Chapter 5 - Experimental Research

Question 1

2 fundamentals of experiments

Answer 1

Experiments have two fundamental features. The first is that the researchers manipulate, or systematically vary, the level of the independent variable. The different levels of the independent variable are called conditions.

The second fundamental feature of an experiment is that the researcher exerts control over, or minimizes the variability in, variables other than the independent and dependent variable. These other variables are called extraneous variables.

Question 2

Manipulate

Answer 2

Changing the level, or condition, of the independent variable systematically so that different groups of participants are exposed to different levels of that variable, or the same group of participants is exposed to different levels at different times.

Question 3

Single factor two-level design

Answer 3

Independent variables can be manipulated to create two conditions and experiments involving a single independent variable with two conditions are often referred to as a single factor two-level design.

Question 4

Single factor multi-level design

Answer 4

sometimes greater insights can be gained by adding more conditions to an experiment. When an experiment has one independent variable that is manipulated to produce more than two conditions it is referred to as a single factor multi level design.

Question 5

Extraneous variables

Answer 5

an extraneous variable is anything that varies in the context of a study other than the independent and dependent variables.

Question 6

One way to control extraneous variables is to hold them _____.

Answer 6

Constant

Question 7

Two effects of extraneous variables

Answer 7

Extraneous variables make it difficult to detect the effect of the independent variable in two ways. One is by adding variability or “noise” to the data.

The second way that extraneous variables can make it difficult to detect the effect of the independent variable is by becoming confounding variables. A confounding variable is an extraneous variable that differs on average across levels of the independent variable (i.e., it is an extraneous variable that varies systematically with the independent variable).

To confound means to confuse, and this effect is exactly why confounding variables are undesirable. Because they differ systematically across conditions—just like the independent variable—they provide an alternative explanation for any observed difference in the dependent variable.

Question 8

2 more ways to control for confounding variables

Answer 8

1. Hold them constant
2. Randomly assign participants to different conditions.

Question 9

Randomized clinical trial

Answer 9

An experiment that researches the effectiveness of psychotherapies and medical treatments.

Question 10

How to control for placebo effects

Answer 10

1. Put participants in a placebo control condition.
2. Put participants in a waitlist control condition
3. Leave out control condition and compare any new treatment with the best available alternative treatment.

Question 11

4 types of validity

Answer 11

Researchers have focused on four validities to help assess whether an experiment is sound (Judd & Kenny, 1981; Morling, 2014)[1][2]: internal validity, external validity, construct validity, and statistical validity.

Question 12

Internal validity

Answer 12

An empirical study is said to be high ininternalvalidityif the way it was conducted supports the conclusion that the independent variable caused any observed differences in the dependent variable.

Question 13

external validity and mundane realism

Answer 13

An empirical study is high inexternalvalidityif the way it was conducted supports generalizing the results to people and situations beyond those actually studied. As a general rule, studies are higher in external validity when the participants and the situation studied are similar to those that the researchers want to generalize to and participants encounter every day, often described asmundane realism.

Question 14

Psychological realism

Answer 14

Where the same mental process is used in both the laboratory and in the real world.

Answer 15

One of the “big four” validities, whereby the research question is clearly operationalized by the study’s methods.
In addition to the generalizability of the results of an experiment, another element to scrutinize in a study is the quality of the experiment’s manipulations or theconstruct validity.
This conversion from research question to experiment design is calledoperationalization

Question 16

Statistical Validity

Answer 16

Statistical validityconcerns the proper statistical treatment of data and the soundness of the researchers’ statistical conclusions.

The statistical validity speaks to whether the statistics conducted in the study are sound and support the conclusions that are made.

Question 17

Keep this in mind about prioritizing validities:

Answer 17

se four big validities–internal, external, construct, and statistical–are useful to keep in mind when both reading about other experiments and designing your own. However, researchers must prioritize and often it is not possible to have high validity in all four areas. In Cialdini’s study on towel usage in hotels, the external validity was high but the statistical validity was more modest. This discrepancy does not invalidate the study but it shows where there may be room for improvement for future follow-up studies (Goldstein, Cialdini, & Griskevicius, 2008)[6]. Morling (2014) points out that many psychology studies have high internal and construct validity but sometimes sacrifice external validity.

Question 18

How to gather participants:

Answer 18

There are several approaches to recruiting participants. One is to use participants from a formalsubjectpool—an established group of people who have agreed to be contacted about participating in research studies. . .Participants who are not in subject pools can also be recruited by posting or publishing advertisements or making personal appeals to groups that represent the population of interest.

Question 19

Marks of a volunteer subject

Answer 19

there is good evidence that on average, volunteers have the following characteristics compared with non-volunteers (Rosenthal & Rosnow, 1976)[1]:

They are more interested in the topic of the research.

They are more educated.

They have a greater need for approval.

They have higher IQ.

They are more sociable.

They are higher in social class.

Question 20

Experimenter expectancy effect

Answer 20

When the experimenter’s expectations about how participants “should” behave in the experiment affect how the participants behave.

Question 21

How to standardize a procedure:

Answer 21

The way to minimize unintended variation in the procedure is to standardize it as much as possible so that it is carried out in the same way for all participants regardless of the condition they are in. Here are several ways to do this:

Create a written protocol that specifies everything that the experimenters are to do and say from the time they greet participants to the time they dismiss them.

Create standard instructions that participants read themselves or that are read to them word for word by the experimenter.

Automate the rest of the procedure as much as possible by using software packages for this purpose or even simple computer slide shows.

Anticipate participants’ questions and either raise and answer them in the instructions or develop standard answers for them.

Train multiple experimenters on the protocol together and have them practice on each other.

Be sure that each experimenter tests participants in all conditions.

Question 22

It is very important to keep a ___ ____ of experiments

Answer 22

good record

Question 23

Manipulation check

Answer 23

Verifying the experimental manipulation worked by using a different measure of the construct the researcher is trying to manipulate.

Question 24

It is always a good idea to conduct a____ ____of your experiment.

Answer 24

pilot test

Question 25

questions that can be answered by conducting a pilot test:

Answer 25

There are several important questions that you can answer by conducting a pilot test:

Do participants understand the instructions?

What kind of misunderstandings do participants have, what kind of mistakes do they make, and what kind of questions do they ask?

Do participants become bored or frustrated?

Is an indirect manipulation effective? (You will need to include a manipulation check.)

Can participants guess the research question or hypothesis (are there demand characteristics)?

How long does the procedure take?

Are computer programs or other automated procedures working properly?

Are data being recorded correctly?