Babies feel a range of basic emotions from the very start of life, and their emotional world expands dramatically over the first two years. Newborns arrive with the capacity for distress, contentment, and interest. By the time they reach their second birthday, they’re experiencing emotions as complex as pride, shame, and embarrassment. The timeline in between follows a surprisingly predictable pattern.
What Newborns Actually Feel
In the first weeks of life, a baby’s emotional toolkit is simple but functional. Newborns express distress (through crying), a general state of contentment (when fed, warm, and held), and interest (turning toward voices or faces). These aren’t subtle. A hungry newborn’s cry is unmistakable, and a calm, alert baby gazing at a caregiver’s face is clearly engaged.
What newborns don’t yet have are socially directed emotions. That adorable smile you see in the first few weeks? It’s a reflex, not a response to you. Reflex smiles are short, random, and often happen during sleep or while passing gas. They start before birth and continue through the newborn period. The giveaway is that a reflex smile barely moves the rest of the face, while a genuine social smile lights up the whole expression.
The First Six Months: Joy, Sadness, and Anger Arrive
Around 6 to 8 weeks, babies cross a major emotional milestone: the social smile. This is the first time your baby smiles in direct response to something external, like hearing your voice or seeing your face. Social smiling is considered the earliest true social communication skill, and from 2 to 6 months, babies smile primarily in response to their caregivers. Reflex smiling typically stops right around this same time, as if one system hands off to the other.
By 4 months, babies smile spontaneously, not just as a reaction to someone else smiling first. By 6 months, they produce full, sustained laughter. Around this same period, babies begin showing clearer signs of anger and sadness as distinct states rather than generalized distress. A 5-month-old whose toy is taken away looks different from one who is hungry. The facial expressions become more specific, more recognizable as the emotions adults would label.
Six to Twelve Months: Fear and Surprise Emerge
By 9 months, babies display a noticeably wider emotional range. They make distinct facial expressions for happiness, sadness, surprise, and fear. Stranger anxiety is one of the most visible new emotions during this period. A baby who happily went to anyone at 4 months may now cling to a parent and cry when an unfamiliar person approaches. This isn’t a regression. It reflects a more sophisticated understanding of the world: the baby now recognizes who is familiar and feels genuinely uneasy about who isn’t.
This period also brings the beginnings of social referencing, a behavior where babies look to a caregiver’s face to figure out how to feel about an unfamiliar situation. If a new toy makes a strange noise, a 10-month-old will glance at a parent. A calm, smiling parent signals safety. A worried expression signals danger. By 18 months, this skill is well developed, and toddlers actively seek out emotional cues from the adults around them, sometimes even looking toward strangers during frightening situations to gather more information.
Emotional Contagion: Feeling What Others Feel
One of the more fascinating emotional capacities in the first year is contagious crying. When one baby in a nursery starts to wail, others often join in. For a long time, researchers debated whether this was simply a reaction to a loud, unpleasant noise or something more meaningful. A 2025 cross-cultural study using thermal imaging found evidence that it’s genuinely emotional. Babies within the first year of life experience emotional contagion in response to another infant’s distress, and this effect isn’t just explained by the acoustic unpleasantness of crying.
This sensitivity to others’ emotions is considered a core building block for empathy. It’s not empathy itself, since true empathy requires understanding that someone else is a separate person with their own feelings. But it’s the raw material from which empathy will later develop.
After Age One: Self-Conscious Emotions
The most complex emotions don’t appear until the second year of life, and they require something babies simply don’t have earlier: self-awareness. To feel embarrassment, pride, shame, or guilt, a child must first understand themselves as a separate entity that others can observe and evaluate.
This reflective self-awareness typically emerges in the second half of the second year. By 24 to 26 months, nearly all typically developing children can recognize themselves in a mirror, refer to themselves by name, and display self-conscious emotions. A toddler who beams after stacking blocks successfully is showing pride. One who hides their face after knocking over a sibling’s tower is showing something like shame or embarrassment. These emotions are qualitatively different from the joy or distress of infancy because they involve the child evaluating their own behavior.
How Researchers Know What Babies Feel
Since babies can’t describe their inner experience, scientists rely on multiple types of evidence. Facial expressions are the most obvious, and researchers have developed detailed coding systems that track specific muscle movements around the eyes, mouth, and brow to distinguish between emotional states.
But faces can be misleading, so researchers also measure what’s happening inside the body. Heart rate variability, which reflects how the nervous system regulates arousal, is one of the most reliable physiological markers of emotional stress in infants. At 6 months, babies already show measurable differences in how their autonomic nervous system responds to stressful situations. Cortisol, the body’s primary stress hormone, provides another window. Together, these measures confirm that babies aren’t just making faces. Their bodies are mounting full emotional responses.
Why Early Emotional Environments Matter
A baby’s brain is wiring its emotional circuitry in real time, and the environment shapes that wiring. The brain’s threat-detection center develops early and is ready to respond to stressors from infancy. The prefrontal regions that help regulate those responses, calming fear and managing impulses, are immature during childhood and don’t reach adult-like connectivity until adolescence.
This mismatch means babies and young children feel strong emotions but have very limited ability to manage them on their own. That’s where caregivers come in. Responsive caregiving essentially serves as an external regulator, helping the baby’s nervous system calm down after distress. Research on children who experienced early caregiving disruption found that their brain connectivity between emotional and regulatory regions matured earlier than expected, likely as an adaptation to stress. This accelerated development was linked to higher cortisol levels and greater anxiety, suggesting the brain was compensating for a missing external regulator rather than developing optimally.
The practical takeaway: when you comfort a crying baby, you’re not just stopping the noise. You’re helping build the neural architecture that will eventually let that child manage their own emotions.