Temperament
- Concept
Temperament is a baby's inborn style of reacting: how active, regular, adaptable and intense it is. It shapes, but does not fix, later personality.
What it is
Temperament is the set of early, biologically based differences in how a child reacts to stimuli and regulates that reaction. In the New York Longitudinal Study, Thomas and Chess rated infants on nine dimensions and described three broad types: easy, difficult and slow to warm up. Temperament is partly heritable and fairly stable, but the environment and the fit between the child and the caregivers change how it is expressed.
Key facts
- The nine dimensions: activity, rhythmicity, approach or withdrawal, adaptability, intensity, mood, persistence and attention span, distractibility, and sensory threshold.
- Twin studies show moderate heritability (about 20 to 50 %) of many traits, with genes acting together and with the environment.
- Temperament is the early core around which personality later develops.
Thomas and Chess temperament types
| Type | Description | What helps |
|---|---|---|
| Easy (about 40 %) | Regular rhythms, positive mood, adapts quickly to change | Ordinary routines |
| Difficult (about 10 %) | Irregular rhythms, intense and often negative reactions, slow to adapt | Patience, predictable routines, calm consistent limits |
| Slow to warm up (about 15 %) | Mildly negative first reaction to new things, adapts slowly with repeated exposure | Gradual introductions and time, without pressure |
| Mixed (about 35 %) | Does not fit one pattern | Respond to the child's specific traits |
Clinical notes
- Explaining a baby's temperament to parents reduces guilt and helps them adjust routines and expectations.
- Children with high behavioral inhibition are at higher risk of anxiety disorders; supportive, gradual exposure helps more than overprotection.
- In hospital, slow-to-warm-up children need more time before examination and procedures.
Test yourself
Think of the answer, then tap the question to see it.
What are the three temperament types described by Thomas and Chess?
Easy, difficult and slow to warm up.
What does goodness of fit mean?
That outcomes depend on how well the child's temperament matches the expectations and responses of the caregivers and setting.
Which temperamental trait is linked to later anxiety disorders?
Behavioral inhibition: shy, withdrawn reactions to new people and situations.
Connections
Educational content on behavior and the clinical relationship; not a diagnostic or treatment guide and no substitute for assessment by a health professional. If you or someone near you is at risk, seek help now from an emergency service or a mental-health helpline.
Sources: Temperament and Its Role in Developmental Psychopathology (Harvard Review of Psychiatry (PubMed Central), 2005); Not all babies are the same: an examination of temperament profiles during infancy (Frontiers in Psychology (PubMed Central), 2026).
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Representative model, for educational purposes only.