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.

Harmful agents or substances that can cause malformations or defects in an embryo or fetus.

The single cell formed at conception from the union of the egg cell and sperm cell.

The ability to use words, images, and symbols to represent the world.

The third and longest period of prenatal development, extending from the ninth week until birth.

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.

Chromosomes, designated as X or Y, that determine biological sex; the 23rd pair of chromosomes in humans.

The theory that gender-role development is influenced by the formation of schemas, or mental representations, of masculinity and femininity.

The words that are understood by an infant or child.

The genetic makeup of an individual organism.

Condition in which a person’s psychological gender identity conflicts with his or her biological sex.

In Vygotsky’s theory of cognitive development, the difference between what children can accomplish on their own and what they can accomplish with the help of others who are more competent.

The double-stranded molecule that encodes genetic instructions; the chemical basis of heredity.

The first two weeks of prenatal development.

In Piaget’s theory, the inability to take another person’s perspective or point of view.

The words that an infant or child understands and can speak.

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.

The branch of psychology that studies how people change over the lifespan.

The second period of prenatal development, extending from the third week through the eighth week.

Undifferentiated cells that can divide and give rise to cells that can develop into any one of the body’s different cell types.

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.

Inborn predispositions to consistently behave and react in a certain way.

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.

The behaviors, attitudes, and personality traits that are designated as either masculine or feminine in a given culture.

The cultural, social, and psychological meanings that are associated with masculinity or femininity.

A long, thread-like structure composed of twisted parallel strands of DNA; found in the cell nucleus.

The stage of development before birth; divided into the germinal, embryonic, and fetal periods.

A unit of DNA on a chromosome that encodes instructions for making a particular protein molecule; the basic unit of heredity.

In Piaget’s theory, the second stage of cognitive development, which lasts from about age 2 to age 7; characterized by increasing use of symbols and prelogical thought processes.

The study of the cellular mechanisms that control gene expression and of the ways that gene expression impacts health and behavior.

The theory that gender roles are acquired through the basic processes of learning, including reinforcement, punishment, and modeling.

The observable traits or characteristics of an organism as determined by the interaction of genetics and environmental factors.

Research strategy in which individuals of different ages or developmental stages are directly compared.

The understanding that an object continues to exist even when it can no longer be seen.

The emotional bond that forms between an infant and caregiver(s), especially his or her parents.

Research strategy in which a variable or group of variables are studied in the same group of participants over time.

In Piaget’s theory, the inability to mentally reverse a sequence of events or logical operations.

A person’s psychological sense of being male or female.