Question

How do genetic and environmental factors work together to influence temperament?

Answer 1

Three dimensions of temperament -- difficult temperament, unadaptablility and unsociability -- were assessed in the first year of life by maternal interview in twins born in Puerto Rico during 2001 and 2002. Eight hundred and sixty-five eligible mothers (80%) were traced and interviewed. Model-fitting results showed that additive genetic factors and the individual specific environment contributed to variation in all three dimensions. In addition, the pattern of variances and correlations suggested that sibling contrast effects influence ratings of difficult temperament. Moderate effects of the shared environment contributed to ratings of adaptability and sociability. There was a significant genetic correlation between difficult temperament and unadaptability. Genetic and environmental effects do not differ significantly between boys and girls. The study is the first population-based study of Puerto Rican twins and one of few to attempt the assessment of behavior in the first year. Preliminary results for difficult temperament and sociability were consistent with those in other populations and ages. In contrast, a significant effect of the shared environment on the temperamental trait of unadaptability has not been reported previously.

A child with a short attention span and who is very impulsive is likely to experience difficulties in learning situations either at home or at pre-school groups (Tizard and Hughes, 1984). This example shows that temperamental differences may have a pervasive effect on children’s cognitive and social development through their impact on behavioural control and responsivity. In older children Keogh (1982) has identified a three factor model of temperament that is related to behaviour in school and which has implications for learning. The factors are Task Orientation, Personal-Social Flexibility and Reactivity.

Clearly factors such as task orientation will have a direct impact on the child’s ability to gain from learning experiences. Other temperamental influences will have more indirect effects on academic attainment. For example, reactivity is more likely to influence pupil–teacher and pupil–pupil interaction and thereby the social context within which learning takes place.

Direct effect of child temperament on parents
One of the central concepts in current thinking about child development is that of the child influencing its own development, i.e. not just being a passive receiver of externally determined experiences. Bell (1968) and Sameroff and Chandler (1975) are widely recognized as bringing this transactional model to the fore. Under this model the child plays a significant role in producing its own experiences both directly by its own selection of activities but, more importantly for the young child, by the influence its behaviour has upon caretakers (Sameroff and Fiese, 1990).

Indirect effect via ‘goodness of fit’
There has been a strand of thinking linked with the study of temperament that has emphasized that the significance of individual differences in temperament has to be considered in relation to specific environments. A child who is very low on adaptability and very high on rhythmicity using will have a more aversive experience if cared for by parents who are very erratic in their pattern of child care. The same child will be well suited to parents who are more regular in their routines of eating and sleeping. This suggests that the impact of temperament on development has to be analysed as an interaction between the child’s characteristics and features of the environment including parenting.
There have been several temperament theorists who have taken this position.

One of the most extensive research studies with this goodness of fit orientation is that of Lerner and colleagues:

The ‘goodness of fit’ concept emphasizes the need to consider both the characteristics of individuality of the person and the demands of the social environment, as indexed for instance by expectations or attitudes of key significant others with whom the person interacts (e.g. parents, peers or teachers). If a person’s characteristics of individuality match, or fit, the demands of a particular social context then positive interactions and adjustment are expected. In contrast, negative adjustment is expected to occur when there is a poor fit between the demands of a particular social context and the person’s characteristics of individuality. (Lerner, et al., 1989, p. 510)

As an illustration of this notion of the goodness of fit between the child’s temperament and parental behaviour Lerner et al. (1989) discussed some of the evidence concerning temperament and maternal employment outside the home. Of course a wide variety of social and economic pressures will be influencing the decision to work outside the home. However, in addition they suggest that there could be two plausible routes whereby difficult temperament could influence mothers’ decisions on whether to work outside the home. The first could be that mothers find the problems of rearing the child with difficult temperament too aversive and therefore opt to go out to work to avoid the hassles of daily child care.

The second route could be that the difficult child is so unpredictable in its eating and sleeping habits and protests intensely when left with unfamiliar people that the mother feels constrained not to go out to work because the child cannot fit in with the externally required constraints of the mother attending the work place at fixed times for fixed periods.

The goodness of fit approach suggests that which of these processes operates will depend on the fit between the child’s temperament and the mother’s tolerance. It will not be possible to predict the consequences of difficult temperament on the mother’s decision to return to work with knowledge of her attitudes towards child rearing and towards time keeping at work.

Lerner and Galambos (1985) found that mothers of children with difficult temperament tended to have more restricted work histories than other children.

One problem with this finding is that mothers’ reports on their infants’ ‘difficulty’ may be biased by factors that also affect work performance, such as depression. Hyde et al. (2004) examined this possibility in a study which found that the consensus infant temperament judgements of fathers and mothers were still a good predictor of mothers’ work outcomes. This study also found evidence that a mediating factor between infant temperament and maternal work outcome is maternal mood: difficult infants are likely to make mothers more depressed and diminish their sense of competence, thus affecting their work performance. The Lerner and Galambos (1985) study also found that it seemed to be harder for parents to make satisfactory day-care arrangements for difficult infants.


Indirect effect via susceptibility to psychosocial adversity
Temperament may also be related to differences in vulnerability to stress. Not all children are adversely affected by the experience of specific stresses, such as admission to hospital. Pre-school children repeatedly hospitalized are at risk for later educational and behavioural difficulties but only if they come from socially disadvantaged backgrounds (Quinton and Rutter, 1976).

It has proved more difficult to establish whether temperament does influence susceptibility to adverse experiences. Dunn and Kendrick (1982) have shown that an older child’s response to the arrival of a new sibling is systematically related to their temperament as measured whilst their mother was pregnant.

Most children respond to this event with some upsurge of behavioural disturbance, such as an increase in demands for parental attention or in crying. Which behavioural response is shown is related to prior temperament. Unfortunately their data do not suggest any clear pattern of any one aspect of temperament being more significant than any other. However, there were indications that increases in fears, worries and ‘ritual’ behaviours were associated with a high degree of temperamental Intensity and Negative Mood measured before the arrival of the second child.


Indirect effect on range of experiences
An important aspect of the transactional model of development is that as children become older they increasingly come to influence the range of environments they encounter and the experiences these create. During infancy, children with different temperament styles evoke different responses from the people they encounter, for example, active, smiling infants are more likely to be smiled at and played with than passive unresponsive infants. As children become more mobile and more independent they are able to select for themselves between alternative experiences, for example, a shy, behaviourally-inhibited child may avoid social encounters. This may accentuate temperamental characteristics: the avoidance of meeting other people prevents the child from becoming socially skilled and therefore more reluctant to engage in social behaviour in the future. This may have a wider impact on their development. For example, Rutter (1982) has demonstrated the way impulsive, active children are more likely to experience accidents, presumably as a result of their selecting more risky environments to play in.

These alternative mechanisms for the impact of temperament on the environments the child experiences can be classified into three types of gene-environment correlation. Scarr and McCartney (1983) have suggested that children’s genetic make-up comes to influence the environments they experience through three routes. These can be illustrated for temperament. One is passive gene-environment correlations which are produced when the child is being cared for by parents who share similar temperaments to the child. A child with a high intensity of reaction is more likely than other children to be cared for by a parent who has a similarly high intensity of reaction. Such parent–child pairs are likely to be creating experiences for the child which will be eliciting much aversive stimulation for the child. Evocative gene environment correlations are created when the child’s behaviour evokes specific types of responses from carers. This was illustrated in the earlier example of sociable children evoking more social stimulation from carers. The third type is active gene-environment correlation which arises from the child actively seeking environments that suit its behavioural predispositions. Children with a low threshold of responsiveness are likely to seek less extreme and more predictable environments.

An important feature of the Scarr and McCartney theory is that they propose that as the child becomes older the mix of these correlations will change. Initially the passive and evocative correlations will dominate. The evocative effects will remain fairly constant. The significance of passive effects decline in importance as the child encounters a wider range of people than just primarily the parents. Clearly active gene-environment effects are likely to become dominant as the child has greater and greater freedom to select its own activities.

Summary

• Temperament can directly influence other aspects of development, for example, attentional variation has an impact on cognitive development.
• Temperamental variation influences the parent’s response to the child.
• The goodness of fit between a child’s temperament and parental style can have an impact on the child’s attachment and long-term social adjustment.
• Temperament can influence a child’s vulnerability to the adverse effects of life events.
• Temperament can have a marked effect on the type and range of experiences to which the child is exposed.

The results of this investigation suggest that any individual characteristic of either child or mother may be less important than the relationship context within which that characteristic occurs.