Temperament and personality are related but distinct constructs, and conflating them causes a lot of confusion in psychological assessment, education, and everyday self-understanding. Temperament refers to the biologically-grounded, early-appearing emotional and behavioural tendencies that show up in infancy and remain relatively stable across the lifespan. Personality is broader — it includes temperament but adds the layer of accumulated experience, learned patterns, values, and identity that develops through life. The distinction matters because it tells you which parts of yourself are most deeply wired and which parts are more open to change.
Where the Distinction Comes From
The separation between temperament and personality became a serious scientific concern in the 1950s and 1960s, when developmental psychologists Alexander Thomas and Stella Chess conducted the New York Longitudinal Study — one of the first systematic attempts to track individual differences in infants from birth into adulthood.
Thomas and Chess identified nine dimensions of infant temperament: activity level, rhythmicity (regularity of biological cycles), approach-withdrawal, adaptability, threshold of responsiveness, intensity of reaction, quality of mood, distractibility, and attention span. These patterns were observable in the first weeks of life, showed meaningful individual differences, and remained reasonably consistent over time.
The key finding: children didn't enter the world as blank slates. They came with characteristic ways of responding to the world that influenced how they were raised and how they developed. But those early tendencies were also shaped by environment — the famous person-environment fit model that emerged from this work held that outcomes depended not just on temperament but on how well the environment matched the child's dispositional profile.
What Temperament Includes
Modern temperament research has converged on a smaller set of core dimensions than Thomas and Chess's original nine. The most widely used frameworks identify three to five dimensions:
- Negative emotionality / Neuroticism — the ease with which the nervous system activates in response to threat or frustration. High scorers experience emotions more intensely and recover more slowly.
- Surgency / Extraversion — approach motivation, the tendency to move toward positive stimulation, novelty, and social engagement. Identifiable in infancy as activity level and positive affect.
- Effortful control — the capacity to regulate attention and behaviour, to inhibit dominant responses when the situation calls for it. This is the temperament dimension most directly connected to executive function and self-regulation.
These dimensions have been identified cross-culturally, show heritability estimates in the 40–60% range in twin studies, and are measurable before language develops.
What Personality Adds
Personality, in the sense used by the Big Five model and most adult assessment frameworks, builds on temperament but includes substantially more. The Big Five dimensions — Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism — overlap with temperament dimensions (Neuroticism and Extraversion in particular map closely) but also reflect learned patterns, values, and self-concept that develop through experience.
Conscientiousness, for example, has a temperament substrate in effortful control — but the adult construct also includes values about work, identity as a responsible person, and patterns formed through decades of reinforcement and choice. Agreeableness similarly reflects early social tendencies but is heavily shaped by attachment history, cultural norms around cooperation, and the lessons drawn from specific relationships.
The simplest formulation: temperament is what you start with; personality is what you become given what you started with and what happened to you.
Stability Over Time
One important practical implication of the temperament-personality distinction concerns what's stable and what's changeable. Temperament is more stable — particularly the extremes. A child in the highest quartile for negative emotionality is considerably more likely than a low-scoring child to show anxiety and emotional reactivity as an adult, even if the specific expression changes dramatically.
Personality shows more change over the lifespan, particularly on dimensions like Conscientiousness (which tends to increase through adulthood) and Neuroticism (which tends to decrease). But change is gradual, occurs mostly in response to major life experiences, and operates within limits partly set by the underlying temperament.
This matters for how you interpret personality assessment results. A score on Neuroticism is not a verdict — it reflects a current profile that's partly wired and partly learned. The wired part is harder to change directly; the learned part responds to deliberate work on emotional regulation, cognitive patterns, and the situations you habitually put yourself in.
Clinical and Practical Applications
Understanding temperament is particularly valuable in several contexts:
- Child development and parenting — recognising that difficult temperament traits (high intensity, low adaptability, withdrawal tendencies) are constitutional rather than chosen helps parents respond to the child rather than against them. Goodness-of-fit research consistently shows that matching parenting approach to temperament produces better outcomes than trying to override it.
- Anxiety and emotional dysregulation — high negative emotionality is a temperament substrate for anxiety disorders. Treatment is more effective when it accounts for the biological baseline rather than treating the presenting anxiety as purely learned.
- Career fit — some job demands run directly against temperament. A person with low surgency and high threshold-for-stimulation needs will be consistently depleted by high-contact sales roles, regardless of how well they've learned to perform in them.
- Relationship dynamics — persistent conflicts often have temperament components: two high-intensity partners amplifying each other, mismatched rhythmicity producing scheduling friction, or one partner's high withdrawal tendency being read as rejection by a high-approach partner.
A free Jungian archetype test can reveal the patterns in how your personality currently expresses itself, which is a useful complement to understanding the underlying temperament that shapes those patterns.
Frequently Asked Questions
Can temperament be changed?
The underlying biological tendencies that define temperament are largely stable, particularly at the extremes. What changes is expression — how a temperament trait manifests given the coping strategies, values, and contexts a person develops. Someone with high negative emotionality can become a skilled emotional regulator; the underlying reactivity doesn't disappear, but its impact on behaviour diminishes considerably.
Are MBTI types the same as temperament types?
No. MBTI types are personality types — descriptions of characteristic patterns of perception and decision-making. They overlap loosely with temperament but are not the same construct. Keirsey's Temperament Sorter, sometimes associated with MBTI, uses the word "temperament" differently from the developmental psychology tradition.
What is "difficult temperament" in infants?
Thomas and Chess described a cluster of traits — low rhythmicity, high intensity, withdrawal tendencies, low adaptability, and negative mood — as "difficult temperament." It predicts harder parenting experiences and somewhat greater risk of adjustment problems, but is not deterministic. The label was later criticised for its value loading; "slow-to-warm-up" children, for example, often develop well in patient environments.
How much of personality is genetic?
Twin roughly 40–60% of variance in major personality dimensions is heritable. The remaining variance is environmental — partly shared family environment, partly unique individual experiences. The genetic component is expressed through temperament; personality as a whole reflects genetic plus developmental factors.
Does personality change much in adulthood?
Research consistently shows gradual personality change across adulthood, with Conscientiousness and Agreeableness typically increasing and Neuroticism and Openness somewhat decreasing after middle age. Major life events — serious illness, significant relationships, career transitions — can produce more rapid change. But the core profile tends to remain recognisable across decades.