First, there are different approaches of studying ‘temperament’ in children:
1) Behavioural Approach
Thomas and Chen proposed that children differ in 9 ways (activity, rhythm, withdrawal, adaptability, responsiveness, raction, mood, distraction) which can be merged to 3 main types: difficult, easy, slow to warm up
2) Criterial Approach
Certain qualities that are a) present in related mammals b) present from birth until the present and c) adaptive and necessary for survival (= genes) have been identified in kids. These translate to emotionality (fear), activity (fight), sociality (help) (and can also be mapped to the types described by the behavioural approach; slow to warm up, difficult, easy)
3) Psychobiological Approach
Many kids were studied with a temperament scale, factor analysis found that they differed in reactivity. Behaviour was linked to neurobiology. They looked at kid’s responses to novel situations and their control. 3 factors were found: surgency (i.e. outgoing or extroverted, maps on to E, A), negative affectivity (emotionality, maps on to N), effortful control (control emotions and hold back, whether a kid is quiet and shy, maps on to C).
4) Biological Approach
Kagan found two types of children: uninhibited, unreactive (extroverted, okay in novel situations), and inhibited, reactive (introverted, melancholic, fears new stimulus). This reflects the distinction between previous mentioned ‘easy’ and ‘difficult’ kids.
A longitudinal Dunedin Study found the following
This study shows that traits are somewhat stable.
There are two theories for the stability of traits: a) genes, b) environment (people select reinforcing environments, others behave in ways that perpetuate one’s traits)
Personality can change but social factors help with stabilising it. Not age changes personality, but the environment does (when younger, environments tend to change more than when older and settled down). Some changes in personality may be due to major life events (e.g. getting married, having a child, etc).