© Cengage Learning 2016 © Cengage Learning 2016 Research Methods for Studying Mental Disorders 4
© Cengage Learning 2016 © Cengage Learning 2016
Research Methods for Studying Mental Disorders
4
© Cengage Learning 2016
• Scientific method– Systematic data collection, controlled
observation, and testing hypotheses
• Hypothesis – Tentative explanation for certain facts or
observations
• Theory – Group of principles and hypotheses that
together explain some aspect of a particular area of inquiry
Research Methods Used to Study Mental Disorders
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• Replication– Repeating results under similar test conditions
• Replicating research has resulted in changes to previous “conclusive” results– Examples:
• Childhood vaccines may cause autism
• Antidepressants raise suicide risk in children and adolescents
• Most sexually abused children exhibit signs of trauma
Importance of Replication
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• Development of hypotheses about relationships
• Potential for self-correction
• Consideration for reliability and validity
• Use of operational definitions
• Acknowledgement of base rates
• Evaluation based on statistical significance
Characteristics of Clinical Research
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• Best tool for testing cause-and-effect relationships
• Components of a simple experiment– Experimental hypothesis
– Independent variable• Manipulated by the experimenter
– Dependent variable• Expected to change as a result of manipulating the
independent variable
Experiments
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• Experimental group– Group exposed to an independent variable
• Control group– Similar in every way to experimental group
but not exposed to independent variable
• Placebo group– Participants receive an inactive substance
• Over 75 percent of participants may correctly guess their position in this group based on effects
Types of Groups in an Experiment
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• Design of the experiment– Single-blind design
• Participants unaware of purpose of research
– Double-blind design• Participant and individual working directly with the
participant unaware of the experimental conditions
• Some variables cannot be manipulated– Example: child abuse
– Correlational studies are appropriate
Additional Controls in Experimental Research
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• Statistical analysis to determine correlation between variables
• Allow analysis of variables that cannot or should not be controlled
• Types of correlation– Positive correlation
– Negative correlation
– No correlation
Correlational Studies
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Possible Correlations Between Two Variables
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• Investigation that attempts to simulate real-life situation under controlled conditions
• Used when not possible to control all variables in real-life situations – Or when ethical, legal, or moral issues
preclude other types of studies
Analogue Studies
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• Behaviors and events are observed and recorded in their natural environment
• The main technique is observation– Sometimes with interviews or questionnaires
• Observers must be highly trained– Avoid disrupting the natural environment
• Provides no information about causality
• Difficult to control variables
Field Studies
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• Most studies are nomothetic– Study large numbers of people collectively
• Idiographic study– In-depth study of one person
– Used to examine a rare or unusual phenomenon
• Types of single-participant studies– Case study
– Single-participant experiment
Single-Participant Studies
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• Intensive study of one individual– Relies on clinical data
• Observations
• Medical and psychological tests
• Historical and bibliographic information
• Can determine characteristics, course, and outcome of a rare disorder
• Used to study therapeutic or diagnostic techniques
Case Study
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• Some aspect of a person’s behavior is used as a control (baseline) for comparison with future behaviors
• Multiple-baseline study – Baselines on two or more behaviors or the
same behavior in two or more settings are obtained prior to intervention
• Raises questions about external validity
Single-Participant Experiment
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A Multiple-Baseline Study
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• Methods for studying biological processes involved in mental illness– Endophenotypes
– Twin comparisons
– Genetic studies
– Study of the epigenetic processes
Biological Research Strategies
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• Endophenotypes: measurable characteristics– Characteristic must be heritable
– Occur more frequently in affected families than in the general population
– Examples: anatomical or chemical differences in the brain, eye-tracking irregularities
• Guide prevention and early treatment efforts
The Endophenotype Concept
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• Monozygotic (identical) twins– Share the same DNA
– Have different fingerprints
– Develop more differences from one another as they age
• Fraternal twins– Share same childhood environments
– Often used to evaluate hereditary versus environmental influences on development
Twin Studies
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• Goal: determine whether a disorder follows a genetic pattern
• If disorder is genetically linked:– Individuals closely related to person with
disorder (proband) more likely to display disorder
• Penetrance– Proportion of individuals with a particular
genotype who manifest the phenotype
Genetic Linkage Studies
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• Study of environmental factors that influence whether or not a gene is expressed
• Builds on idea that certain environmental factors have greatest impact during sensitive periods in development
• Epigenetic changes can leave an imprint on eggs or sperm– Affects traits inherited by future generations
Epigenetic Research
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• The use of animal models is a frequent practice– Allows for better control of variables
– Permits experimental procedures not practical to use on humans
– Example: newborn mice separated from mothers resulted in different behavior, emotional development, and gene expression
• Researchers were able to pinpoint the occurrence of exact biological processes
Using Animals in Biological Research
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• Examines rate and distribution of mental disorders in the population
• Prevalence– Percentage of individuals in targeted
population with a particular disorder during a specific period of time
• Incidence– Number of new cases of a disorder that
appear in an identified population within a specific period of time
Epidemiological Research
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• Meta-analysis: simplified process of comparing numerous research findings– Published versus unpublished studies
• Increasing emphasis on evidence-based practice
• Concerted effort to reduce bias and misconduct
• Focus on locating biomarkers and endophenotypes for particular disorders
Contemporary Trends and Future Directions
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• What methods do researchers use to study the causes of and treatments for psychopathology?
• How does biological research help us understand causes of abnormal behavior?
• Why is epidemiological research important in understanding mental illness?
• What are current trends in psychopathology research?
Review