Chapter 2

1. Chapter 2 The Ways and Means of Psychology Chapter 2 - The Ways and Means of Psychology

2. The Scientific Method The 3 Major Types of Scientific Research are: Naturalistic Observations involve observing people or animals in their natural environment with as little involvement as possible Correlational Studies are often observational, but also involve the measurement and examination of variables that may be related to certain behaviours Finally, experiments use active manipulation to gain a better understanding of how certain variables effect behaviour Chapter 2 - The Ways and Means of Psychology

3. Rules of the Scientific Method 1. Identify the problem and formulate cause-effect hypotheses 2. Design the experiment (PsyB01) 3. Perform the experiment 4. Evaluate the hypothesis on the basis of the obtained data (PsyB07) 5. Communicate the results (PsyC02) Plug for C90 & C93s Chapter 2 - The Ways and Means of Psychology

4. Rules of the Scientific Method 1. Identify the problem and formulate cause-effect hypotheses 2. Design the experiment (PsyB01) 3. Perform the experiment 4. Evaluate the hypothesis on the basis of the obtained data (PsyB07) 5. Communicate the results (PsyC02) Plug for C90 & C93s Chapter 2 - The Ways and Means of Psychology

5. Examples Steve shows you his “vacation video” of a shark dive as a way of illustrating the continuous nature of naturalistic observations Via the “chainmail” suit, explains how naturalistic observations can lead the formation of a hypothesis Follows this up with the “shark electrical experiment video” to show how an experiment can then be done to test the hypothesis Chapter 2 - The Ways and Means of Psychology

6. Rules of the Scientific Method 1. Identify the problem and formulate cause-effect hypotheses 2. Design the experiment (PsyB01) 3. Perform the experiment 4. Evaluate the hypothesis on the basis of the obtained data (PsyB07) 5. Communicate the results (PsyC02) Plug for C90 & C93s Chapter 2 - The Ways and Means of Psychology

7. Designing an Experiment Some Basic Terminology (in sharky context) Variable - Anything that can take on multiple values Independent Variable - A variable that is manipulated by the experimenter (presence or absence of an electric field) Dependent Variable - A variable that is measured during an experiment … typically an index of behaviour (some measure of avoidance behaviour) Chapter 2 - The Ways and Means of Psychology

8. Designing an Experiment Often experiments involve a contrast between the behaviour of subjects in a control condition (a group or condition in which the critical manipulation is not present) with an experimental group (a group or condition where the critical manipulation is present) For example, the experimental condition of the shark study was when the electric field was on, the control condition was when it was off Chapter 2 - The Ways and Means of Psychology

9. Operational Definitions Often our theory involves general ideas, but experiments require specific variables … thus we must define our concepts operationally, in terms of some variables that can be measured or manipulated e.g., students who are encouraged to actively participate in classes will learn better Chapter 2 - The Ways and Means of Psychology

10. Operational Definitions Often our theory involves general ideas, but experiments require specific variables … thus we must define our concepts operationally, in terms of some variables that can be measured or manipulated e.g., students who are encouraged to actively participate in classes will learn better Making course notes available? Verbally encouraging students to participate? Chapter 2 - The Ways and Means of Psychology

11. Operational Definitions Often our theory involves general ideas, but experiments require specific variables … thus we must define our concepts operationally, in terms of some variables that can be measured or manipulated e.g., students who are encouraged to actively participate in classes will learn better Final marks? Student evaluations of learning? Chapter 2 - The Ways and Means of Psychology

12. Validity of an Experiment The validity of an experiment refers to how well the operational definitions capture the concept of interest Manipulation checks can be used to test the validity of independent variables The validity of an experiment is also strengthened if other operational definitions of the same concept(s) provide similar results (i.e., converging evidence) Chapter 2 - The Ways and Means of Psychology

13. Confound it! In order to attribute the results of the experiment to the independent variable that was manipulated, it is important that the critical conditions were systematically different only in terms of that variable If some other variable also differed across conditions, then the two variables are said to be confounded, and it is impossible to attribute the results to either variable in a convincing manner e.g. - can you tell me how to get to Sesame Street? Chapter 2 - The Ways and Means of Psychology

14. Counterbalancing to Avoid Confounds Sometimes it is necessary to use counterbalancing techniques to avoid confounds For example, the Stroop example we did last class actually included a confound … practice (subjects usually get faster at any task with practice on that task) Solution … half the subjects get the congruent list followed by the incongruent … and half get the incongruent followed by the congruent Chapter 2 - The Ways and Means of Psychology

15. Rules of the Scientific Method 1. Identify the problem and formulate cause-effect hypotheses 2. Design the experiment (PsyB01) 3. Perform the experiment 4. Evaluate the hypothesis on the basis of the obtained data (PsyB07) 5. Communicate the results (PsyC02) Plug for C90 & C93s Chapter 2 - The Ways and Means of Psychology

16. Reliability If you measure your height over and over, you’ll tend to get the same height each time … rulers are reliable What if you wrote the “same” test over and over, would you expect to always get the same mark? And what if the conditions of testing changes with each test? It is important that variables be measured as reliably as possible when an experiment is performed … the more reliable a variable can be measured, the higher the chance of finding a difference/relation if it exists Chapter 2 - The Ways and Means of Psychology

17. Subjective Measures and Inter-rater Reliability Some variables can be measured objectively (e.g., reaction times), others are more subjective (e.g., babies reactions) It is harder to reliably measure a subjective variable, and often one must use multiple raters and examine inter-rater reliability to insure reliability of measurement This is done by seeing how often independent raters agree in their measures … low agreement = poor reliability Chapter 2 - The Ways and Means of Psychology

18. Reliability versus Validity Note the difference between reliability and validity Reliability is the likelihood of getting the same result if some variable is measured on multiple occasions Validity refers to how well some variable reflects some psychological concept e.g., IQ tests of Intelligence Chapter 2 - The Ways and Means of Psychology

19. The Importance of Random Assignment Often independent variables are confounded because of subject differences across the groups The best way to avoid subject differences is to use random assignment If random assignment is combined with fairly large sample sizes, the groups should not be systematically different in terms of the variables you know to be relevant AND the ones you don’t know about Chapter 2 - The Ways and Means of Psychology

20. Those Pesky Subjects! Subjects hardly ever just go along with an experiment … rather, they never trust the experimenter, and almost always believe there is more to the experiment than the experimenter lets on (sometimes they are right!) As a result, they do not behave “naturally”, but instead they try to figure the study out, and their behaviour is partially a function of their hypotheses about the exp An experiment must do all that is possible to avoid such expectations to bias the results of their study Chapter 2 - The Ways and Means of Psychology

21. Single Blind Studies One way to try preventing a subject’s expectations from “causing an effect” is to not allow the subject to figure out what condition of an experiment they are in: e.g., subliminal perception “weight loss” tapes … placebo idea Thus, subjects in both the experimental and control groups might expect something, but there is no reason to believe that expectations would be different across the conditions … food is crap ... Chapter 2 - The Ways and Means of Psychology

22. Double-Blind Experiments Sometimes it is not enough to have just the subject “blind” to what condition they are in, as it is possible that the experimenter might react differently to subjects depending on which condition they are in In those cases it is sometimes optimal to have the experimenter “blind” as well throughout the course of the experiment I have no idea! Where am I? Chapter 2 - The Ways and Means of Psychology

23. A Question of Ethics - Human > Subjects cannot be coerced into participating in experiments (hence course credit in A01) > Subjects must be told the ethically relevant aspects of the experiment, then give their informed consent Deception is justified, as long as: > participant is debriefed after the study > does not otherwise harm the subject either psychologically or physically > the dignity of the subject is maintained Confidentiality of data is also necessary Chapter 2 - The Ways and Means of Psychology

24. A Question of Ethics - Non-Human Animals must be treated “humanely” in research settings > no unnecessary suffering > approved procedures for surgery and the like Animal research should only be conducted if it is worthwhile > what is worthwhile? > the trend towards “simulated” rats Issue of the treatment of pets versus research animals Chapter 2 - The Ways and Means of Psychology

25. Rules of the Scientific Method 1. Identify the problem and formulate cause-effect hypotheses 2. Design the experiment (PsyB01) 3. Perform the experiment 4. Evaluate the hypothesis on the basis of the obtained data (PsyB07) 5. Communicate the results (PsyC02) Plug for C90 & C93s Chapter 2 - The Ways and Means of Psychology

26. Statistics In my statistics class (PsyB07) I give the students a questionnaire on the first day, and use the data from this questionnaire throughout the class to demonstrate concepts One of the things I ask them is how old they are. Here are some data 21, 20, 23, 21, 23, 22, 20, 21, 22, 22, 21, 25, 19, 22, 21, 23, 26, 24 OK, now what? Chapter 2 - The Ways and Means of Psychology

27. Descriptive Statistics Usually the first step to analyzing the data is to describe the data by boiling down to certain descriptors (describe someone) The usual suspects: Frequency Tables and Histograms Measures of Central Tendency - Mean, Median, Mode Measures of Variability - M.A.D. and Variance Sometimes when we measure more than one variable, we want to know something else too: Are the variables related? Scatterplots, correlations Chapter 2 - The Ways and Means of Psychology

28. Frequency Tables and Histograms Frequency Tables and Histograms all you to depict all the data in a fairly concise way Age Frequency 19 1 20 2 21 5 22 4 23 3 24 1 25 1 26 1 Chapter 2 - The Ways and Means of Psychology

29. Measures of Central Tendency Sometimes we want to communicate the data in an even briefer form … one characteristic we often choose to communicate is some measure of “middle” to show a representative point Mean - The point that is the minimum possible distance from all the other points in the sample Median - The point that have the data points lie above, and half lie below Mode - The most frequently occurring data point (or observation) Chapter 2 - The Ways and Means of Psychology

30. Measures of Variability Another characteristic we often which to quantify is the extent to which our data points lie close to the middle point e.g., 18, 19, 20, 21, 22 vs. 5, 12, 20, 28, 35 M.A.D. - The mean absolute deviation of each data point from the mean of the numbers Variance - The average squared deviation of each data point from the mean Chapter 2 - The Ways and Means of Psychology

31. Inferential Statistics Quite often our end goal is not merely to measure some variable but, rather, we wish to compare different groups to see if they differ in terms of some variable The tests we do to look for differences fall under the heading termed “inferential statistics” and include such things as t-tests, z-tests, analysis of variance, and correlations These are statistical procedures we use to eventually make inferences about how some variable affects the behaviour of our population of interest Chapter 2 - The Ways and Means of Psychology

32. A Taste of Statistical Logic Observed Difference > If large, we have an effect > If not, we don’t Difference That Would be Expected by Chance Chapter 2 - The Ways and Means of Psychology

33. A Taste of Statistical Logic Difference between mean height of 6 males vs. 6 females Observed Difference > If large, we have an effect > If not, we don’t Difference That Would be Expected by Chance Chapter 2 - The Ways and Means of Psychology

34. A Taste of Statistical Logic Difference between mean height of 6 males vs. 6 females Observed Difference > If large, we have an effect > If not, we don’t Difference That Would be Expected by Chance Average difference between mean height of 6 randomly selected people, and 6 other randomly selected people Chapter 2 - The Ways and Means of Psychology

35. Rules of the Scientific Method 1. Identify the problem and formulate cause-effect hypotheses 2. Design the experiment (PsyB01) 3. Perform the experiment 4. Evaluate the hypothesis on the basis of the obtained data (PsyB07) 5. Communicate the results (PsyC02) Plug for C90 & C93s Chapter 2 - The Ways and Means of Psychology

36. Communicating the Results Publications - APA formatted manuscripts - The peer-review process - lag Conference Presentations - Typical Format Invited Talks Chapter 2 - The Ways and Means of Psychology