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 an embryo.
Embryo
The developing human organism, from about 2 weeks after fertilization through the second month.
Fetus
The developing human organism from 9 weeks after conception to birth.
Teratogens
Agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm.
Habituation
Decreasing responsiveness with repeated stimulation.
Maturation
Biological growth processes that enable orderly changes in behavior, relatively uninfluenced by experience.
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 to incorporate new information.
Sensorimotor stage
In Piaget’s theory, the stage 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 during which a child learns to use language but does not yet comprehend the mental operations of concrete logic.
Conservation
The principle 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 ideas about their own and others’ mental states — about their feelings, perceptions, and thoughts, and the behaviors these might predict.
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 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 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.