teratogens
agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm.
rooting reflex
an automatic, unlearned response of a newborn to a gentle stimulus (e.g., the touch of a finger) applied to the corner of the mouth or to the cheek, in which the infant turns their head and makes sucking motions
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.
menarche
the first menstrual period
spermarche
the first ejaculation
menopause
the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines.
sensorimotor stage
in Piaget’s theory, the stage (from birth to nearly 2 years of age) at 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 about 2 to 6 or 7 years of age) at 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.
animism
a belief that inanimate objects are alive or have lifelike feelings and motivations
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
concrete operational stage
in Piaget’s theory, the stage of cognitive development (from about 7 to 11 years of age) at which children can perform the mental operations that enable them to think logically about concrete (actual, physical) events.
formal operational stage
in Piaget’s theory, the stage of cognitive development (normally beginning about age 12) at which people begin to think logically about abstract concepts.
zone of proximal development
the zone between what a child can and can’t do — it’s what a child can do with help
phoneme
in a language, the smallest distinctive sound unit
morpheme
in a language, the smallest unit that carries meaning; may be a word or a part of a word (such as a prefix).
grammar
in a language, a system of rules that enables us to communicate with and understand others. Semantics is the language’s set of rules for deriving meaning from sounds, and syntax is its set of rules for combining words into grammatically sensible sentences.
overgeneralization
the process of extending something beyond the circumstances to which it actually applies. It is a common linguistic tendency of young children to generalize standard grammatical rules to apply to irregular words (e.g., pluralizing foot to foots)
ecological systems theory
a theory of the social environment’s influence on human development, using five nested systems (microsystem; mesosystem; exosystem; macrosystem; chronosystem) ranging from direct to indirect influences.
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.
insecure attachment
demonstrated by infants who display either a clinging, anxious attachment or an avoidant attachment that resists closeness.
separation anxiety
the normal apprehension experienced by a young child when away (or facing the prospect of being away) from the person or people to whom they are attached (particularly parents).
contact comfort
the positive effects experienced by infants or young animals when in close contact with soft materials.
imaginary audience
the belief of an adolescent that others are constantly focusing attention on them, scrutinizing behaviors, appearance, and the like
personal fable
a belief in one’s uniqueness and invulnerability, which is an expression of adolescent egocentrism and may extend further into the lifespan
social clock
the culturally preferred timing of social events such as marriage, parenthood, and retirement