CHAPTER TWO Causes of Abnormal Behavior: A Systems Approach.

CHAPTER TWO

Causes of Abnormal Behavior: A Systems Approach

Causes of Abnormal Behavior

• What are paradigms?

• 4 basic psychological paradigms

• Behavior genetics

• Systems theory

What is a Paradigm?

A set of shared assumptions about:

•the substance of a theory

•how scientists should collect data and test theoretical propositions.

• What are paradigms?What are paradigms?

• 4 basic psychological paradigms

• Behavior geneticsBehavior genetics

• Systems theorySystems theory


4 Basic Psychological Paradigms

• Psychodynamic

• Cognitive-Behavioral

• Humanistic

• Biological

Which paradigm is correct?Which paradigm is correct?The blind men and the elephantThe blind men and the elephant

Which paradigm is correct?

Two answers:

• Individually, all of them • Some or all of them together

• This approach is a Systems theory or biopsychosocial approach



• 4 basic psychological paradigms4 basic psychological paradigms

• Systems theory

• Behavior geneticsBehavior genetics

Systems Theory: Outline

• Definition

• Causality

• Levels of Analysis

Systems Theory: Definition

• No one paradigm offers the “right” approach. Systems theory integrates evidence from the biological, psychological and social domains.

• The centerpiece of systems theory is:Holism: whole=more than the sum of parts

e.g. playing in a sports team (basketball, volleyball)

The opposite of holism is:Reductionism: whole = sum of its parts.

e.g. playing in a sports team (gymnastics, wrestling)

• Diathesis-Stress Model• Diathesis: existing vulnerability that

precedes stressor

• Stress: any event that triggers the onset of disturbance

• A diathesis may or may not be biological, and a stressor may or may not be environmental.

Systems Theory: Causality


Equifinality: different causes for same disorder

Death of parentLoss of jobChange in brain chemistry

DepressionDepressionDepression


Multifinality: same causal factor but different outcomes

Earthquake

Phobia

PTSD

Depression

Reciprocal causality: causality is bidirectional.

Parent’s behavior Child’s behavior


Systems Theory: Levels of Analysis

• Systems theory integrates evidence from biological, psychological and social domains of behavior (not additive)

• Different paradigms operate at different levels of analysis when explaining human behavior:

e.g., neuron, individual, couple, family,

community, culture.

Multidimensional Model

• 50% of psychology due to biological factors, 50% due to social factors??

Misleading…

• Because interactions between factors are more important


• 4 basic psychological paradigms4 basic psychological paradigms

• Systems theorySystems theory

• Behavior genetics


• Behavior genetics • the study of genetic contributions to

the development of normal and abnormal behaviors

• Genotype• total genetic make-up (genetic profile)

Biological Paradigm: Behavior Genetics

• Phenotype• observable expression/characteristics

of genotype (such as weight and eye color)

• Genotype is fixed at birth, but phenotype is a result of genotype and experiences.


Genotype vs. Phenotype

• There are three different approaches to studying behavior genetics.• Family incidence studies • Twin studies • Adoption studies


Family Incidence Studies: Do disorders run in families?

• Researchers identify theindex person in a family or a proband

• Then examine the proportion of family members that suffer from different disorders relative to this person (the proband)


Proband %family MDD %family Schz.

MDD 30 0.5Schizophrenia 10 10No diagnosis 10 0.5

Hypothetical Data Set


*Are members of my family at risk for having a disorder given that I have the disorder?

Proband %family MDD %family Schz.

MDD 30 0.5Schizophrenia 10 10No diagnosis 10 0.5

Hypothetical Data Set


Twin Studies: Logic

Twin studies• Concordance, simply

means “agreement”• Depressed Twin A = Depressed

Twin B• Example: in a study of 100 Twins, if

60% of all the twins both have depression, then the concordance rate is 60%

• MZ twins have 100% genetic overlap. • On average, DZ twins have 50%

genetic overlap (like typical siblings)

• Assumes that pairs of MZ twins are not treated any more alike than are pairs of DZ twins

• But MZ twins may be treated more alike because they look alike…

Twin Studies: Shortcoming

Twin Studies: Twins Raised Apart (MZ twins)

• To account for the fact that MZ twins may be treated more similarly than DZ • Different adoptive families (= different

environment or different treatment)

• Differences in concordance rates cannot be attributed to MZ twins having a more similar environment than DZ• Can’t assume similar treatment of MZ twins, so

if differences are found they may be attributed to environmental factors…

Behavior Genetics: Adoption Studies

• Compare adopted children with and without family histories of a disorder

• Compare concordance rates with biological and adoptive parents to see which is higher

• Genetic and environmental factors

Adoption Study: Disorder X

Proband % Adopted-Away children

(Biological Parents) with Disorder

With Disorder X 20

Without Disorder X 10




With Disorder X 20

Without Disorder X 10

* Children of Bio Parents with Disorder X are at a higher risk, so there is a Genetic Influence

Adoption Study: Disorder Y



With Disorder Y 10

Without Disorder Y 10




With Disorder Y 10

Without Disorder Y 10

* Children of Bio Parents with Disorder Y are NOT at a higher risk, so there’s NO Genetic Influence


% biological % adoptive Proband parents with parents with

Disorder X Disorder X

Adoptees with 20 10Disorder XAdoptees without 10 10Disorder X



Disorder X Disorder X

Adoptees with 20 10Disorder XAdoptees without 10 10Disorder X

* Bio Parents of children with Disorder X are at a higher risk compared to Adoptive Parents, so there is a Genetic Influence



Disorder Y Disorder Y

Adoptees with 10 10Disorder YAdoptees without 10 10Disorder Y



Disorder Y Disorder Y

Adoptees with 10 10Disorder YAdoptees without 10 10Disorder Y

* Bio Parents of children with Disorder Y are NOT at a higher risk compared to Adoptive Parents, so there’s NO Genetic Influence

Adoption Study: Disorder Z


Disorder Z Disorder Z

Adoptees with 20 10Disorder ZAdoptees without 20 10Disorder Z

Adoption Study: Disorder Z


Disorder Z Disorder Z

Adoptees with 20 10Disorder ZAdoptees without 20 10Disorder Z

* Bio Parents of children with Disorder Z are NOT at a higher risk compared to Bio Parents of children without Disorder Z, so there’s NO Genetic Influence

• Genes not sufficient to account for development of any psychological disorder. We need to study environmental factors

• Gene-environment interactions:Reciprocal gene-environment model• Genes might influence the environment

that people seek out. Environmental factors may bring out a genetic predisposition. The two are not independent.


Misinterpretation of Behavior Genetics

INCORRECT ASSUMPTIONS

• If there is a genetic influence, a disorder is inevitable

• If a behavior or characteristic is genetically influenced, it cannot be changed

• If there is a genetic influence, a gene must be directly responsible for the behavior

•i.e., environmental factors are often necessary to trigger the expression of genes

•e.g., some people have genetic predisposition to alcohol, but they are still able to change

• polygenetic + environmental stress

• Biology can be influenced by psychology!

• Biological causes do not necessarily require biological treatment

• Today most psychologists view disorders as being caused by multiple factors.

Biological Perspective

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CHAPTER TWO Causes of Abnormal Behavior: A Systems Approach.

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