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Chapter

CH2 Textbook Notes


Department
Psychology
Course Code
PSY240H1
Professor
S.Cassin

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CHAPTER 2 CONTEMPORARY THEORIES OF ABNORMALITY
- theory: a set of ideas that provide a framework for asking questions about a phenomenon, as
well as gathering and interpreting information about that phenomenon
- Albert Ellis suffered a fear of public speaking
- he believed his fears were due to irrational beliefs
- other theories would suggest alternative causes of his fears
- biological approach would suggest his symptoms were caused by a biological
factor e.g. genetic vulnerability to anxiety
- psychological approach suggests symptoms are rooted in psychological factors
e.g. belief system, early childhood experiences
- social approach would look at his interpersonal relations and social environment
- most theories over history searched for one factor that causes people to develop a disorder
- contemporary theorists recognize that there are often many pathways that lead to the
development of a specific disorder
- vulnerability stress model: a person must carry a vulnerability to the disorder in order to
develop it
- it can be biological (genetic predisposition), psychological (personality trait), social factor
(poor interpersonal relationships)
- to develop the disorder, person must experience some type or stress or trigger
- biological (illness), psychological (violation of trust), social factor (traumatic event)
- feedback effects: change in one factor result in changes in a second factor which feed back to
change the first factor again
Biological Approaches
Structural Brain Abnormalities
- people who suffer damage to the brain (lesions) or who have major abnormalities in the
structure of the brain often show problems in psychological functioning
- location of structural damage influences the psychological problems one can have
- cerebral cortex: area involved in many advanced thinking processes
- hypothalamus: regulates eating, drinking, and sexual behaviour, influences basic emotions
- stimulation in certain areas produce pleasure whereas in other areas produce pain
- limbic system: collection of structures closely interconnected with the hypothalamus and
appear to exert additional control over some instinctive behaviours
- other major structures of the brain (figure 2.5 pg34)
- corpus callosum: bridge of fibres passing information between the two cerebral
hemispheres
- thalamus: relay centre for cortex; handles incoming and outgoing signals
- cerebellum: involved in balance and control of movement
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- medulla: responsible for regulating largely unconscious functions e.g. circulation,
breathing
- pons: involved in sleep and arousal
- reticular formation: network of neurons related to sleep, arousal, and attention
- spinal cord: responsible for communication between brain and rest of body; involved with
simple reflexes
Biochemical Causes of Abnormality
- neurotransmitters: biochemicals that act as messengers, carrying impulses from one neuron
(nerve cell) to another in the brain and in other parts of the nervous system
- each neuron has a cell body and dendrites which receive impulse from adjacent neurons
- impulse then travels down the length of the axon to small swellings at the ends called
synaptic terminals
- there is a slight gap between the synaptic terminals and adjacent neurons called the
synaptic gap, or synapse
- neurotransmitter is released into the synapse and then binds to receptors, molecules on
membranes of adjacent neurons
- binding stimulates adjacent neurons to become more negatively or positively charged
Neurotransmitter Theories
- too much or too little of certain neurotransmitters in the synapses causes specific types of
psychopathology
- amount of neurotransmitter in synapse can be affected by
- reuptake: when the initial neuron releasing the neurotransmitter reabsorbs the
neurotransmitter, decreasing the amount left in the synapse
- degradation: when the receiving neuron releases an enzyme into the synapse breaking
down the neurotransmitter into other biochemicals
- both happen naturally, when one or both malfunction, result in abnormally high/low levels
- psychological symptoms may also be linked to the number and functioning of receptors for
neurotransmitters on the dendrites
- if there are too few receptors or receptors arent sensitive enough, the neuron will be
unable to make adequate use of the neurotransmitter available in the synapse
- if there are too many receptors or they are too sensitive, neuron may be overexposed
- serotonin: regulates emotions and impulses e.g. aggression
- travels through many key areas of the brain
- dopamine: prominent in areas of brain that regulate our experience of reinforcement or
rewards, affected by substances that we find rewarding
- important to functioning of muscle systems
- norephinephrine: produced mainly by neurons in brain stem
- cocaine and amphetamines prolong the action by slowing its reuptake process
- low levels cause a persons mood level to be depressed
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- gamma-aminobutyric acid (GABA): inhibits action of other neurotransmitters
- thought to play an important role in anxiety symptoms
Endocrine System
- system of glands producing chemicals, hormones, which are released directly into the blood
- a hormone carries messages throughout the body, potentially affecting mood, levels of
energy, and reaction to stress
- pituitary gland: “master gland that produces the largest number of different hormones and
controls secretion of other endocrine glands
- hypothalamic-pituitary-adrenal axis (HPA axis) is the relationship between the pituitary gland
and the hypothalamus
Genetic Factors in Abnormality
- behaviour genetics: the study of the genetics of personality and abnormality
- concerned with (1) to what extent are behaviours inherited (2) what are the processes by
which genes affect behaviour?
- most disorders arent the result of single faulty genes but of combinations of altered genes
- polygenic process: it takes multiple genetic abnormalities coming together in one individual to
create a disorder
- scientists use three basic types of studies to determine the heritability of a disorder
Family History Studies
- genetically transmitted disorders should show up more often in families of people with the
disorder than in families of people without it
- scientists first identify people who clearly have the disorder in question, probands
- also identify a control group of people who clearly dont have the disorder
- they then trace the family pedigrees of the individuals in these two groups and determine
how many of their relatives have the disorder
- problem: families also share environment and as a result, environmental stresses
Twin Studies
- if a disorder is determined entirely by genetics, when on monozygotic (MZ) twin has a disorder,
the other should always have it
- concordance rate: the probability that both twins have the disorder if one twin has the disorder
- concordance rate for disorders transmitted partially by genetics should be higher in MZ
twins than for DZ twins
- however studies dont fully separate genetic factors from environmental factors
Adoption Studies
- researchers first identify people who have the disorder of interest who were adopted shortly
after birth
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