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Chapter 2

TEXTBOOK Chapter 2 - Theoretical Perspectives on Abnormal Behaviour

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University of Toronto Mississauga
Hywel Morgan

Notes From Reading C HAPTER  2: HEORETICAL  PERSPECTIVES  ON  ABNORMAL  BEHAVIOUR  (PGS. 23­47) The General Nature of Theories - Biological and psychodynamic formulations views dysfunctional behaviour as the product of forces beyond the individual’s control - Humanistic and existential approaches lay the responsibility for action and choices squarely on the shoulder of the individual - Behavioural and cognitive theories imply that a mixture of external and internal factors produce dysfunctions - The acceptance of the biological model encourages researchers to seek a physical basis for disorders, leads to the formulation of a diagnostic system that classifies people as disordered, and implies that physical interventions should be the treatments of choice - Behavioural perspectives leads researchers to seek environmental events that shape specific dysfunctional responses and emphasizes the classification of behaviours rather than of people - Interactionist explaination – behaviour as the product of the interaction of a variety of factors Levels of Theories - To state that a genetic defect or a single traumatic experience causes a mental disorder is to accept a single-factor explanation o Which attempts to trace the origins of a particular disorder to one factor o Most single-factor models reflect the primary focus of the researcher, theorist, or clinician rather than the belief that there really is a single cause - Single-factor theories often simply reflect the lack of current comprehensive knowledge of disorders - Interactionist explanations take into account the biology and behaviour of the individual, as well as the cognitive, social and cultural environment, given that any one component inevitably affects the other components - Scientific theories are valuable: o They integrate most of what is currently known about the phenomena in the simplest way possible (parsimony) o They make testable predictions about aspects of the phenomena that were not previously thought of o They make it possible to specify what evidence would deny the theory Testing Theories: The Null Hypothesis - Experiments are not set up to prove the worth of a theory but rather to reject (or fail to reject) what is called the null hypothesis - Null Hypothesis: proposes that the prediction made from the theory is false - Theories gain strength not just because of the evidence supports their predications, but primarily because alternative explanations are rejected The Search for Causes - Aims of theories about mental disorders are to: o Explain the etiology (causes or origins) of the problem behaviour o Identify the factors that maintain the behaviour o Predict the course of the disorder o Design effective treatments - Depression and anxiety are associated with restricted access to reflective processes or cognitive control associated with the anterior cingulated cortex, medial and lateral prefrontal cortex, and orbitofrontal cortex - Theories regarding the etiology of mental disorders: Biological, Psychodynamic, Behavioural or cognitive-behavioural theories, Cognitive theories examining dysfunctional thoughts or belief, Humanistic or existential theories examining interpersonal processes, Socio-cultural influences Notes From Reading C HAPTER  2: THEORETICAL  P ERSPECTIVES ON  ABNORMAL  BEHAVIOUR  (PGS. 23­47) - All of these systems work in concert and it is almost impossible (if not meaningless) to disentangle their influence - Reductionist thinking ignores the possibility that human behaviour in all its forms is a product of an array of features (biological, developments, cultural etc.) interacting Biological Models - Biological theories have primarily implicated dysfunctions in or damage to the brain (CNS), problems of control of one or another aspect of the peripheral nervous system, or malfunctioning of the endocrine system The Role of the Central Nervous System - The brain is estimated to have some 100 billion neurons and thousands of billions of glia cells - Brain activity is not located in a single area of the brain but as concentrated in one or more areas - Hindbrain primarily directs the functioning of the autonomic nervous system, which in turns controls primarily internal activities o Such as breathing, digestion, and cardiovascular functioning - Midbrain is the centre of the reticular activating system, which controls arousal levels (often called the sleep-wake centre) and thereby attentional processes - Forebrain controls thought, speech, perception, memory, learning, and planning - Some disorders have been shown to be directly linked to brain damage o Dementia that occurs in disorders such as Parkinson’s orAlzheimer’s is linked to the loss or ineffective functioning of brain cells o These losses of brain cell functioning can be transitory, but in many cases may result from various sources such as direct head injuries, diseases, or toxins - Neurotransmitters are the chemical substances that carry the messages from one neuron to the next in the complex pathways of nervous activity within the brain - There is a gap (called a synapse or synaptic celf) between axons (which carry the nerve impulse to the synapse) of one neuron and the dendrites (which pick up the activity from the first neuron) of neighbouring neurons - Certain neurons seem to be more sensitive to one or another type of neurotransmitter, and these neurons seem to cluster together, forming particular brain circuits - When neurotransmitters are released into the synapse, some will be taken up at the receptor sites on the dendrites and thereby activate or inhibit an impulse in the post-synaptic neuron - Abnormal behaviour can result from disturbances in neurotransmitter systems: o There may be too much or too little of the neurotransmitter produced or released into the synapse o There may be too few or too many receptors on the dendrites o There may be an excess or a deficit in the amount of the transmitter-deactivating substance in the synapse o The reuptake process may be too rapid or too slow - Any or all of these problems can cause either too much excitation or too much inhibition in the particular brain circuits, which may result in abnormal functioning - Disturbances in neurotransmitter systems are currently thought more likely to have general rather than specific effects - No doubt neurotransmitter activity affects behaviour, but behaviour also affects neurotransmitter activity - Brain Plasticity can be influenced by a number of experiences that occur pre- and postnatally through hormones, diet, aging, stress, disease, and maturation The Role of the Peripheral Nervous System Notes From Reading C HAPTER  2: THEORETICAL  PERSPECTIVES  ON A BNORMAL  BEHAVIOUR  PGS . 23­47) - The peripheral nervous system includes the somatic nervous system, which controls the muscles, and the autonomic nervous system (ANS) - ANS has two parts: the sympathetic nervous system and the parasympathetic nervous system - They typically function co-operatively to produce homeostatic (balanced) activity in a variety of bodily functions (heart rate, digestive, sexual arousal, breathing etc.) - During times of stress: o Sympathetic Nervous System readies the body for action (flight or fight) by, increasing heart rate, pupil size, faster breathing rate for more oxygen o Parasympathetic Nervous System shuts down digestive processes, since energy given to this function would be wasted in a time of emergency - Selye established the study called stress physiology; individuals differ in both the strength and the duration of their response to threat - An overreactiveANS may increase readiness to acquire phobias or other anxiety disorders - Individual differences in the regulation of various ANS and somatic nervous system functions may also play a part in disordered behaviour The Role of the Endocrine System - Aspects of the CNS interact with the endocrine system in a feedback loop that maintain appropriate levels of hormones circulating in the bloodstream - Hormones are chemical messengers that are secreted by various glands o These secretions maintain adequate bodily functioning and play an important role in the development of the organisms - Hypothalamus secretes “releasing” hormones that activate the pituitary gland - Increased levels of circulating sex steroids alert the hypothalamus and pituitary to shut down this activity - The hormones secreted by the pituitary influence hormonal production in the adrenal gland and the testes (in males) and the ovaries (in females) - The pituitary (“master gland”) releases many different hormones which activate other glands while others have a more direct action - Growth hormone promotes and regulates muscle, bone, and other tissue growth; - Two disorders are know to be related to malfunctioning endocrine glands o Cretinism: a disorder involving a dwarflike appearance and mental retardation is a result of a defective thyroid gland o Hypoglycaemia: results from the pancreas failing to produce balanced levels of insulin or glycogen, produces experiences that mimic anxiety - The Hypothalamic-Pituitary-Adrenal (HPA) axis is activated in response to stressors and involves an intricate system of communication between the hypothalamus, the pituitary gland, and the adrenal cortex - HPAaxis involves the release of the stress hormone cortisol into the bloodstream by the adrenal cortex o This hormone facilitates an individual’s response to short-term threat by producing a number of changes in the body - The HPAaxis is chronically activated in many individuals diagnosed with major depression, as well as individuals with anxiety disorder Genetics and Behaviour - Behaviours are the product of an interaction between these sources of influence - Behavioural genetics offers an insight into the biological bases of abnormal functioning - Genotype-Environment Interaction – Refers to the fact that genes may influence behaviours that contribute to environmental stressors, which, in turn, increase the risk of psycholopathology. Notes From Reading C HAPTER  2: HEORETICAL  PERSPECTIVES ON  ABNORMAL  BEHAVIOUR  (PGS. 23­47) In other words, there is a reciprocal relationship between genetic predisposition and environmental risk. - Behavioural research into the genetic bases of psychiatric disorders typically does: o Family (or pedigree) studies, twin studies, and adoption studies - When problem that characterizes the index case also occurs in the comparison person, the two are said to be concordant (or to display concordance for the problem) - Most recent techniques for studying genetic influences include genetic linkage studies and research methods in molecular biology - In genetic linkage studies, researchers examine families that have a high incidence of a particular psychiatric disorder o Researchers looks for the presence of particular traits (genetic markers) that can be linked to the occurrence of the disorder o If all members of the family who have the mental disorder also have the genetic marker, but the unaffected family members do not, then the conclusion is that the mental disorder has a genetic origin - Researchers in molecular biology have been able to compare specific DNA segments and identify the genes that determine individual characteristics o These methods underlie the attempt to map the entire human genome, and researchers have been able to pinpoint the defective genes that cause various medical and psychological disorders Psychosocial Theories - Psychodynamic theorists, like Freud, have suggested that behaviour is motivated by unconscious processes acquired during the formative years of life - Humanists and existentialists suggest that personal experience provides the basis for the development of self-directed behaviour - Socio-cultural theorists suggest that the surrounding society or culture exerts powerful influences on people Psychodynamic Theories - Psychodynamic theories claim that behaviour is controlled by unconscious forces of which the person is unaware - Consider the origins of unconscious controls to reside in the individual’s personal experience - Levels of Consciousness o Conscious, which contains information of which we are currently aware o Preconscious, which holds information not presently within our awareness but that can readily be brought into awareness o Unconscious, which according to Freud, contains the majority of our memories and drives that, unfortunately, can only be raised to awareness with great difficulty and typically only in response to particular techniques o Freud thought that sexual and aggressive drives resided in the unconscious, which he considered to be instinctual, upset people so much that they could not face the fact they had such urges. These unacceptable drives and the traumatic memories were kept out of awareness by what Freud called defence mechanisms. - Structures of Personality o Id is the structure present at birth and contains biological or instinctual drives for instant gratification without concern of consequences – pleasure principle o Ego develops in the first year of life to curb the desires of the id so that the individual does not suffer any unpleasant consequences. As the individual learns what expressions of desires are practical and possible, the ego comes to e governed by the reality principle. Notes From Reading CHAPTER  2: HEORETICAL  PERSPECTIVES ON ABNORMAL  BEHAVIOUR  PGS. 23
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