understanding psychology chapter 2: scientific methods this multimedia product and its contents are...

Understanding Psychology

Chapter 2:

Scientific Methods

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Slide author:

Larry D. Thomas, Ph.D. Blinn College

Copyright 2007 Horizon Textbook Publishing

Scientific Methods

Psychology

Psychology– 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

Understanding Probability?

1. 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 _____2. 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?

Yes _____ No _____3. Is it important to pass the ball to someone who has just made

several (2,3,or 4) shots in a row?Yes _____ No _____

4. 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?_____ %

5. 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, 16-21.

Answers

1. No

2. No

3. No

4. 50%

5. 50%

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.


Descriptive research methods– Research methods that yield descriptions of

behavior rather than causal explanations


Case study– An in-depth study of one or a few individuals

consisting of information gathered through observation, interview, and perhaps psychological testing

– DisadvantagesLack of investigative controlPotential for subjective bias by researcherPoor sampling techniques limit generalizationTendency for subjects to report inaccurately


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

1. Good luck is provided when you break the wishbone and get:

A. The longer piece

B. The shorter piece

C. Pieces of equal length

D. What is a wishbone?


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


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


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.


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


Observation– Advantages

Gives the opportunity to study behavior in normal settings

– DisadvantagesObserver Effect

– Subjects behavior may be altered by presence of observer

Must wait for events to occur – time consumingCannot reach conclusions about cause-and-effect

relationshipsObserver 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.


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


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 sampleA sample that does not adequately reflect the larger

population

– Random sampleA sample selected in which each participant has an equal

likelihood of selection

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

Correlational Method

Correlational coefficient– A numerical value that indicates the strength and

direction of the relationship between two variables; ranges from +1.00 (a perfect positive correlation) to –1.00 (a perfect negative correlation)

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.

– LimitationDoes not demonstrate Cause and Effect

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

Experimental Method

Hypothesis– A prediction about the relationship between two or

more variables

Variable– Any condition or factor that can be manipulated,

controlled, or measured

Experimental Method

Independent variables– 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

Experimental Method

Experimental 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

Experimental Method

Confounding variables– Any factors or conditions other than the independent

variable that could cause observed changes in the dependent variable

Experimental Method

Selection Bias– 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

Experimental Method

The Placebo Effect– 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

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 techniqueAn 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

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

Participants in Psychological Research

Protecting Research Participants’ Rights– The main provisions of the code:

Legality– Conforms to applicable federal, state, and local laws

and regulationsInstitutional approval

– Obtain approval from all institutions involved in a studyInformed consent

– Participants must be informed of the purpose of the study and its potential for harming them

Deception– Is ethical when it is necessary


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


Protecting Research Participants’ Rights – The main provisions of the code (continued):

Publication– Report findings in an appropriate forum


Important guidelines for using animals in psychological research:– Legality

Must continued all relevant federal, state and local laws

– Supervision by experienced personnelMust be supervised by the people who are trained in the

animal’s care

– Minimization of discomfortResearchers are ethically bound to minimize any

discomfort to research animals

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 StatisticsProcess of using mathematical procedures to

draw conclusions about the meaning of data


Measures of Central Tendency– Mean

Arithmetic averageSum of scores divided by the number of scores

– Median50th percentileMiddle of distribution when arranged in order

– ModeMost frequent score


Measures of Variability– Range

Difference between the highest score and the lowest score

– Standard DeviationThe average extent to which all scores in the

distribution vary from the mean

– VarianceSquare root of the Standard Deviation


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 SignificanceThe 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.

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