← Chapter 9: Lifespan Development Export Options Alphabetize Word-Def Delimiter Tab Comma Custom Def-Word Delimiter New Line Semicolon Custom Data Copy and paste the text below. It is read-only. Select All Developmental Psychology The branch of psychology that studies how people change over the lifespan. Chromosome A long, threadlike structure composed of twisted parallel strands of DNA; found in the nucleus of the cell. DNA (Deoxyribonucleic Acid) The chemical basis of heredity; carries the genetic instructions in the cell. Gene The basic unit of heredity that directs the development of a particular characteristic; the individual unit of DNA instructions on a chromosome. Genotype The underlying genetic makeup of a particular organism, including the genetic instructions for traits that are not actually displayed. Phenotype The observable traits or characteristics of an organism as determined by the interaction of genetics and environmental factors. Dominant Gene In a pair of genes, the gene containing genetic instructions that will be expressed whether paired with another dominant gene or with a recessive gene. Recessive Gene In a pair of genes, the gene containing genetic instructions that will not be expressed unless paired with another recessive gene. Sex Chromosomes Chromosomes designated as X or Y that determine biological sex; the 23rd pair of chromosomes in humans. Sex-Linked Recessive Characteristics Traits determined by recessive genes located on the X chromosome; in males, these characteristics require only one recessive gene to be expressed. Prenatal Stage The stage of development before birth; divided into the germinal, embryonic, and fetal periods. Germinal Period The first two weeks of prenatal development. Embryonic Period The second period of prenatal development, extending from the third week through the eighth week. Teratogens Harmful agents or substances that can cause malformations or defects in an embryo or fetus. Fetal Period The third and longest period of prenatal development, extending from the ninth week until birth. Temperament Inborn predispositions to consistently behave and react in a certain way. Attachment The emotional bond that forms between an infant and caregiver(s), especially his or her parents. Comprehension Vocabulary The words that are understood by an infant or child. Production Vocabulary The words that an infant or child understands and can speak. Sensorimotor Stage In Piaget's theory, the first stage of cognitive development, from birth to about age 2; the period during which the infant explores the environment and acquires knowledge through sensing and manipulating objects. Object Permanence The understanding that an object continues to exist even when it can no longer be seen. Preoperational Stage In Piaget's theory, the second stage of cognitive development, which lasts from about age 2 to age 7; characterized by increasing the use of symbols and prelogical thought processes. Symbolic Thought The ability to use words, images, and symbols to represent the world. Egocentrism In Piaget's theory, the inability to take another person's perspective or point of view Irreversibility In Piaget's theory, the inability to mentally reverse a sequence of events or logical operations. Centration In Piaget's theory, the tendency to focus, or center, on only one aspect of a situation and ignore other important aspects of the situation. Conservation In Piaget's theory, the understanding that two equal quantities remain equal even though the form or appearance is rearranged, as long as nothing is added or subtracted. Concrete Operational Stage In Piaget's theory, the third stage of cognitive development, which lasts from about age 7 to adolescence; characterized by the ability to think logically about concrete objects and situations. Formal Operational Stage In Piaget's theory, the fourth stage of cognitive development, which lasts from adolescence through adulthood; characterized by the ability to think logically about abstract principles and hypothetical situations. Information-Processing Model of Cognitive Development The model that views cognitive development as a process that is continuous over the lifespan and that studies the development of basic mental processes such as attention, memory, and problem solving. Adolescence The transitional stage between late childhood and the beginning of adulthood, during which sexual maturity is reached. Identity A person's definition or description of himself or herself, including the values, beliefs, and ideals that guide the individual's behavior. Moral Reasoning The aspect of cognitive development that has to do with how and individual reasons about moral decisions.