1. Understanding Psychology
Chapter 2:
Scientific Methods
Change picture of book!!!
This multimedia product and its contents are protected under copyright law. The following are prohibited by law:
Any public performance or display, including transmission of any image over a network;
Preparation of any derivative work, including the extraction, in whole or in part, of any images;
Any rental, lease, or lending of the program
Slide author:
Larry D. Thomas, Ph.D. Blinn College
Copyright 2007 Horizon Textbook Publishing

2. Scientific Methods

3. Psychology Psychology Scientific method
The scientific study of behavior and mental processes
Scientific method
The orderly, systematic procedures researchers follow as they identify a research problem, design a study to investigate the problem, collect and analyze data, draw conclusions, and communicate their findings 2 2

4. Understanding Probability?
Answers No
50%
Understanding Probability?
Does a basketball player have a better chance of making a shot after having just made his last 2 of 3 shots than he does having just missed his last 2 of 3 shots?
Yes _____ No _____
When shooting free throws, does a player have a better chance of making his second shot after making his first shot than after missing his first shot?
Is it important to pass the ball to someone who has just made several (2,3,or 4) shots in a row?
Consider a hypothetical player who shoots 50 percent from the field. What is your estimate of her field goal percentage for those shots she takes after having just made a shot?
_____ %
What is your estimate of her field goal percentage for those shots that she takes after having ust missed a shot?
Source: Tversky, A., & Gilovich, T. (1989). The cold facts about the “hot hand” in basketball. Chance: New Directions for Statistics and Computing, 2, 2 2

5. Descriptive Research Methods
Two types of research that help psychologists accomplish these goals
Basic research
Research conducted to advance knowledge rather than for its practical application
Example: the nature of memory
Applied research
Research conducted to solve practical problems
Example: methods to improve memory
Note: Replication is important in all research because it reduces the chances of the finding being by chance and expands the research to be generalized to broader populations. 2 2

6. Descriptive Research Methods
Research methods that yield descriptions of behavior rather than causal explanations 2 2

7. Descriptive Research Methods
Case study
An in-depth study of one or a few individuals consisting of information gathered through observation, interview, and perhaps psychological testing
Disadvantages
Lack of investigative control
Potential for subjective bias by researcher
Poor sampling techniques limit generalization
Tendency for subjects to report inaccurately 2 2

8. Descriptive Research Methods
Survey
A method in which researchers use interviews and/or questionnaires to gather information about the attitudes, beliefs, experiences, or behaviors of a group of people
Good luck is provided when you break the wishbone and get:
The longer piece
The shorter piece
Pieces of equal length
What is a wishbone? 2 2

9. Descriptive Research Methods
Survey Limitations
Demographic bias
Sex bias
Improperly worded questions
Tendency to provide only limited insights about contributing factors to behaviors and attitudes of specific individuals 2 2

10. Descriptive Research Methods
Interviews
Survey results can be affected by the questions’ wording and context
The truthfulness of the responses can be affected by characteristics of the interviewers
Questionnaires
Completed more quickly and less expensively than interviews 2 2

11. Descriptive Research Methods
Naturalistic observation
A research method in which the researcher observes and records behavior in its natural setting, without attempting to influence or control it
Click on black box to play movie. 2 2

12. Descriptive Research Methods
Laboratory Observation
A research method in which behavior is studied in a laboratory setting, where researchers can exert more control and take more precise measurements 2 2

13. Descriptive Research Methods
Observation
Advantages
Gives the opportunity to study behavior in normal settings
Disadvantages
Observer Effect
Subjects behavior may be altered by presence of observer
Must wait for events to occur – time consuming
Cannot reach conclusions about cause-and-effect relationships
Observer bias - A distortion in researchers’ observations that causes them to read too much into the observations or to see only what they expect to see. 2 2

14. Descriptive Research Methods
Population
The entire group that is of interest to researchers and to which they wish to generalize their findings; the group from which a sample is selected
Sample
The portion of any population that is selected for study and from which generalizations are made about the larger population 2 2

15. Descriptive Research Methods
Representative sample
A sample of participants selected from the larger population in such a way that important subgroups within the population are included in the sample in the same proportions as they are found in the larger population
Biased sample
A sample that does not adequately reflect the larger population
Random sample
A sample selected in which each participant has an equal likelihood of selection 2 2

16. Correlational Method Correlational method
A research method used to establish the degree of relationship (correlation) between two characteristics, events, or behaviors
For use when it is impossible to manipulate variables of interest
There are many variables of interest to psychologists that cannot be manipulated
Can be done more quickly and cheaply than experiments 2 2

17. Correlational Method Correlational coefficient
A numerical value that indicates the strength and direction of the relationship between two variables; ranges from (a perfect positive correlation) to –1.00 (a perfect negative correlation) 2 2

18. Correlation - Research Method
Correlation Method
Strength of a relationship between two variables
Correlations range from -1 to +1
Correlations are stronger the further they are from zero
Zero means no correlation (relationship) between the variables was demonstrated
Direction of a relationship between two variables
(+) sign means the variables are related in the same direction.
As one variable increases the other must also increase.
(-) sign means the variables are related in the opposite direction.
As one variable increases the other must decrease.
Limitation
Does not demonstrate Cause and Effect

19. Experimental Method Experimental method
The research method in which researchers randomly assign participants to groups and control all conditions other than one or more independent variables, which are then manipulated to determine their effect on some behavioral measure – the dependent variable in the experiment 2 2

20. Experimental Method Hypothesis Variable
A prediction about the relationship between two or more variables
Variable
Any condition or factor that can be manipulated, controlled, or measured 2 2

21. Experimental Method Independent variables Dependent variable
In an experiment, the factor or condition that the researcher manipulates in order to determine its effect on another behavior or condition known as the dependent variable
Sometimes referred to as the treatment
Dependent variable
The variable that is measured at the end of an experiment and is presumed to vary as a result of manipulations of the independent variable 2 2

22. Experimental Method Experimental group Control group
In an experiment, the group that is exposed to the independent variable, or the treatment
Control group
In an experiment, a group that is similar to the experimental group and is exposed to the same experimental environment but is not exposed to the independent variable; used for purposes of comparison 2 2

23. Experimental Method Confounding variables
Any factors or conditions other than the independent variable that could cause observed changes in the dependent variable 2 2

24. Experimental Method Selection Bias Random Assignment
The assignment of participants to experimental or control groups in such a way that systematic differences among the groups are present at the beginning of the experiment
Random Assignment
In an experiment, the assignment of participants to experimental and control groups by using a chance procedure, which guarantees that each has an equal probability of being placed in any of the groups, a control for selection bias 2 2

25. Experimental Method The Placebo Effect Placebo
The phenomenon that occurs when a person’s response to a treatment or response on the dependent variable in an experiment is due to expectations regarding the treatment rather than to the treatment itself
Placebo
Some inert substance, such as a sugar pill or an injection of saline solution, given to the control group in an experiment as a control for the placebo effect 2 2

26. Experimental Method Experimenter bias
A phenomenon that occurs when the researcher’s preconceived notions in some way influence the participants’ behavior and/or the interpretation of experimental results
A researcher’s expectations can be communicated to participants, perhaps unintentionally, through tone of voice, gestures, or facial expression
Double-blind technique
An experimental procedure in which neither the participants nor the experimenter knows who is in the experimental or control groups until after the results have been gathered; a control for experimenter bias 2 2

27. Experimental Method Limitations of the Experimental Method
The more control a researcher exercises over the setting, the more unnatural and contrived the research setting becomes
Unethical or not possible in many areas of interest
Insert a picture of a man climbing a mountain 2 2

28. Participants in Psychological Research
Protecting Research Participants’ Rights
The main provisions of the code:
Legality
Conforms to applicable federal, state, and local laws and regulations
Institutional approval
Obtain approval from all institutions involved in a study
Informed consent
Participants must be informed of the purpose of the study and its potential for harming them
Deception
Is ethical when it is necessary 2 2

29. Participants in Psychological Research
Protecting Research Participants’ Rights
The main provisions of the code (continued):
Debriefing
When participants are deceived the researcher must tell participants about the deception as soon as the study is complete
Clients, patients, students,and subordinates
Researchers must take steps to ensure that participation in a study, and the information obtained during participation, will not damage the subordinates in any way 2 2

30. Participants in Psychological Research
Protecting Research Participants’ Rights
The main provisions of the code (continued):
Publication
Report findings in an appropriate forum 2 2

31. Participants in Psychological Research
Important guidelines for using animals in psychological research:
Legality
Must continued all relevant federal, state and local laws
Supervision by experienced personnel
Must be supervised by the people who are trained in the animal’s care
Minimization of discomfort
Researchers are ethically bound to minimize any discomfort to research animals 2 2

32. Statistical Concepts for Research
Statistics - Mathematical methods for describing and interpreting data.
Descriptive Statistics
Mathematical and graphical methods for reducing data to a form that can be readily understood
Inferential Statistics
Process of using mathematical procedures to draw conclusions about the meaning of data 2 2

33. Statistical Concepts for Research
Measures of Central Tendency
Mean
Arithmetic average
Sum of scores divided by the number of scores
Median
50th percentile
Middle of distribution when arranged in order
Mode
Most frequent score 2 2

34. Statistical Concepts for Research
Measures of Variability
Range
Difference between the highest score and the lowest score
Standard Deviation
The average extent to which all scores in the distribution vary from the mean
Variance
Square root of the Standard Deviation 2 2

35. Statistical Concepts for Research
Measures of Variability
Operational Definition
Definition specifying the operations that are used to measure or observe a variable
Such as a definition of obesity specifying a certain weight-height relationship.
Statistical Significance
The degree to which the changes in the dependent variable can be attributed with a high level of confidence to the experimental condition (independent variable) be manipulated by the researcher. 2 2