1. Infancy — Sleep & Communication (11 cards)

Six infant sleep/waking states

Deep (quiet) sleep; Active (REM) sleep; Drowsiness; Quiet alert; Active alert; Crying. Newborns cycle through these in ~50-minute cycles.

Why do newborns have so much REM sleep?

REM provides endogenous (internal) stimulation for rapid brain development — called the autostimulation theory (Roffwarg et al.). It substitutes for waking experience and supports neural maturation. Newborns spend ~50% of sleep in REM vs. ~20% for adults.

What is the quiet alert state?

One of the six infant states; eyes are open and attentive, movement is minimal. Considered the optimal state for learning and social interaction.

Evolutionary advantage of infant communication behaviors

Crying, smiling, gaze, and vocalizations keep caregivers close (proximity maintenance) — essential for a highly dependent species. They activate the caregiving behavioral system in adults (Bowlby).

Social smile

Emerges at ~6–8 weeks; infant smiles in response to a human face. Reinforces caregiver engagement and bonding — a key social communication behavior.

Social referencing

Infant looks to caregiver's emotional expression to guide behavior in ambiguous situations (e.g., the visual cliff). Emerges at ~9 months alongside joint attention.

Primary intersubjectivity

Infant's early (0–2 months) direct face-to-face emotional communication with caregiver — mutual gaze and emotional coordination.

Secondary intersubjectivity / joint attention

Emerges ~9 months. Infant and caregiver share attention to a third object or event. Foundation for language learning and social referencing.

Habituation (infant cognition)

Decrease in response to a repeatedly presented stimulus. Infants who habituate to one stimulus and look longer at a novel one demonstrate discrimination and memory.

Violation-of-expectation paradigm

Method used by Baillargeon: infants look longer at physically impossible events (violations). Reveals implicit knowledge of object permanence earlier than Piaget's methods showed.

Rouge test (self-recognition)

Child is marked with rouge on nose without awareness and placed in front of mirror. If child touches own nose, demonstrates self-recognition. Typically emerges 18–24 months.