false positive The result of a laboratory test that reports something as true when in fact it is not true. This can occur for pregnancy tests, when a woman might not be pregnant even though the test says she is, or during pregnancy when a problem is reported that actually does not exist.

familism The belief that family members should support one another, sacrificing individual freedom and success, if necessary, in order to preserve family unity and protect the family from outside sources.

family function The way a family works to meet the needs of its members. Children need families to provide basic material necessities, to encourage learning, to help them develop self-respect, to nurture friendships, and to foster harmony and stability.

family structure The legal and genetic relationships among relatives living in the same home; includes nuclear family, extended family, stepfamily, and so on.

fast-mapping The speedy and sometimes imprecise way in which children learn new words by tentatively placing them in mental categories according to their perceived meaning.

fetal alcohol syndrome (FAS) A cluster of birth defects, including abnormal facial characteristics, slow physical growth, and reduced intellectual ability, that may occur in the fetus of a woman who drinks alcohol while pregnant.

fetal period The stage of prenatal development from the ninth week after conception until birth, during which the fetus gains about 7 pounds (more than 3,000 grams) and organs become more mature, gradually able to function on their own.

fetus The name for a developing human organism from the start of the ninth week after conception until birth.

fictive kin Someone who becomes accepted as part of a family to which he or she has no blood relation.

filial responsibility The obligation of adult children to care for their aging parents.

fine motor skills Physical abilities involving small body movements, especially of the hands and fingers, such as drawing and picking up a coin. (The word fine here means “small.”)

fluid intelligence Those types of basic intelligence that make learning of all sorts quick and thorough. Abilities such as short-term memory, abstract thought, and speed of thinking are all usually considered part of fluid intelligence.

Flynn effect The rise in average IQ scores that has occurred over the decades in many nations.

fMRI Functional magnetic resonance imaging, a measuring technique in which the brain’s electrical excitement indicates activation anywhere in the brain; fMRI helps researchers locate neurological responses to stimuli.

focus on appearance A characteristic of preoperational thought in which a young child ignores all attributes that are not apparent.

foreclosure Erikson’s term for premature identity formation, which occurs when an adolescent adopts parents’ or society’s roles and values wholesale, without questioning or analysis.

formal operational thought In Piaget’s theory, the fourth and final stage of cognitive development, characterized by more systematic logical thinking and by the ability to understand and systematically manipulate abstract concepts.

foster care A legal, publicly supported system in which a maltreated child is removed from the parents’ custody and entrusted to another adult or family, which is reimbursed for expenses incurred in meeting the child’s needs.

fragile X syndrome A genetic disorder in which part of the X chromosome seems to be attached to the rest of it by a very thin string of molecules. The cause is a single gene that has more than 200 repetitions of one triplet.

frail elderly People over age 65, and often over age 85, who are physically infirm, very ill, or cognitively disabled.

frontal lobe disorder Deterioration of the amygdala and frontal lobes that may be the cause of 15 percent of all dementias. (Also called frontotemporal lobar degeneration and, in the DSM-5, frontotemporal NCD.)