Psychological assessment 9, 349-360
Harkness, A. R., & Lilienfeld, S. O. (1997)
Individual differences science for treatment planning: personality traits

The authors of this article argue that individual differences research requires the inclusion of personality trait assessment for the construction and implementation of any treatment plant that would claim to scientific status.
Four important gains for treatment planning that can be realized from the science of individual differences in personality

• Knowing where to focus change efforts
• Realistic expectations
• Matching treatment to personality
• Development of the self

Science should guide treatment planning

The fundamental rule of treatment planning

Our fundamental rule of treatment planning states that the plan should be based on the best science available.
These guides constitute standards of the profession and are legally essential in determining when practice is adequate and when it falls short.
The therapist should be well informed regarding recent scientific findings, even if those findings were not emphasized in the psychologist’s school or practice settings.

Treatment planning then and now: a picture completion problem

Any planning was vulnerable to clinical hermeneutics error.

• In adopting the patient’s perspective, the therapist can lose track of the actual degree of pathology and begin to underestimate it

Since the 1980s, with the adoption of the Neo-Kraepelinian diagnostic rubrics, we have experienced a restructuring of much of clinical activity.
The Neo-Kraepelinian prescription entails

• Ascertainment of facts to determine the presence or absence of relatively explicit diagnostic criteria
• The making of differential and multiaxial diagnoses using the categories and language of the current DSM
• Differential selection of treatment guided by the differential diagnosis

Criticism of current practice is that diagnosis, in the absence of a personality individual differences formulation, misses the point that signs and symptoms that appear under the heading of ‘presenting complaints’ or ‘targets of treatment plan’ may often be manifestations or sequellae of personality treats.
The features the diagnostician focuses on may be consequences of

• Extreme levels of personality traits
• Especially problematic configurations of trait levels
• Extreme adaptations to personality traits or their configural properties

Features of disorders that have considered causal may instead turn out to be simply correlated properties when examined from an individual differences perspective.

A personality individual differences primer for treatment planners

One theoretical viewpoint on traits: constructive realism

Constructive realism: the falsifiable assumption that traits are real, they exists separately from the observer, and they are not be be confused with constructs or measures.

Traits exist in individuals, but traits lead to population concepts.

• Trait level: the specific disposition each person’s psychophysical systems give rise to
• Trait dimension: what individual levels constitute across the composite of the population
  You can examine: what are the major dimensions along which people differ?

Some major research findings on traits

There are major replicable trait dimensions, which are organized hierarchically.
Lower order traits becomes the variance of broader, higher order traits.

Three broadgauge trait dimension factors at the Eysenck and Telegen level

• Extraversion
• Neuroticism
• Constraint

All three of these individual differences dimensions have substantial genetic influence and are associated with a variety of forms of psychopathology.
There is compelling evidence that these personality traits exhibit considerable long-term stability in adulthood.

Where do personality traits come from?

Environmental effects can be subdivided into two sources:

• Shared
  Environmental factors that increase familial resemblance for a trait
• Unshared
  Environmental factors that do not promote familial resemblance for a trait

Genetic effects can be subdivided as well.

Treatment planners should know about four important issues addressed by the powerful research methods of behaviour genetics

• The heritability of personality traits
• Recent initial findings on the source of stability of personality traits
• Gene-environment correlations
• The apparent impotency of shared family environmental experienced in shaping personality traits

Heritability of personality traits

Heritability: the proportion of the phenotypic variance in a trait that is attributable to genetic influences.
Because it is based on variances, it is a population, not an individual, concept.
It does not necessarily imply a lack of malleability.

Reaction range of genotypes: the extent to which their phenotypic expression can be modified by environmental factors.

Initial findings on the source of personality trait stability

Much of the stability of personality traits stems from genetic factors, whereas change arises primarily from unshared environmental factors.

Multiple genetic mechanisms underlie the stability of personality traits.
These various genetic mechanisms influence behaviour through causal chains of differing lengths.
Some genetic mechanisms have an effect on behaviour through relatively direct biological influences of genes on temperamental and personality variables.

Active gene-environment (g-e) correlation.
Nature via nurture.
Genes can only affect behaviour through causal chains differing in the degree of indirectness.

Gene-environment correlations

Individuals with differing genotypes are not randomly assigned to environments.
In the case of active g-e correlation, it is through the agency of the person that environments are selected or created that are consonant with the genotype.

Wachtel suggested that psychotherapeutic interventions should be targeted toward the choices of current environmental stimuli, rather than toward the underlying disposition created, in his view, by early developmental experiences.

Two other forms of g-e correlation

• Passive
  When parents provide both genes and environmental influences that contribute to the development of a characteristic in their children
  Early in life
• Reactive
  When other individuals respond to behaviour produced by the individual’s genotype in characteristic ways.
  Throughout the life span
• Active
  Increase from childhood to adulthood
  Results from the increase in individuals’ capacity to seek out, select, and create niches that are consonant with their genetic dispositions.

The unexpected weakness of shared family influence in shaping personality traits

There is a negligible role of shared environmental influences on most or all personalty traits in adulthood.
Common environmental experiences do not contribute substantially to personality resemblance.
Although shared environmental influences may exert a lasting influence on personality at the extremes of parenting practice, at the average sharing family life does not strongly promote personality similarity of family members.

Basic tendencies and characteristic adaptations

For any level of an individual differences, there are many potential life adaptations: equipotentiality.
Markedly different life adaptations can reflect the same or similar underlying personality dispositions.

• Basic tendencies
  The underlying dispositions
• Characteristic adaptations
  The concrete habits, attitudes, roles, relationships and goals that result from the interaction of basic tendencies with the shaping forces of the social environment

For any level of basic tendency, there are many potential characteristic adaptations, and these adaptations vary greatly in social cost, personal suffering, and growth or stagnation.

Adaptation involves not only coping with and creating external circumstances but also adaptation to oneself, to one’s own basic tendencies.

An important implication of the basic tendency versus characteristic adaptation distinction is that one may expect moderate, rather than extremely high, correlations between trait measures and categories of psychopathology.
Some diagnostic criteria sets are in fact complex descriptions that mix together basic tendencies and characteristic adaptations.
Relatively pure dispositional measures may show only moderate relations with diagnostic categories.

Trait-informed treatment planning: Knowing where change is possible, realistic expectations, matching treatment to personality, and growing a self

There are four major benefits

• Better information would be available on where to target change effort
• More realistic expectations for change would be generated
• There is the possibility of matching treatments to personality
• Opportunities for the patient’s increased self-knowledge are created

Knowing where change is possible

Personality assessment helps decide if problems ware intimately linked with a person’s broad personality dispositions or whether they are more circumscribed.

• Simple problems involve situationally specific and transitory habits that are primarily products of current environmental contingencies
• Complex problems involve cross-situationally pervasive signs and symptoms reflecting long-term patterns of adjustment
  Can be viewed largely as manifestations or consequences of enduring personality traits

The distinction between simple and complex problems is presumably one of degree.
Assessment allows the treatment planner to ascertain where the problem stands on the simple-complex continuum.

Another way in which the individual differences perspective helps to target change efforts involves focusing those efforts on characteristic adaptations rather than on basic tendencies.
The main goal is to help patients find more promising characteristic adaptations.
These new characteristic adaptations should be constructed with sensitivity to the patient’s basic tendencies.

It is critical for treatment planners to realise that the causal impotence of shared family environmental influences may apply only to basic tendencies, not to characteristic adaptations.
Shared influence processes may play an important role in the phenotypic expression of dispositions.
Therapists can help patients select and construct social worlds consistent with themselves, but with higher potential for health and growth.
The adaptations that are created are consonant with their basic tendencies.

Realistic expectations

Individual differences science is essential for providing realistic prognoses for therapy.

Matching treatment to personality

The notion that people actively select and create environments that support, maintain, and amplify their personalty traits has important implications for treatment selection

• If one seeks to have a patient stay in therapy, matching treatment to personality offers a strategy

Growing a self

A person with more comprehensive self has greater resources, options,and capacities to deal with tendencies.
A comprehensive, reality-based model of the self offers new resources for mental health.