accommodation the altering of previous concepts in response to new information.

acne vulgaris a common, chronic skin disease, especially among adolescents and young adults, characterized by inflammation of the sebaceous apparatus, causing pimples on the face, back, and chest.

acquired immunodeficiency syndrome (AIDS) a condition in which acquired deficiency of certain leukocytes, especially T cells, results in a variety of infections, some forms of cancer, and the degeneration of the system: caused by a virus that infects T cells and is transmitted via body fluids, especially sexual secretions and blood.

active euthanasia the deliberate termination of life to eliminate pain.

activity theory sees a positive correlation between keeping active and aging well.

acuity acuteness; keenness, as of thought or vision.

adaptation a change in behavior to meet situational demands.

adolescence ages 12 to 19.

adolescent growth spurt a noticeable increase in height and weight during adolescence.

adult learners students age 25 or older.

affective disorder a mood disorder that causes a person to experience abnormally high and/or low feelings.

age clock the internal sense of timing of physical and social events that determines the various life stages through which adults pass

ageism discrimination against people on the basis of age; specifically, discrimination against, and prejudicial stereotyping of, older people

age-30 transition a stage in the novice phase of early adulthood; early adulthood ranging from ages 28 to 33.

aggression forceful, attacking behavior, either constructively self-assertive and self-protective or destructively hostile to others or to oneself.

Alzheimer's disease a progressive, irreversible disease characterized by degeneration of the brain cells and commonly leading to severe dementia.

ambidextrous able to use both hands with equal ease.

amniocentesis test the surgical procedure of inserting a hollow needle through the abdominal wall into the uterus of a pregnant woman and extracting amniotic fluid, which may be analyzed to determine the sex of the developing fetus or the presence of disease, genetic defects, and so on.

amnion the innermost membrane of the sac enclosing the embryo; it is filled with a watery fluid called amniotic fluid.

amniotic fluid the watery fluid that fills the amniotic sac and cushions the developing fetus against injury and shock and provides constant temperature in the amniotic sac.

amniotic sac a double-layered membrane formed from the fusion of the amnion and chorion; it encloses the embryo and is filled with amniotic fluid.

anal expulsive refers to traits in an adult - such as messiness and altruism - that may be regarded as unconscious psychic residues of the anal stage.

anal retentive refers to traits in an adult - such as orderliness, stinginess, strict adherence to schedules, and obstinancy - that may be regarded as unconscious psychic residues of the anal stage.

anal stage the second stage of psychosexual development, in which interest centers on excretory functions.

anger one of Elisabeth Kubler-Ross's stages of dying, in which the dying feel resentment or rage about their terminal illness.

anorexia nervosa an eating disorder, chiefly in young women, characterized by aversion to food and obsession with weight loss; manifested in self-induced starvation, excessive exercise, and so on.

anticipatory grief feelings of loss and guilt while the dying person is still alive.

anxiety disorder an abnormal state, characterized by a feeling of being powerless and unable to cope with threatening events, typically imaginary, and by physical tension, as shown by sweating, trembling, and so on.

applied intelligence practical IQ.

asexual not having sexual interests or abilities.

assimilation the application of previous concepts to new concepts.

assisted suicide suicide committed with the assistance of a physician by a person terminally ill or in unmanageable pain.

attachment the bond between a mother and child; also, the process whereby one individual seeks nearness to another individual.

authoritarian parents parents who demonstrate high parental control and low parental warmth when interacting with their children.

authoritative parents parents who demonstrate appropriate levels of both parental control and parental warmth.

autonomy the ability to function independently without control by others.

babble the meaningless sounds babies make while learning to control their vocalizations.

bacteria tiny creatures making up a division (Bacteria) of microorganisms that are typically one-celled, have no chlorophyll, multiply by simple division, and can be seen only with a microscope: They occur in three main forms, spherical (cocci), rod-shaped (bacilli), and spiral (spirilla); some bacteria cause diseases such as pneumonia and anthrax, and others are necessary for fermentation, nitrogen fixation, and so on.

ballottement a type of pelvic examination in which a physician or nurse feels for a fetus in the uterus.

bargaining one of Elisabeth Kubler-Ross's stages of dying in which the dying tries to bargain with God or another religious figure, promising to change, make amends, or atone for his or her wrongdoings in order to avoid death.

basic intelligence academic IQ.

bereavement to be left in a sad or lonely state, as by loss or death.

bibliotherapy dealing with death by reading books about dying.

bilingual using or capable of using two languages, especially with equal or nearly equal facility.

biopsychosocial perspective studies human development by examining the interaction of biological, psychological, and social factors.

bipolar disorder a psychotic disorder characterized by alternating periods of mania and mental depression; manic-depressive illness.

birth trauma injury incurred during birth.

bisexual sexually attracted to both sexes.

blastocyst an embryo at the stage of development in which it consists of usually one layer of cells around a central cavity, forming a hollow sphere.

blended families stepfamilies, in which new family units are made up of children from previous marriages.

borderline personality disorder a mental illness characterized by rapid shifts in the liking and hating of self and others.

breech presentation the delivery of a fetus presenting itself with its buttocks or feet first.

bulimia nervosa an eating disorder, chiefly in young women, characterized by the gorging of large quantities of food followed by purging, as through self-induced vomiting.

burnout a state of mental exhaustion characterized by feelings of helplessness and loss of control, as well as the inability to cope with or complete assigned work.

case study research research in which an investigator studies an individual who has a rare or unusual condition or who has responded favorably to a new treatment.

celibate abstaining from sexual intercourse.

cephalocaudal order the order in which fetal development occurs, beginning with the head and ending with the lower body and extremities.

cerebral hemisphere either of the two lateral halves of the cerebrum.

cesarean section (C-section) a surgical operation for delivering a baby by cutting through the mother‘s abdominal and uterine walls.

child development the maturation of children.

child molestation the sexual abuse of a child, which occurs when a teenager or adult entices or forces a child to participate in sexual activity.

child physical abuse the intentional infliction of pain, injury, and harm onto a child.

chloasma a skin discoloration on the face and chest, resulting from pregnancy, disease, malnutrition, and so on.

chorion the outermost of the two membranes that completely envelop a fetus.

chorionic villi small fingerlike projections in the placenta through which fetal blood circulates.

chorionic villus sampling a test for detecting genetic abnormalities, determining sex, and so on in a fetus: Tissue samples of chorionic villus are removed from the uterus.

chromosomes any of the microscopic rod-shaped bodies formed by the incorporation of the chromatin in a cell nucleus during mitosis and meiosis: They carry the genes that convey hereditary characteristics, and are constant in number for each species.

chronological age actual age.

classical conditioning (Pavlovian) a situation in which learning occurs by association when a stimulus that evokes a certain response becomes associated with a different stimulus that originally did not cause that response.

classification the ability to group according to features.

cognitive appraisal how people perceive and interpret the effects that situations have on them.

cohabitation to live together as husband and wife, especially when not legally married.

colostrum the first fluid, rich in protein, secreted by the mother‘s mammary glands for several days just after birth of the young.

companionate love a relationship in which two people are both committed and intimate, but not passionate.

conception when a sperm and egg unite, resulting in an embryo or fetus.

congenital defects birth defects existing as such at birth.

conservation the concept that physical properties remain constant even as appearance and form changes.

consummate love the ideal form of love in adulthood that involves three components: passion, intimacy, and commitment.

contextual intelligence the ability to apply intelligence practically, including taking into account social, cultural, and historical contexts.

continuing education classes taken by adults to expand their knowledge or skills for personal or work-related development.

continuity versus discontinuity debate examines the question of whether development is solely and evenly continuous, or whether it is marked by age-specific periods.

conventional morality characterized by conformity, helping others, obeying the law, and keeping order.

cooperative learning adult-supervised education that relies on peers' interacting, sharing, planning, and supporting each other.

corpus callosum the bands of neural fibers connecting the two cerebral hemispheres.

corpus luteum during the early stages of pregnancy, a mass of yellow tissue formed in the ovary by a ruptured graafian follicle that has discharged its ovum: If the ovum is fertilized, this tissue secretes the hormone progesterone, needed to maintain pregnancy.

correlation the degree of relative correspondence, as between two sets of data.

cortex the higher areas of the brain, which are responsible for thinking and planning.

co-sleeping children sleeping in the same bed as their parents.

critical periods times of increased and favored sensitivity to particular aspects of development.

cross-cultural research research designed to reveal variations existing across different groups of people.

cross-gender behaviors behaviors stereotypical of the opposite sex.

cross-sectional study a study in which a number of different-age individuals with the same trait or characteristic of interest are studied at a single time.

cross-sequential study a study in which individuals in a cross-sectional sample are tested more than once over a specified period of time.

crowning the point during labor when the baby's head can be seen at the vaginal orifice.

crystallized intelligence the ability to use learned information collected throughout a life span.

culminating phase a phase of early adulthood that ranges from ages 33 to 45.

culture-fair IQ tests tests that are fair for all members in a culture.

culture-free IQ tests tests without cultural content.

death the permanent cessation of all life functions.

death education provides people with information on dying, legal issues, and various practical matters.

debrief to give information concerning research that has just been completed.

deception concealing the purpose and procedures of a study from participants.

deciduous teeth baby teeth; teeth that fall out at a certain stage of growth.

decision/commitment making the decision to commit to a relationship with another person.

delivery expelling the baby and placenta from the vagina.

dementia mental deterioration; a severe organic mental deficiency or impairment.

denial one of Elisabeth Kubler-Ross's stages of dying, in which the dying refuse to acknowledge their inevitable death, perhaps believing a mistake has been made.

dependent variable a variable whose value is determined by the value of another variable.

depression an emotional condition, either neurotic or psychotic, characterized by feelings of hopelessness, inadequacy, and so on; also one of Elisabeth Kubler-Ross's stages of dying.

depth perception the ability to see objects in perspective.

descriptive statistics statistics used for describing the characteristics of the population and subjects.

despair a loss of hope; Erik Erikson believed that those in late adulthood struggled with the fear that there is too little time to begin a new life course.

developmental psychology the scientific study of age-related changes throughout the human life span.

developmentalists researchers who study human development.

developmentally disabled persons who are slowed or delayed in development or progress, especially because of subnormal intellectual functioning and social skills.

diabetes mellitus a chronic form of diabetes involving an insulin deficiency and characterized by an excess of sugar in the blood and urine, and by hunger, thirst, and gradual loss of weight.

dialect the form or variety of a spoken language peculiar to a region, community, social group, occupational group, and so on.

didactic learning an educational method in which a teacher lectures to students.

discipline treatment that corrects or punishes and is intended to control or to establish habits of self-control.

disengagement theory views aging as a process of mutual withdrawal in which older adults voluntarily slow down by retiring, as expected by society.

distance education taking courses through alternative learning formats, such as intensive study classes conducted one weekend per month, telecourses provided over the television, or virtual classrooms set up on the Internet.

distortion when a subject does not respond honestly to questions.

distressor a negative event, such as a death or loss of a job, that is stressful.

divorce the legal and formal dissolution of a marriage.

early adult transition a stage in the novice phase of early adulthood, ranging from ages 17 to 22.

early adulthood ages 17 to 45.

early childhood ages 2 to 6.

early phase of labor the phase of labor that consists of mild, minute-long contractions that occur every 15 minutes.

eclampsia an attack of convulsions; specifically, a disorder that may occur late in pregnancy, characterized by convulsions, edema, and elevated blood pressure.

ectoderm the outer layer of cells of an embryo from which the nervous system, skin, hair, teeth, and so on are developed.

ectopic pregnancy a pregnancy with the fertilized ovum developing outside the uterus, as in a fallopian tube.

ego that part of the psyche that experiences the external world, or reality, through the senses, organizes the thought processes rationally, and governs action; it mediates between the impulses of the id, the demands of the environment, and the standards of the superego.

ego integrity maintaining one's sense of wholeness.

egocentric viewing everything in relation to oneself; self-centered.

elderly abuse the neglect and/or physical and emotional abuse of dependent elderly persons.

Electra complex the unconscious tendency of a daughter to be attached to her father and hostile toward her mother.

embryo an animal in the earliest stages of its development in the uterus or the egg, specifically, in humans, from conception to about the eighth week.

empathy the projection of one's own personality into the personality of another in order to understand the person better; ability to share in another's emotions, thoughts, or feelings.

empty-nest syndrome a form of mental depression said to be caused in parents by the loss felt when their children grow up and leave home.

endoderm the inner layer of cells of the embryo, from which the lining of the digestive tract, other internal organs, and certain glands are formed.

endometrium the inner lining of the uterus.

entering the adult world a stage in the novice phase of early adulthood, ranging from ages 22 to 28.

episiotomy incision of the perineum, often performed during childbirth to prevent injury to the vagina.

equilibrium Piaget's term for the basic process underlying the human ability to adapt; the search for balance between self and the world.

erogenous zone an area of the body that is particularly sensitive to sexual stimulation.

estrogen any of several female sex hormones that cause estrus; estrogen helps to stimulate enlargement of the reproductive organs and relaxation of associated ligaments, stimulate development of the uterine lining and mammary glands, and prevent contractions of the uterus.

ethical dilemma a situation in which a researcher must make a difficult moral decision.

eustressor a positive event, such as marriage or vacations, that is stressful.

euthanasia act or practice of causing death painlessly in order to end suffering: advocated by some as a way to deal with persons dying of incurable, painful diseases.

existential anxiety emotional troubles that arise from the denial of death.

existential psychology the search for meaning in life through the study of death.

experiential intelligence the ability to transfer learning effectively to new skills.

experimental research research based on, tested by, or having the nature of an experiment.

experimenter bias when researchers' expectations about what should or should not happen in a study sway the results.

extramarital affair having sexual intercourse with someone other than one's spouse.

extraneous variable a variable unrelated to an experiment (such as room temperature or noise level) that may interfere with the results of the experiment.

fallopian tube either of two slender tubes that carry ova from the ovaries to the uterus.

family of origin the family one was born into or raised by.

fear a feeling of anxiety and agitation caused by the presence or nearness of danger, evil, pain, and so on.

fetal alcohol syndrome a condition affecting infants, characterized variously by mental retardation, heart defects, physical malformations, and so on and caused by excessive consumption of alcohol by the mother during pregnancy.

fetus the unborn young of an animal while still in the uterus or egg, especially in its later stages and specifically, in humans, from about the eighth week after conception until birth.

fimbria a fringe or border of hairs, fibers, and so on or a fringelike process, especially at the opening of an oviduct in mammals.

fine motor skills the use of small bodily movements, such as drawing or writing.

fixation an exaggerated preoccupation; obsession.

flagellum a whiplike part or process of some cells, especially of certain bacteria, protozoans, and so on, that is an organ of locomotion or produces a current in the surrounding fluid.

fluid intelligence the ability to think abstractly and deal with novel situations.

folkway any way of thinking, feeling, behaving, and so on common to members of the same social group.

formal operations according to Piaget, individuals enter this stage in adolescence as they gain the ability to classify and compare objects and ideas, systematically seek solutions to problems, and consider future possibilities.

fraternal twins two fetuses produced from separate eggs.

friendship a loving relationship characterized by intimacy, but not by passion or commitment.

frontal lobes lobes located in the front of the brain just under the skull, which are responsible for planning, reasoning, social judgment, and ethical decision making, among other functions.

full-term babies babies who arrive on or shortly before or after their due dates.

gay bashing attacks against homosexuals - either verbal or physical.

gender the fact or condition of being a male or a female human being, especially with regard to how this affects or determines a person's self-image, social status, goals, and so on.

gender identity an individual's personal sense of maleness or femaleness.

gender role outward expression of gender identity, according to cultural and social expectations.

gender schemas deeply embedded cognitive frameworks regarding what defines masculine and feminine.

gene any of the units occurring at specific points on the chromosomes, by which hereditary characters are transmitted and determined: Each is regarded as a particular state of organization of the chromatin in the chromosome, consisting primarily of DNA and protein.

generalize to formulate general principles or inferences from particulars.

generativity the desire to expand one's influence and commitment to family, society, and future generations.

genital stage adult or final stage of psychosexual development in which conflicts have been resolved, libidinal drives regulated, and character structure integrated.

gerontologists those who study the process of aging and of the problems of aged people.

gerontology the scientific study of the process of aging and of the problems of aged people.

gestation the act or period of carrying young in the uterus from conception to birth; pregnancy.

glial cells nervous system support cells surrounding neurons.

grief intense emotional suffering caused by loss, disaster, misfortune, and so on; acute sorrow; deep sadness.

grief therapy treatment that helps individuals deal with their grief and bereavement.

gross motor skills the use of large bodily movements, including running, jumping, hopping, turning, skipping, throwing, balancing, and dancing.

handedness ability in using one hand more skillfully than, and in preference to, the other.

hardiness resistance to stress.

heterosexual of or characterized by sexual desire for those of the opposite sex.

holophrase a single word that conveys complete ideas.

homophobia irrational hatred or fear of homosexuals or homosexuality.

homosexual of or characterized by sexual desire for those of the same sex as oneself.

hospice a homelike facility to provide supportive care for terminally ill patients.

human chorionic gonadotropin (HCG) the hormone that is secreted by the placenta early in pregnancy and which inhibits menstrual periods.

hyaluronidase an enzyme that inactivates hyaluronic acid by breaking down its polymeric structure, thus promoting the diffusion of substances through tissues: found in sperm cells, certain venoms and bacteria, and so on.

hypothesis an unproved theory, proposition, supposition, and so on, tentatively accepted to explain certain facts or to provide a basis for further investigation, argument, and so on.

hysterectomy the surgical removal of all or part of the uterus.

id that part of the psyche that is regarded as the reservoir of the instinctual drives and the source of psychic energy; it is dominated by the pleasure principle and irrational wishing, and its impulses are controlled through the development of the ego and superego.

identical triplets three fetuses produced from the same ovum.

identical twins two fetuses produced from the same ovum.

identification a mainly unconscious process by which a person formulates a mental image of another person and then thinks, feels, and acts in a way that resembles this image.

identity the condition or fact of being a specific person or thing; individuality.

identity crisis the condition of being uncertain of one's feelings about oneself, especially with regard to character, goals, and origins, occurring especially in adolescence as a result of growing up under disruptive, fast-changing conditions.

incest sexual activity between closely related persons of any age.

independent variable a variable whose value may be determined freely without reference to other variables.

indifferent parents parents who demonstrate low parental control and low warmth.

industry the feeling of social competence; according to Erikson, the primary developmental task of middle childhood is to attain industry.

infancy birth to age 1.

infant mortality the percentage of babies who die within the first year of life.

infatuation completely carried away by foolish or shallow love or affection.

inferential statistics statistics used for making predictions about the population.

infertile the inability to produce offspring because of some disorder of the reproductive system.

informed consent when a subject agrees to participate in a study based on disclosure of personal information.

initiative the ability to think and act without being urged; enterprise.

injunctions messages received during childhood.

intelligence the ability to learn or understand from experience; ability to acquire and retain knowledge; mental ability.

intelligence quotient (IQ) a number intended to indicate a person's level of intelligence: It is the mental age (as shown by intelligence tests) multiplied by 100 and divided by the chronological age.

interactional theory of homosexuality a theory stating that sexual orientation develops from a complex interaction of biological, psychological, and social factors.

interviewer bias an error in research that occurs when an interviewer's expectations or gestures influence a subject's responses.

intimacy the sense of warmth and closeness in a loving relationship, including the desire to help the partner, self-disclose, and keep him or her in one's life.

juvenile delinquency the breaking of the law by minors.

labor the process or period of childbirth; parturition; especially, the muscular contractions of giving birth.

Lamaze method a training program in natural childbirth, emphasizing breathing control and relaxation during labor together with the presence and encouraging assistance of a partner.

late adulthood those years that encompass age 65 and beyond, according to Daniel Levinson.

late phase of labor the phase of labor in which contractions become very painful and the cervix dilates completely to 10 cm, or 4 inches.

lateralization the localization of assorted functions, competencies, and skills in either or both hemispheres.

learning the acquiring of knowledge or skill.

life review the process of reminiscing and examining the scope of one's life.

living will a document, legal in some states, directing that all measures to support life be ended if the signer should be dying of an incurable condition.

long-term memory a type of memory in which information is stored indefinitely.

longitudinal study a study in which the same individuals are studied repeatedly over a specified period of time.

low birthweight baby a baby born weighing less than 5-1/2 pounds.

lunar month a four-week period of 28 days.

male climacteric male menopause.

marriage to be joined as husband and wife; united in wedlock.

memory the power, act, or process of recalling to mind facts previously learned or past experiences.

menarche the first menstrual period of a girl in puberty.

menopause the permanent cessation of menstruation, normally between the ages of 40 and 50, or the period during which this occurs; female climacteric, or change of life.

menstruate to have a menstrual period; undergo menstruation.

mental age an individual's degree of mental development measured in terms of the chronological age of the average individual of corresponding mental ability.

mesoderm the middle layer of cells of an embryo, from which the skeletal, reproductive, muscular, vascular, and connective tissues develop.

metacognition the awareness of one's own cognitive processes.

metamemory the ability to comprehend the nature of memory and predict how well one will remember something.

midcareer reassessment a reevaluation of one's career at midlife, which may lead to a career change.

middle childhood ages 7 to 11.

middle phase of labor that phase of labor in which contractions increase in strength and frequency, and the cervix dilates to at least 5 cm, or 2 inches.

midlife crisis the sense of uncertainty or anxiety about one's identity, values, relationships, and so on that some people experience in midlife.

midlife transition a change in lifestyle or career that some people may experience at midlife; also, a stage in the culminating phase of early adulthood, ranging from ages 40 to 45.

midwife a person whose work is helping women in childbirth.

miscarriage the natural expulsion of an embryo or fetus from the womb before it is sufficiently developed to survive.

mitochondria any of various very small, usually rodlike, structures found in the cytoplasm of eukaryotic cells and that serve as a center of intracellular enzyme activity that produces the ATP needed to power the cell.

mnemonic devices various devices that help, or are meant to help, the memory.

moral development and judgment the ability to reason about right and wrong.

mores formal rules of acceptable behavior that are considered conducive to the welfare of society and so, through general observance, develop the force of law, often becoming part of the formal legal code.

morning sickness a condition of nausea and vomiting, sometimes accompanied by dizziness, headache, and so on, that affects many women during the first months of pregnancy; it occurs most often in the morning.

motor skills the ability to move with intention.

mourning the actions or feelings of one who feels or expresses sorrow; specifically, the expression of grief at someone‘s death.

multi-infarct dementia dementia resulting from a stroke.

multiple pregnancy a pregnancy in which two or more eggs are fertilized, or a single fertilized egg divides into two or more zygotes.

mutuality synchronous (back-and-forth) interaction between individuals.

myelin sheaths a white, fatty material that surrounds, insulates, and increases the efficiency of neurons.

nature-versus-nurture debate arguments concerning the relative degree to which heredity and learning affect functioning.

neonatal period the first 4 weeks of life outside the womb.

neurons the structural and functional unit of the nervous system, consisting of the nerve cell body and all its processes, including an axon and one or more dendrites.

nocturnal emissions the release of semen during sleep (wet dreams).

nonviable fetus a fetus that is unable to live on its own.

norm a way of behaving typical of a certain group.

novice phase a phase of early adulthood, ranging from ages 17 to 33.

obesity being 20 percent or more above one's ideal weight.

object permanence the knowledge that out-of-sight objects still exist, learned by infants at around 9 months.

object-relations theory Melanie Klein's theory that the inner core of personality stems from the early relationship with the mother.

observational learning the process by which learning is achieved through observing and imitating others.

observational research research based on the observation of subjects in laboratory or natural settings rather than on experimentation or interviews.

Oedipus conflict the unconscious tendency of a child to be attached to the parent of the opposite sex and hostile toward the other parent. Its persistence in adult life results in neurotic disorders. Originally restricted to a son's attachment.

only child a child without siblings.

operant conditioning a form of conditioning in which the desired response, when it occurs, is reinforced by a stimulus.

oral stage the earliest stage of psychosexual development in which interest centers around sucking, feeding, and biting.

organic brain syndrome mental deterioration, also known as dementia.

ovulate to produce and discharge ova from the ovary.

ovum a mature female germ cell which, only after fertilization, develops into a zygote and then a fetus.

paranoia a mental disorder characterized by systematized delusions, as of grandeur or, especially, persecution; often, except in a schizophrenic state, occurring within an otherwise relatively intact personality.

parental control the degree to which parents are restrictive in their use of parenting techniques.

parental warmth the degree to which parents are loving, affectionate, and approving in their use of parenting techniques.

participant observation research that requires an observer to become a member of his or her subjects' community.

parturition the act of bringing forth young; childbirth.

passion intense feelings of physiological arousal and excitement.

passive euthanasia the deliberate withdrawal or withholding of life-sustaining treatment that may otherwise prolong the life of the dying person.

pedophilia an abnormal condition in which an adult has a sexual desire for children.

peer pressure to be forced or compelled to do something by one's peers.

perception the psychological process by which the human brain processes the sensory data collected by the sensory organs.

perineum the region of the body between the thighs, at the outlet of the pelvis; specifically, the small area between the anus and the vulva in the female or between the anus and the scrotum in the male.

permissive parents parents who demonstrate high parental warmth and low parental control when interacting with their children.

personality habitual patterns and qualities of behavior of any individual as expressed by physical and mental activities and attitudes; distinctive individual qualities.

petting sexual activities other than intercourse.

phallic stage designating or of the third stage of psychosexual development in which interest centers around the genital organs.

phenylketonuria (PKU) a genetic disorder of phenylalanine metabolism, which, if untreated, causes severe mental retardation in infants through the accumulation of toxic metabolic products.

physical development the biological changes that humans undergo as they age.

physical disability any physical defect, change, difficulty, or condition that has the potential to disrupt daily living.

physical intimacy mutual affection and sexual activity.

placenta a vascular organ that is connected to the embryo by the umbilical cord and that is discharged shortly after birth; the structure serves to provide nourishment for and eliminate wastes from the fetus.

placental lactogen a hormone produced by the placenta that prepares the mammary glands to secrete milk.

population a body of persons having qualities or characteristics in common.

positive reinforcement the rewarding of acceptable behaviors.

postconventional morality moral reasoning and behavior characterized by accepting the relative and changeable nature of rules and laws, and conscience-directed concern with human rights.

postformal thinking the objective use of practical common sense to deal with unclear problems.

postmature baby an infant who is born 2 or more weeks after its due date.

postpartum stage the period following childbirth.

preadolescence the period of childhood between ages 10 and 11.

preconventional morality moral reasoning and behavior based on rules and fear of punishment and nonempathetic self-interest.

prefrontal cortex the most anterior (front) portion of the frontal lobes; appears to be responsible for personality.

pregnancy the condition, quality, or period of having (an) offspring developing in the uterus.

prejudice suspicion, intolerance, or irrational hatred of other races, creeds, regions, occupations, and so on.

premature (preterm) birth a birth that occurs before a gestation of 37 weeks.

preoperational stage according to Piaget, the stage of cognitive development that occurs between ages 2 and 7.

presbycusis difficulty hearing high-pitched sounds.

presbyopia a form of farsightedness occurring after middle age, caused by a diminished elasticity of the crystalline lens.

primary sex characteristics any of the physical characteristics differentiating male and female individuals; directly responsible for reproduction.

productive language an ability to use the spoken or written word.

progesterone a hormone secreted by the corpus luteum, active in preparing the uterus for the reception and development of the fertilized ovum and the mammary glands for milk secretion.

promiscuity characterized by a lack of discrimination; specifically, engaging in sexual intercourse indiscriminately or with many persons.

prosocial behavior the capacity to help, cooperate, and share with others.

psychiatric disability a mental illness or psychological disturbance, causing a person to struggle with mild to incapacitating emotional problems and limitations that are often caused by either anxiety or affective disorders.

psycholinguists specialists in the study of language.

psychological intimacy the sharing of feelings and thoughts.

psychosexual development Freud's theory that children systematically move through oral, anal, phallic, and latency stages before reaching mature adult sexuality in the genital stage.

psychosocial of or pertaining to the psychological development of the individual in relation to his or her social environment.

puberty the stage of physical development when secondary sex characteristics develop and sexual reproduction first becomes possible: in common law, the age of puberty is generally fixed at fourteen for boys and twelve for girls.

punishment the infliction of some penalty on a wrongdoer.

qualitative research research in which information collected from respondents takes the form of verbal descriptions or direct observations of events.

quantitative research research in which information is collected from respondents and converted into numbers.

questionnaire a written or printed form used in gathering information on some subject or subjects, consisting of a set of questions to be submitted to one or more persons.

quickening the stage of pregnancy in which the movement of the fetus can be felt for the first time.

random sample a sample in which each member of a population has an equal chance of being chosen as a subject.

Raven's Progressive Matrices Test an IQ test that gauges the subject's ability to solve problems that are presented in unfamiliar designs.

receptive language an understanding of the spoken and written word.

reductionistic perspective studies human development by reducing complex phenomenon or events to a single cause.

reflex an involuntary action, as a sneeze, resulting from a stimulus that is carried by an afferent nerve to a nerve center and the response that is reflected along an efferent nerve to some muscle or gland.

refractory periods the waiting time before men can regain an erection after they have ejaculated.

reliable that which can be relied on; dependable; trustworthy; in testing, provides consistent results when administered on different occasions.

representational thought symbolic thought, which children begin exhibiting around ages 18 to 24 months.

Rh factor incompatibility group of antigens, determined by heredity and usually present in human red blood cells, that may cause hemolytic reactions during pregnancy or after transfusion of blood containing this factor into someone lacking it.

rubella a mild, infectious, communicable virus disease, characterized by swollen glands, especially of the back of the head and neck, and small red spots on the skin; German measles.

sample a selected segment of a population studied to gain knowledge of the whole.

schemas Piaget's term for innate thinking processes.

scientific method a systematic approach to researching questions and problems through objective and accurate observation, collection and analysis of data, direct experimentation, and replication of these procedures.

secondary sexual characteristic any of the physical characteristics that differentiate male and female individuals, as distribution of hair or fat on the body, breast and muscle development, deepening of the voice, and so on, that are not directly related to reproduction and usually appear at puberty.

selective attention the ability to focus or concentrate closely on something.

self-concept one's conception of oneself and one's own identity, abilities, worth, and so on.

self-esteem belief in oneself; self-respect.

senile showing the marked deterioration often accompanying old age, especially mental impairment characterized by confusion, memory loss, and so on.

sensation the power or process of receiving conscious sense impressions through direct stimulation of the bodily organism; an immediate reaction to external stimulation of a sense organ; conscious feeling or sense impression.

sensorimotor of or pertaining to motor responses initiated by sensory stimulation.

sensorimotor stage according to Piaget, from birth to age 2, infants and toddlers learn by doing: looking, hearing, touching, grasping, and sucking.

sensory memory a form of memory in which information is retained for less than 1 second.

sensory organs specialized structures of the body containing sensory receptors that receive stimuli from the environment.

sensory receptors convert environmental energy into nervous-system signals that the brain can understand and interpret.

separation anxiety distress at the prospect of being left alone in an unfamiliar place or being separated from a familiar person.

serial ordering the ability to group according to logical progression.

settling down a stage in the culminating phase of early adulthood, ranging from ages 33 to 40.

sex role the quality of being male or female, based on anatomy.

sexual latency inactive sexual interest.

sexual orientation an individual's sexual, emotional, romantic, and affectionate attraction to members of the same sex, the other sex, or both.

short-term memory a form of memory in which information is retained for less than 30 seconds.

size and shape constancy the consistent size and shape of objects.

social cognition experiential knowledge and understanding of society and the rules of social behavior.

social deprivation the absence of attachment.

social inferences assumptions about the nature of social relationships, processes, and others' feelings.

social intimacy having the same friends and enjoying the same types of recreation.

socializing agents those influences that teach and reinforce society's rules and norms.

stable identity the concept that one's self remains consistent even when circumstances change.

stage theories of development theories that suggest that people go through a series of discrete stages, each of which is characterized by at least one task that an individual must accomplish before progressing to the next stage.

stagnation a state of self-absorption, self-indulgence, and invalidism that middle adults may experience if they fail to develop generativity.

Stanford-Binet Intelligence Scale a popular IQ test.

state a set of circumstances or attributes characterizing a person or thing at a given time; way or form of being; condition.

statistics facts or data of a numerical kind, assembled, classified, and tabulated so as to present significant information about a given subject.

stillbirth the birth of a dead fetus after 20 weeks.

stranger anxiety distress in the presence of unfamiliar people.

stress mental or physical tension or strain.

subcortical the lower areas of the brain, which are responsible for basic life functions.

subjects members of a population who participate in a study.

sudden infant death syndrome (SIDS) the sudden death of an apparently healthy infant, of unknown cause but believed to be related to some faulty mechanism in respiration control.

suicide the act of killing oneself intentionally.

superego that part of the psyche that is critical of the self or ego and enforces moral standards: at an unconscious level it blocks unacceptable impulses of the id.

survey research research that involves interviewing or administering questionnaires to large numbers of people.

telegraphic speech speech of 1 to 2-year-olds in which two or more meaningful words are put together to form brief sentences.

teratogen an agent, as a chemical, disease, and so on, that causes malformation of a fetus.

tetrahydrocannabinol (THC) the hallucinatory chemical that is the principal and most active ingredient in marijuana.

thanatologists those who examine all aspects of death, including biological, psychological, and social issues.

thanatology the study of death, especially of the medical, psychological, and social problems associated with dying.

theory an integrated set of statements that explain various phenomena.

theory of mind an awareness and understanding of others' states of mind and accompanying actions.

toddlerhood ages 1 to 2.

trait a distinguishing quality or characteristic, as of personality.

triarchic theory of intelligence a theory stating that intelligence consists of three factors: information-processing skills, context, and experience.

trimester a period or term of three calendar months (13 weeks).

trophoblast a layer of nutritive ectoderm outside the blastoderm, by which the fertilized ovum is attached to the uterine wall and the developing embryo receives its nourishment.

ultrasound examination (sonogram) an examination that involves bouncing high frequency sound waves off the fetus and transforming the bounced waves into visual images.

umbilical cord a tough, cordlike structure connecting the navel of a fetus to the placenta and serving to supply nourishment to, and remove waste from, the fetus.

unemployment the state of being unemployed; lack of employment.

unipolar depression a mood disorder marked by feelings of self-blame, sadness, guilt, and apathy.

uterus a hollow, muscular organ of female mammals in which the ovum is deposited and the embryo and fetus are developed; womb.

valid well-grounded on principles or evidence; able to withstand criticism or objection, as an argument; sound; in testing, describes a test that measures what it purports to measure.

variable anything changeable; especially, a quality or quantity that varies or may vary.

viable fetus a fetus that is able to live outside of the uterus.

villi any of numerous hairlike or fingerlike vascular processes on certain mucous membranes of the body, as of the small intestine, serving to secrete mucus, absorb fats, and so on; or of the chorion in the mammalian placenta, serving in the exchange of food materials, and so on between the mother and the fetus.

viruses noncellular, microscopic particles that replicate themselves within invaded cells.

volunteer bias an error in research that occurs when a sample of volunteers is not representative of the general population.

Wechsler Intelligence Scale for Children (WISC) a popular IQ test.

widow a woman who has outlived the man to whom she was married at the time of his death; especially, such a woman who has not remarried.

widower a man who has outlived the woman to whom he was married at the time of her death; especially, such a man who has not remarried.

widowhood the disruption of marriage due to the death of the spouse.

wisdom expert and practical knowledge based on life experience.

workaholism addiction to work.

zona pellucida the gelatinous covering of the egg.