person and another in emotions, activity, and self-regulation. It is measured by the person’s typical responses to the environment. |
| Insecure-Avoidant Attachment (Type A) | A pattern of attachment in which an infant avoids connection with the caregiver, as when the infant seems not to care about the caregiver’s presence, departure, or return. |
| Insecure-Resistant/Ambivalent Attachment (Type C) | A pattern of attachment in which an infant’s anxiety and uncertainty are evident, as when the infant becomes very upset at separation from the caregiver and both resists and seeks contact on reunion. |
| Secure Attachment (Type B) | A relationship in which an infant obtains both comfort and confidence from the presence of his or her caregiver. |
| Disorganized Attachment (Type D) | A type of attachment that is marked by an infant’s inconsistent reactions to the caregiver’s departure and return. |
| Self-Awareness | A person’s realization that he or she is a distinct individual whose body, mind, and actions are separate from those of other people. |
| Social Smile | A smile evoked by a human face, normally first evident in infants about 6 weeks after birth. |
