Unformatted text preview: The Science of Psychology
G & H Chapter 2 Is Psychology just common sense? Sometimes wrong/slippery Postdictions vs. Predictions 1 Common Sense...? Hindsight Bias Overconfidence False Consensus Effect The "not me" effect Illusory Correlation Anecdotal Evidence Thinking Critically Thinking that does not blindly accept arguments and conclusions examines assumptions discerns hidden values evaluates evidence assesses conclusions Critical thinking is not easy, it takes practice. The Scientific Attitude = "Curious skepticism" skepticism" We want to know the how and why of things, but... but... How do you know? "show me the evidence" evidence" Maintain an open mind, but with a healthy dose of skepticism. 2 An Approach to Critical Thinking... By Dr. Brian C. Nolan Don't accept things a face value. Don' When confronted with a new idea...FIRST ask, what is idea... wrong with it? Where are the holes? What are they not telling me? Once you've found a hole... you' hole... How big is it? Is it a significant hole? Should you reject the idea idea because of this hole? Is it a minor nit-picky point? If it's a minor hole, maybe it's not a nitit' it' big deal. What are the strengths? Does it have any redeeming value? If you can't find a hole... can' hole... Did you look hard enough? If you've looked hard and still can't find any holes...then MAYBE you' can' holes... it is a solid idea. The Scientific Method Observation Hypothesize Test Evidence Theory: (attempts to) unifies the known facts New Observation New Evidence Modify / update / change theory Dynamic Process never finished, never 100% 3 What's wrong with this picture? The nature of Scientific Truth... Truth... 4 A Good Theory
1. Fits known facts 2. Falsifiable 3. Testable 4. Parsimonious 5. Predictive Value Methods in Psychology
I. Descriptive Techniques
A. Case Studies e. g. Phineas Gage Usefulness? Generalizable? Generalizable? 5 Observation
B. Natural Observation Surveys...
C. Survey Not an experiment Likert scales and semantic scales 6 Surveys... Problems with Surveys: Problems in wording How bad does asparagus taste? How does asparagus taste? Likert scale order Response set... set... Problems with self-report!!! self- Correlational Studies...
a. b. Correlational Studies
Relationship between 2 things Types: + , - , 0 7 Correlational Studies... Correlation Coefficient
Indicates direction of relationship (positive or negative) Correlation coefficient r = +.37 Indicates strength of relationship (0.00 to 1.00) 8 Correlational Studies...
d. Pearson's r Correlation coefficient +1.0 to -1.0 0 0.19 Low 0.20 0.49 0.50 0.75 0.75 1.00 Moderate Strong Very Strong e. Correlation does not equal Causation! Usefulness? Correlational Studies... Correlational Studies Advantages Natural environment Quantifies strength of relationship Predictive value Disadvantages Directionality problem 3rd variable problem 9 3rd Variable Problem
Three Possible Cause-Effect Relationships
(1) Low self-esteem could cause Depression or
(2) Depression could cause Low self-esteem or
Low self-esteem (3) Distressing events or biological predisposition could cause and Depression Experimentation...
a. b. Determine cause-effect relationship Manipulate variable in controlled situation Experimental Hypothesis Hypothesized Cause Hypothesized Effect Examples... Examples... Jogging daily will cause changes in a person. Jogging daily will cause mood changes. Jogging daily will lead to more positive moods. 10 Experimentation... Independent Variable (jogging daily...) daily... Dependent Variable (mood...) (mood... Random Assignment / Standardized Treatment Bias Demand Characteristics: cues about expectations Subjects will tend to give experiments what they expect Experimentation... Placebo effect Double blind procedure Reproducibility of results 11 Experimentation... In order to make a statement about causeeffect relationship, must have... Standardized treatment (NO DIFFERNCES) Except 1 factor (independent variable) Therefore any change must be because of independent variable This is what makes it an experiment! Experimentation... Limits of experimental method Ethical issues? Random assignment not always possible Demographic variables can't be changed 12 Video: Understanding Research Methods... Experiment vs. Correlation In correlation No random assignment No manipulation of variables No causal conclusions But, get at information you can't by experimentation can' Examples of Exp. Vs. Corr. Corr. 13 Methods... Ruler Demo. 14 Statistical Reasoning Describing Data Organizing Presenting data Beware of subtle manipulations in presentation of data Data Measures Central Tendency Mean Median Mode 15 Central Tendency Data Measures... Variability Range Standard Deviation Statistical Significance The Law of Large Numbers 16 Samples and Randomness Representative Samples Random Samples Samples and Randomness... What is the chance of flipping "heads" On the 1st flip? After 5 "tails" in a row? After 10 "tails" in a row? Which is more likely... HHHTTT or HTTHTH or HHHHHH The illusion of "hot streaks" 17 ...
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- Spring '08
- Psychology, Correlational Studies