THEME 7
I. CONCEPTUAL ISSUES: PERSONALITY DEVELOPMENT, CHANGES AND STABILITY
What is personality development?
Personality development can be defined as the sum of both continuities and consistencies in
people over time and the way people change over time.
There are two important types of stability over time:
• rank order stability
• mean level stability
1. Rank Order Stability = maintaining one's rank in a group of people
↳ if a person maintains their traits (ex.: maintaining the same level of
extraversion), it means they will maintain their rank in the group(s) they are part of
BUT, if they don't and their 'rank' changes (ex.: due to becoming introverted, they are demoted),
then the group will experience 'rank order instability / change'
2. Mean Level Stability = the mean level of a personality trait in a group of people
stays consistent across time
↳ ex.: political views may stay consistent across time, but they may also
change from one side to the other which means that if they change, then this is a
display of 'mean level change'
!!! Personality changes is characterized by two aspects:
• the changes happen at an internal level for the person
• the changes are relatively enduring over time, not temporary
II. PERSONALITY STABILITY OVER TIME
1. Stability in Temperament During Infancy
The traits studies in infants are mostly under one umbrella term: temperament.
Most researchers describe temperament as 'individual differences that emerge early in life and
re likely to have heritable basis and are involved in emotionality and arousability'.
o An important name is studies concerning infants is Mary Rothbart, who studied
infants during their first 12 months of life. The study used the data the mothers /
caretakers of the infants provided in regards to 6 aspects related to temperament:
• activity level (physically)
• smiling and laughter
• fear (of novel stimuli)
• distress to limitations (being refused food or access to specific objects)
• soothability
, • duration of orienting (how long an infant would focus on one thing without any
disturbances)
Findings:
• activity levels and smiling are the most stable traits
• personality traits become more stable towards the end of infancy
One specific limitation is very important: the mothers / caregivers could have had a specific
perception of the infant's behavior → subjective conception of the kid
!!! Conclusions:
o stable individual differences appear very early in life
for most temper related variables, they have moderate stability over the
first year of the infant’s life
o stability tends to be more pronounced over short periods of time
2. Stability During Childhood
• actigraph = motion recorder device used on kids (attached on a limb) for experiments
which records the magnitude and frequency of movement at set intervals
↳ the data from these devices complement the mostly valid data that researchers and
parents provide through observations
• stability coefficient (test-retest reliability coefficient) = correlation obtained from
measures done at two different points in time → found in the 'Age-to-age' column
• validity coefficient = the correlation between different measures taken at the same time of
the same trait → 'Actigraph' columns
** study of MZ and DZ twins from 2 to 3 years old
I. CONCEPTUAL ISSUES: PERSONALITY DEVELOPMENT, CHANGES AND STABILITY
What is personality development?
Personality development can be defined as the sum of both continuities and consistencies in
people over time and the way people change over time.
There are two important types of stability over time:
• rank order stability
• mean level stability
1. Rank Order Stability = maintaining one's rank in a group of people
↳ if a person maintains their traits (ex.: maintaining the same level of
extraversion), it means they will maintain their rank in the group(s) they are part of
BUT, if they don't and their 'rank' changes (ex.: due to becoming introverted, they are demoted),
then the group will experience 'rank order instability / change'
2. Mean Level Stability = the mean level of a personality trait in a group of people
stays consistent across time
↳ ex.: political views may stay consistent across time, but they may also
change from one side to the other which means that if they change, then this is a
display of 'mean level change'
!!! Personality changes is characterized by two aspects:
• the changes happen at an internal level for the person
• the changes are relatively enduring over time, not temporary
II. PERSONALITY STABILITY OVER TIME
1. Stability in Temperament During Infancy
The traits studies in infants are mostly under one umbrella term: temperament.
Most researchers describe temperament as 'individual differences that emerge early in life and
re likely to have heritable basis and are involved in emotionality and arousability'.
o An important name is studies concerning infants is Mary Rothbart, who studied
infants during their first 12 months of life. The study used the data the mothers /
caretakers of the infants provided in regards to 6 aspects related to temperament:
• activity level (physically)
• smiling and laughter
• fear (of novel stimuli)
• distress to limitations (being refused food or access to specific objects)
• soothability
, • duration of orienting (how long an infant would focus on one thing without any
disturbances)
Findings:
• activity levels and smiling are the most stable traits
• personality traits become more stable towards the end of infancy
One specific limitation is very important: the mothers / caregivers could have had a specific
perception of the infant's behavior → subjective conception of the kid
!!! Conclusions:
o stable individual differences appear very early in life
for most temper related variables, they have moderate stability over the
first year of the infant’s life
o stability tends to be more pronounced over short periods of time
2. Stability During Childhood
• actigraph = motion recorder device used on kids (attached on a limb) for experiments
which records the magnitude and frequency of movement at set intervals
↳ the data from these devices complement the mostly valid data that researchers and
parents provide through observations
• stability coefficient (test-retest reliability coefficient) = correlation obtained from
measures done at two different points in time → found in the 'Age-to-age' column
• validity coefficient = the correlation between different measures taken at the same time of
the same trait → 'Actigraph' columns
** study of MZ and DZ twins from 2 to 3 years old
