1. Psychology: Brain, Mind, and Culture, 2e by Drew Westen
Paul J. Wellman
Texas A&M University
John Wiley and Sons, Inc.
PowerPoint  Presentation: Chapter 2
Psychology: Research Methods in Psychology

2. © 1999 John Wiley and Sons, Inc.
Lecture Outline
Characteristics of Good Psychological Research
Experimental Research
Descriptive Research
Correlational Research
Researching the Brain
Descriptive Statistics
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3. © 1999 John Wiley and Sons, Inc.
Research Methods
“Can mental events influence physical health?”
Pennebaker study (1990)
College students were asked to write for 20 min on 3 consecutive days on two topics:
Emotional expression: “…your deepest thoughts”
Control group: “what have you done since waking this morning?”
Pennebaker then measured visits to the campus health center for subjects in both groups for months after the writing exercises
Results indicate that emotional expression subjects made fewer visits to the health center
Yes, emotional expression can improve health...
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4. Characteristics of Good Psychological Research
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5. © 1999 John Wiley and Sons, Inc.
Research Concepts
Psychologists are interested in determining the causes of mental events and behaviors
“What is the impact (effect) of divorce on children?”
Issues in Theory:
Systematic way of organizing observations
Hypotheses are proposed relations between variables (cause-effect relationships)
Variable: Any phenomenon that can vary along some dimension
Continuous: varies continuously (body weight)
Categorical: can take on fixed values (gender)
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6. Generalizability of Research
Research studies take samples from a limited portion of the entire population (sampling must be representative).
Generalizability refers to whether your research results can be applied to the entire population of interest, and requires:
Internal validity: Are the procedures of the study sound or are they flawed?
External validity: Does the experimental situation resemble the situation found in the real world?
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7. Measurement Issues in Research
Measure: A concrete means by which to determine the value of a variable
The variable “illness” can be defined as the number of times that a subject visits a clinic
The variable “hunger” can be defined in terms of how long a subject has gone without food
Measures of variables must be:
Reliable: Produce consistent measurements
Valid: Actually measure the variable of interest
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8. Three Techniques to Determine the Reliability of a Measure
Test-retest reliability: Does the test give similar values if the same subject takes it two or more times?
Internal consistency: Different items that measure the same variable should produce similar answers.
Inter-rater reliability: Two testers that rate the same person on the same variable should give similar ratings to the subject
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Issues in Validity
Do the measures tap the appropriate variable?
Valid measures should allow for prediction of behavior
Measure of depression: Does it predict risk for suicide in the future?
Measure of intellect (IQ): Does it predict future school performance?
Validation research attempts to relate the measure to an objective criterion
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10. The Experimental Research Process
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Defining Experiments
Experiments ask whether systematic variation in one variable produces variation in another variable
Independent variable (IV): Manipulated by experimenter
Dependent variable (DV): Participants response
Example: Does exposure to THC increase appetite?
IV: THC dose (0 or 5 mg)
DV: Amount of food consumed in 30 minutes
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12. Issues in Experimental Research
Control groups: A group that is similar to the experimental group, except that it has not been exposed to the treatment (i.e given a placebo treatment rather than THC)
Bias: Variation associated with subject expectancies, experimenter expectancies
Placebo treatments
Double-blind studies
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13. Limitations of Experimental Research
Complex real-world issues may not be easily studied in the laboratory
Problems in external validity
The focus of experimental psychology is off-base: The interpretative stance suggests that we should strive to understand the personal meanings that govern behavior rather than focus on predicting behavior
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Descriptive Research
The descriptive approach seeks to describe phenomena rather than to manipulate variables
Methods of descriptive research:
Case studies
Naturalistic observation
Survey research
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Case Studies
An in-depth study of the behavior of one person or a small group
Used when large numbers of subjects are not available
Often used in clinical research
Freud’s case study approach
Drawbacks include
Small sample size (limit to generalizability)
Susceptibility to researcher bias
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16. Naturalistic Observation
In-depth study of a phenomenon in its natural setting
Examples include:
Study of primate behavior in the wild
Piaget’s study of the cognitive development of his own children
Advantage: Naturalistic studies have good generalizability
Disadvantages:
Observation per se can alter behavior
Observational technique cannot infer cause of behavior
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17. © 1999 John Wiley and Sons, Inc.
Survey Research
Survey technique asks questions of large numbers of persons to gain information on attitudes and behavior
Two approaches:
Questionnaires
Interviews
Disadvantages of survey approach:
Sampling issues
People may not respond accurately
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18. Correlational Research
Aim of the correlational approach is to determine the degree to which 2 or more variables are related
Can determine association between data from experiments, case studies, or surveys
Calculate the correlation coefficient (r)
Values range from -1 through 0 through +1
Negative correlations: High values of one variable are associated with low values of the other variable
Correlational studies do NOT establish causality
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19. The Correlation Coefficient
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20. Researching the Brain (Then)
Research progress is dependent on the technology available to investigators
Early brain-behavior researchers were able to examine the thoughts and behaviors of patients who had suffered brain damage
Broca noted that left hemisphere damage produced a disorder of language
Lesion experiments in animals: Create a lesion within a discrete brain region and then examine the effects of that lesion on behavior
Hypothalamic damage can lead to obesity or starvation, depending on the location of damage
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21. Researching the Brain (Now)
Brain imaging techniques allow us to look for brain damage or to assess the activity of discrete brain regions
CAT and MRI scans produce a static picture of brain structures
MRI can be used to detect tumors
Brain ventricle size: Large ventricles are associated with brain damage
PET scans: Radioactive tracers are used to map brain regions for high and low activity
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22. Brain Imaging: Ventricle Size in Schizophrenia
Normal
Schizophrenic
Schizophrenic twin on right shows larger brain ventricles
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23. Issues in Evaluating Research
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24. Descriptive Statistics
Measurements of subject responses on a variable are summarized using descriptive statistics:
Frequency distribution of responses
Histogram plots score range along x axis and score frequency along y axis
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25. Central Tendency and Variability
Central tendency asks what the average score is like in the distribution of scores
Mean: Statistical average of all scores
Median: The fiftieth percentile (half of the scores are above this score, half are below)
Mode: The most frequent score
Variability asks how dispersed the scores are relative to the average score
Standard deviation: How far the average participant score deviates from the average
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26. The Normal Distribution
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27. © 1999 John Wiley and Sons, Inc.
Copyright
Copyright 1999 by John Wiley and Sons, New York, NY. All rights reserved. No part of the material protected by this copyright may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission of the copyright owner.
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