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

© 1999 John Wiley and Sons, Inc. Lecture Outline Characteristics of Good Psychological Research Experimental Research Descriptive Research Correlational Research Researching the Brain Descriptive Statistics © 1999 John Wiley and Sons, Inc.

© 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... © 1999 John Wiley and Sons, Inc.

Characteristics of Good Psychological Research © 1999 John Wiley and Sons, Inc.

© 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) © 1999 John Wiley and Sons, Inc.

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? © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

© 1999 John Wiley and Sons, Inc. 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 © 1999 John Wiley and Sons, Inc.

The Experimental Research Process © 1999 John Wiley and Sons, Inc.

© 1999 John Wiley and Sons, Inc. 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 © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

© 1999 John Wiley and Sons, Inc. Descriptive Research The descriptive approach seeks to describe phenomena rather than to manipulate variables Methods of descriptive research: Case studies Naturalistic observation Survey research © 1999 John Wiley and Sons, Inc.

© 1999 John Wiley and Sons, Inc. 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 © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

© 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 © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

The Correlation Coefficient © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

Brain Imaging: Ventricle Size in Schizophrenia Normal Schizophrenic Schizophrenic twin on right shows larger brain ventricles © 1999 John Wiley and Sons, Inc.

Issues in Evaluating Research © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

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 © 1999 John Wiley and Sons, Inc.

The Normal Distribution © 1999 John Wiley and Sons, Inc.

© 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. © 1999 John Wiley and Sons, Inc.