developmental psychology
a branch of psychology that studies physical, cognitive, and social change throughout the life span.
zygote
the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo.
embryo
the developing human organism from 2 weeks after fertilization through the second month.
fetus
the developing human organism from 9 weeks after conception to birth.
teratogens
(literally, "monster makers") agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm.
fetal alcohol syndrome (FAS)
physical and cognitive abnormalities in children caused by a pregnant woman's heavy drinking. In severe cases, signs include a small, out-of-porportion head and abnormal facial features.
habituation
decreasing responsiveness with repeated stimulation. As infants gain familiarity with repeated exposure to a visual stimulus, their interest wanes and they look away sooner.
maturation
biological growth processes that enable orderly changes in behavior, relatively uninfluenced by experience.
cognition
all the mental activities associated with thinking, knowing, remembering, and communicating.
schema
a concept or framework that organizes and interprets information.
assimilation
interpreting our new experiences in terms of our existing schemas.
accommodation
adapting our current understandings (schemas) to incorporate new information.
sensorimotor stage
in Piaget's theory, the stage (from birth to about 2 years of age) during which infants know the world mostly in terms of their sensory impressions and motor activities.
object permanence
the awareness that things continue to exist even when not perceived.
preoperational stage
in Piaget's theory, the stage (from 2 to about 6 or 7 years of age) during which a child learns to use language but does not yet comprehend the mental operations of concrete logic.
conservation
the principle (which Piaget believed to be a part of concrete operational reasoning) that properties such as mass, volume, and number remain the same despite changes in the forms of objects.
egocentrism
in Piaget's theory, the preoperational child's difficulty taking another's point of view.
theory of mind
people's idea about their own and others' mental states - about their feelings, perceptions, and thoughts, and the behaviors these might predict.
autism spectrum disorder (ASD)
a disorder that appears in childhood and is marked by significant deficiencies in communication and social interaction, and by rigidly fixated interests and repetitive behaviors.
concrete operational stage
in Piaget's theory, the stage of cognitive development (from about 7 to 11 years of age) during which children gain the mental operations that enable them to think logically about concrete events.
formal operational stage
in Piaget's theory, the stage of cognitive development (normally beginning about age 12) during which people begin to think logically about abstract concepts.
stranger anxiety
the fear of strangers that infants commonly display, beginning by about 8 months of age.
attachment
an emotional tie with another person; shown in young children by their seeking closeness to the caregiver and showing distress on separation.
critical period
an optimal period early in the life of an organism when exposure to certain stimuli or experiences produces normal development.
imprinting
the process by which certain animals form strong attachments during early life.
temperament
a person's characteristic emotional reactivity and intensity.
basic trust
according to Erik Erikson, a sense that the world is predictable and trustworthy; said to be formed during infancy by appropriate experiences with responsive caregivers.
self-concept
all our thoughts and feelings about ourselves, in answer to the question, "Who am I?"
gender
in psychology, the socially influenced characteristics by which people define boy, girl, man, and woman.
aggression
any physical or verbal behavior intended to harm someone physically or emotionally.
gender role
a set of expected behaviors, attitudes, and traits for males or for females.
role
a set of expectations (norms) about a social position, defining how those in the position ought to behave.
gender identity
our sense of being male, female, or some combination of the two.
social learning theory
the theory that we learn social behavior by observing and imitating and by being rewarded or punished.
gender typing
the acquisition of a traditional masculine or feminine role.
transgender
an umbrella term describing people whose gender identity or expression differs from that associated with their birth-designated sex.
adolescence
the transition period from childhood to adulthood, extending from puberty to independence.
identity
our sense of self; according to Erikson, the adolescent's task is to solidify a sense of self by testing and integrating various roles.
social identity
the "we" aspect of our self-concept; the part of our answer to "Who am I?" that comes from our group memberships.
intimacy
in Erikson's theory, the ability to form close, loving relationships; a primary developmental task in late adolescence and early adulthood.
emerging adulthood
a period from about age 18 to the mid-twenties, when many in Western cultures are no longer adolescents but have not yet achieved full independence as adults.
X chromosome
the sex chromosome found in both men and women. Females have two X chromosomes; males have one. An X chromosome from each parent produces a female child.
Y chromosome
the sex chromosome typically found only in males. When paired with an X chromosome from the mother, it produces a male child.
testosterone
the most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs during the fetal period, and the development of the male sex characteristics during puberty.
puberty
the period of sexual maturation, during which a person becomes capable of reproducing.
primary sex characteristics
the body structures (ovaries, testes, and external genitalia) that make sexual reproduction possible.
secondary sex characteristics
nonreproductive sexual characteristics, such as female breasts and hips, male voice quality, and body hair.
menarche
the first menstrual period.
AIDS (acquired immune deficiency syndrome)
a life-threatening, sexually transmitted infection caused by the human immunodeficiency virus (HIV). AIDS depletes the immune system, leaving the person vulnerable to infections.
sexual orientation
an enduring sexual attraction toward members of either one's own sex (homosexual orientation), the other sex (heterosexual orientation), or both sexes (bisexual orientation).
menopause
the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines.
cross-sectional study
research that compares people of different ages at the same point in time.
longitudinal study
research that follows and retests the same people over time.
social clock
the culturally preferred timing of social events such as marriage, parenthood, and retirement.
scaffold
a framework that offers children temporary support as they develop higher levels of thinking.
insecure attachment
demonstrated by infants who display either a clinging, anxious attachment or an avoidant attachment that resists closeness.
secure attachment
demonstrated by infants who comfortably explore environments in the presence of their caregiver, show only temporary distress when the caregiver leaves, and find comfort in the caregiver's return.
strange situation
a procedure for studying child-caregiver attachment; a child is placed in an unfamiliar environment while their caregiver leaves and then returns, and the child's reactions are observed.
androgyny
displaying both traditional masculine and feminine psychological characteristics.
relational aggression
an act of aggression (physical or verbal) intended to harm a person's relationship or social standing.
sex
in psychology, the biologically influenced characteristics by which people define male and female.
intersex
a condition present at birth due to unusual combinations of male and female chromosomes, hormones, and anatomy; possessing biological sexual characteristics of both sexes.
spermarche
the first ejaculation.
Alzheimer's disease
a neurocognitive disorder marked by neural plaques, often with onset after age 80, and entailing a progressive decline in memory and other cognitive abilities.
neurocognitive disorders (NCDs)
acquired (not lifelong) disorders marked by cognitive deficits; often related to Alzheimer's disease, brain injury or disease, or substance abuse.