identification An attempt to defend one’s self-concept by taking on the behaviors and attitudes of someone else.

identity achievement Erikson’s term for the attainment of identity, or the point at which a person understands who he or she is as a unique individual, in accord with past experiences and future plans.

identity versus role confusion Erikson’s term for the fifth stage of development, in which the person tries to figure out “Who am I?” but is confused as to which of many possible roles to adopt.

imaginary audience The other people who, in an adolescent’s egocentric belief, are watching and taking note of his or her appearance, ideas, and behavior. This belief makes many teenagers very self-conscious.

imaginary friends Make-believe friends who exist only in a child’s imagination; increasingly common from ages 3 through 7, they combat loneliness and aid emotional regulation.

immersion A strategy in which instruction in all school subjects occurs in the second (usually the majority) language that a child is learning.

immunization A process that stimulates the body’s immune system by causing production of antibodies to defend against attack by a particular contagious disease. Creation of antibodies may be accomplished either naturally (by having the disease), by injection, by drops that are swallowed, or by a nasal spray. (These imposed methods are also called vaccination.)

implantation The process, beginning about 10 days after conception, in which the developing organism burrows into the placenta that lines the uterus, where it can be nourished and protected as it continues to develop.

implicit memory Unconscious or automatic memory that is usually stored via habits, emotional responses, routine procedures, and various sensations.

impulse control The ability to postpone or deny the immediate response to an idea or behavior.

in vitro fertilization (IVF) Fertilization that takes place outside a woman’s body (as in a glass laboratory dish). The procedure involves mixing sperm with ova that have been surgically removed from the woman’s ovary. If a zygote is produced, it is inserted into a woman’s uterus, where it may implant and develop into a baby.

incomplete grief A situation in which circumstances, such as a police investigation or an autopsy, interfere with the process of grieving.

incremental theory of intelligence An approach to understanding intelligence that holds that intelligence can be directly increased by effort; those who subscribe to this view believe they can master whatever they seek to learn if they pay attention, participate in class, study, complete their homework, and so on.

independent variable In an experiment, the variable that is introduced to see what effect it has on the dependent variable. (Also called experimental variable.)

individual education plan (IEP) A document that specifies educational goals and plans for a child with special needs.

inductive reasoning Reasoning from one or more specific experiences or facts to reach (induce) a general conclusion. (Also called bottom-up reasoning.)

industry versus inferiority The fourth of Erikson’s eight psychosocial crises, during which children attempt to master many skills, developing a sense of themselves as either industrious or inferior, competent or incompetent.

infertility The inability to conceive a child after trying for at least a year.

information-processing theory A perspective that compares human thinking processes, by analogy, to computer analysis of data, including sensory input, connections, stored memories, and output.

initiative versus guilt Erikson’s third psychosocial crisis, in which children undertake new skills and activities and feel guilty when they do not succeed at them.

injury control/harm reduction Practices that are aimed at anticipating, controlling, and preventing dangerous activities; these practices reflect the beliefs that accidents are not random and that injuries can be made less harmful if proper controls are in place.

insecure-avoidant attachment 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 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.

instrumental activities of daily life (IADLs) Actions (for example, paying bills and driving a car) that are important to independent living and that require some intellectual competence and forethought. The ability to perform these tasks may be even more critical to self-sufficiency than ADL ability.

instrumental aggression Behavior that hurts someone else because the aggressor wants to get or keep a possession or a privilege.

integrity versus despair The final stage of Erik Erikson’s developmental sequence, in which older adults seek to integrate their unique experiences with their vision of community.

internalizing problems Difficulty with emotional regulation that involves turning one’s emotional distress inward, as by feeling excessively guilty, ashamed, or worthless.

intimacy versus isolation The sixth of Erikson’s eight stages of development. Adults seek someone with whom to share their lives in an enduring and self-sacrificing commitment. Without such commitment, they risk profound aloneness and isolation.

intimate terrorism A violent and demeaning form of abuse in a romantic relationship, in which the victim (usually female) is frightened to fight back, seek help, or withdraw. In this case, the victim is in danger of physical as well as psychological harm.

intra-cytoplasmic sperm injection (ICSI) An in vitro fertilization technique in which a single sperm cell is injected directly into an ovum.

intrinsic motivation A drive, or reason to pursue a goal, that comes from inside a person, such as the need to feel smart or competent.

intrinsic rewards of work The intangible gratifications (e.g., job satisfaction, self-esteem, pride) that come from within oneself as a result of doing a job.

intuitive thought Thought that arises from an emotion or a hunch, beyond rational explanation, and is influenced by past experiences and cultural assumptions.

invincibility fable An adolescent’s egocentric conviction that he or she cannot be overcome or even harmed by anything that might defeat a normal mortal, such as unprotected sex, drug abuse, or high-speed driving.

IQ test A test designed to measure intellectual aptitude, or ability to learn in school. Originally, intelligence was defined as mental age divided by chronological age, times 100—hence the term intelligence quotient, or IQ.

irreversibility A characteristic of preoperational thought in which a young child thinks that nothing can be undone. A thing cannot be restored to the way it was before a change occurred.