PSYC 3980 – Chapter 10 – [Introduction to Simple Experiments]

Experiment
A study in which one variable is manipulated and the other is measured
Manipulated Variable
A variable in an experiment that a researcher controls, such as by assigning participants to its different levels (values).
measured variable
A variable in an experiment whose levels (values) are observed and recorded
independent variable
A variable that is manipulated in an experiment. In a multiple-regression analysis, a predictor variable used to explain variance in the criterion variable.
condition
One of the levels of the independent variable in an experiment
dependent variable
An an experiment, the variable that is measured. In a multiple-regression analysis, the single outcome, or criterion variable, the researchers are most interested in understanding or predicting
control variable
A potential variable that an experimenter holds constant on purpose.
comparison group
A group in an experiment whose level on the independent variable differs from those of the treatment group in some intended and meaningful way.
control group
A level of an independent variable that is intended to represent “no treatment” or a neutral condition.
treatment group
The participants in an experiment who are exposed to the level of the independent variable that involves a medication, therapy, or intervention.
placebo group
A control group that is exposed to an inert treatment (e.g. a sugar pill).
confound
A general term for a potential alternative explanation for a research finding (a threat to internal validity).
design confound
A threat to internal validity in an experiment in which a second variable happens to vary systematically along with the independent variable and therefore is an alternative explanation for the results.
systemic variability
In an experiment, the levels of a variable coinciding in some predictable way with experimental group membership, creating a potential confound.
unsystematic variability
In an experiment, when levels of a variable fluctuate independently of experimental group membership contributing to variability within groups.
selection effect
A threat to internal validity that occurs in an independent-groups design when the kinds of participants at one level of the independent variable are systematically different from those at the other level.
random assignment
The use of a random method (e.g. flipping a coin) to assign participants to different experimental groups.
matched groups
An experimental design technique in which participants who are similar on some measured variable are grouped into sets; the numbers of each matched set are then randomly assigned to different experimental conditions.
independent-groups design
An experimental design in which different groups of participants are assigned to different levels of the independent variable, such that each participant experiences only one level of the independent variable.
posttest-only design
An experiment using an independent-groups design in which participants are tested on the dependent variable only once.
pretest/posttest design
An experiment using an independent-groups design in which participants are tested on the key dependent variable twice: once before and once after exposure to the independent variable.
concurrent-measures design
An experiment using a within-groups design in which participants are exposed to all the levels of an independent variable at roughly the same time, and a single attitudinal or behavioral preference is the dependent variable.
repeated-measures design
An experiment using a within-groups design in which participants respond to a dependent variable more than once, after exposure to each level of the independent variable.
power
order effect
practice effect
carryover effect
counterbalancing
full counterbalancing
partial counterbalancing
Latin square
demand characteristic
manipulation check
pilot study
Which of these is not a drawback of a within-groups design?

Extraneous differences are held constant across conditions.
Participants cannot be returned to their original state after each condition.
Demand characteristics may result from hypothesis guessing with repeated testing.
Order effects can threaten internal validity.

Extraneous differences are held constant across conditions.
Which of these does not need to be considered as an alternative explanation of the results in a within-groups design experiment?

fatigue
selection
practice
boredom

selection
In a business class experiment on the endowment effect, Theo is comparing the value of a coffee mug to someone who owns it and is selling it to someone who is buying it. The endowment effect describes the tendency of sellers to value something they own more than buyers do. Participants are randomly assigned to be buyers or sellers of a mug with their first name on it. Buyers select the maximum price they would pay for the mug. Sellers select the minimum price they would accept for the mug. What is the independent variable in this experiment?

role of the participant
price that the buyer will pay
price that the seller will accept
name of the participant

role of the participant
What design is an experiment in which participants are randomly assigned to independent variable groups then tested on the dependent variable once?

within-groups
repeated measures
pretest/posttest
posttest only

posttest only
In psychology lab, Tetiana is conducting an experiment on depth perception using the Howard-Dolman box. Inside the box are two vertical rods and a horizontal ruler. The participant manipulates the rods until they appear to be aligned at the same distance away, then the experimenter measures how far out of alignment they are. There are three conditions: left eye only, right eye only, and both eyes. Tetiana is using a repeated measures design. How is the independent variable being manipulated in Tetiana’s design?

independent groups
within-groups
concurrently
as a participant variable

within-groups
In a word list-learning experiment, participants are given a list of words to study for 3 minutes and then, following a delay, are asked to recall the list. The length of time between the study period and the recall is being manipulated: it is 2 minutes, 5 minutes, or 10 minutes. Which of the following is a confounding variable?

All participants in the 2-minute condition are tested at 8:00a.m., those in the 5-minute condition are tested at noon, and those in the 10-minute condition are tested at 4:00 p.m.
The same list is used for each condition and is randomized for each participant.
The three groups are run simultaneously in three different rooms, and the room for each condition is randomly chosen before each group arrives.
Three different experimenters administer the task and rotate which condition they are administering.

All participants in the 2-minute condition are tested at 8:00a.m., those in the 5-minute condition are tested at noon, and those in the 10-minute condition are tested at 4:00 p.m.
Which of the following is not a method to interrogate construct validity in an experimental design?

pilot studies
checking for statistical significance
manipulation checks
adding additional conditions

checking for statistical significance
In psychology lab, Tetiana is conducting an experiment on depth perception using the Howard-Dolman box. Inside the box are two vertical rods and a horizontal ruler. The participant manipulates the rods until they appear to be aligned at the same distance away, then the experimenter measures how far out of alignment they are. There are three conditions: left eye only, right eye only, and both eyes. Tetiana is using a repeated measures design. What is the independent variable in this experiment?

depth perception
number of trials
disparity from perfect alignment
eye/eyes used

eye/eyes used
In a business class experiment on the endowment effect, Theo is comparing the value of a coffee mug to someone who owns it and is selling it to someone who is buying it. The endowment effect describes the tendency of sellers to value something they own more than buyers do. Participants are randomly assigned to be buyers or sellers of a mug with their first name on it. Buyers select the maximum price they would pay for the mug. Sellers select the minimum price they would accept. Which validity is concerned with applying the results to more expensive objects?

construct
internal
statistical
external

external
Which of these is not an advantage of within-groups designs?

elimination of practice effects
assurance of equivalence of the groups
requirement of fewer participants
more statistical power

elimination of practice effects
In a business class experiment on the endowment effect, Theo is comparing the value of a coffee mug to someone who owns it and is selling it to someone who is buying it. The endowment effect describes the tendency of sellers to value something they own more than buyers do. Participants are randomly assigned to be buyers or sellers of a mug with their first name on it. Buyers select the maximum price they would pay for the mug. Sellers select the minimum price they would accept for the mug. How does Theo control for selection effects?

by using a control group
by using matched-groups design
by random assignment of participants
by using a pretest/posttest design

by random assignment of participants
What does use of a Latin square assure with regard to conditions in a within-groups experiment?

that each participant will have a unique order of the conditions
that the order of the conditions will be randomized for each group
that each condition appears in each position within the order at least once
that all possible orders of conditions will be used

that each condition appears in each position within the order at least once
In psychology lab, Tetiana is conducting an experiment on depth perception using the Howard-Dolman box. Inside the box are two vertical rods and a horizontal ruler. The participant manipulates the rods until they appear to be aligned at the same distance away, then the experimenter measures how far out of alignment they are. There are three conditions: left eye only, right eye only, and both eyes. Tetiana is using a repeated measures design. She plans to have 60 participants and to use full counterbalancing. How many participants will be in each group?

six
ten
twenty
thirty

ten
In a word list-learning experiment, participants are given a list of words to study for 3 minutes and then, following a delay, are asked to recall the list. The length of time between the study period and the recall is being manipulated: it is 2 minutes, 5 minutes, or 10 minutes. Since different groups need different amounts of time, the first 25 participants who arrive are assigned to the 10-minute group, the next 25 are assigned to the 5-minute group, and the final 25 are assigned to the 2-minute group. What confound does this create?

demand characteristic
selection effect
experimenter bias
carryover effect

selection effect
What is a variable that the experimenter holds constant on purpose?

dependent
independent
control
confound

control
According to Cohen’s conventions for effect size, how do you describe an effect size when d = 0.50?

not existent
weak
moderate
strong

moderate
What type of group is a level of the independent variable that is intended to represent a neutral condition?

treatment
comparison
experimental
control

control
In a study of the span of apprehension, or how many objects you can assess (report seeing) after a brief exposure, the length of exposure is held constant and the number of objects is varied, from one to twelve. After a large number of trials, the percentage correct for each number of objects is found. What is the dependent variable in this experiment?

the percentage correct
the number of objects
the length of exposure
the number of trials

the percentage correct
In psychology lab, Tetiana is conducting an experiment on depth perception using the Howard-Dolman box. Inside the box are two vertical rods and a horizontal ruler. The participant manipulates the rods until they appear to be aligned at the same distance away, then the experimenter measures how far out of alignment they are. There are three conditions: left eye only, right eye only, and both eyes. Tetiana is using a repeated measures design. What is the dependent variable in this experiment?

distance out of alignment of the rods
how long the participant takes to complete the experiment
improvement in performance by the participant
eye/eyes used

distance out of alignment of the rods
In a business class experiment on the endowment effect, Theo is comparing the value of a coffee mug to someone who owns it and is selling it to someone who is buying it. The endowment effect describes the tendency of sellers to value something they own more than buyers do. Participants are randomly assigned to be buyers or sellers of a mug with their first name on it. Buyers select the maximum price they would pay for the mug. Sellers select the minimum price they would accept for the mug. What is the dependent variable in this experiment?

role of the participant
value selected for the mug
type of mug
name of the participant

value selected for the mug
In a study of the span of apprehension, or how many objects you can assess (report seeing) after a brief exposure, the length of exposure is held constant and the number of objects is varied, from one to twelve. After a large number of trials, the percentage correct for each number of objects is found. What is the independent variable?

the percentage correct
the number of objects
the length of exposure
the number of trials

the number of objects
In psychology lab, Tetiana is conducting an experiment on depth perception using the Howard-Dolman box. Inside the box are two vertical rods and a horizontal ruler. The participant manipulates the rods until they appear to be aligned at the same distance away, then the experimenter measures how far out of alignment they are. There are three conditions: left eye only, right eye only, and both eyes. Tetiana is using a repeated measures design. She finds that d = 1.53. What effect size is this?

weak
moderate
strong
This cannot be determined without knowing the number of participants.

strong
How many possible orders for full counterbalancing are there in a study with four conditions?

four
eight
sixteen
twenty-four

twenty-four
In a business class experiment on the endowment effect, Theo is comparing the value of a coffee mug to someone who owns it and is selling it to someone who is buying it. The endowment effect describes the tendency of sellers to value something they own more than buyers do. Participants are randomly assigned to be buyers or sellers of a mug with their first name on it. Buyers select the maximum price they would pay for the mug. Sellers select the minimum price they would accept. Which validity is concerned with the significance of the difference in the prices?

construct
internal
statistical
external

statistical
In what type of design does the experimenter sort the participants from lowest to highest of a relevant trait, form groups based on similar scores on that trait, then randomly assign those within each group to the different conditions?

independent groups
concurrent measures
matched-groups
within-groups

matched-groups