Question 1

Which of the following researchers probably worries most about the external validity of her studies?

Accepted Answer

Dr. Prentice, working as a consumer psychologist for the Target Corporation, is likely most concerned with external validity because her research needs to apply to real-world consumer behavior outside the laboratory setting to be useful for the corporation's objectives.

Question 2

When are manipulation checks usually done?

Accepted Answer

The answer of When are manipulation checks usually done?
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Question 3

In an experiment, the participants' ages would be a confounding variable if which of the following were true?

Accepted Answer

A confounding variable is an external variable that influences both the dependent variable and independent variable, causing a spurious association. In this case, if participants in one condition were older on average than those in another, age could influence the results outside of the experimental manipulation, making it a confounding variable.

Question 4

Why are confounding variables bad?

Accepted Answer

Confounding variables are bad because they provide an alternative explanation for any observed difference between conditions, reduce internal validity, and make it difficult to tell if the independent variable was responsible for the effect on the dependent variable.

Question 5

Which of the following independent variables would most likely require a manipulation check?

Accepted Answer

Manipulation checks are often used when the independent variable involves internal states or subjective experiences, such as participants' moods, to ensure that the intended manipulation has the desired effect. Variables like the amount of light, noise level, and number of items on an exam are external and more directly measurable, making manipulation checks less necessary for these conditions.

Question 6

Why do researchers randomly assign participants to conditions?

Accepted Answer

Randomly assigning participants to conditions helps control for extraneous variables that could affect the outcome of the study. This allows researchers to be more confident that any observed effects are due to the independent variable and not other factors.

Question 7

What is the main advantage of conducting an experiment using a within-subjects design rather than a between-subjects design?

Accepted Answer

Within-subjects design controls for individual differences between participants, which can be a major source of error in between-subjects designs. By allowing each participant to serve as their own comparison group, extraneous variables are controlled for and the effect of the independent variable can be more accurately assessed.

Question 8

A pilot test is a small-scale version of a study conducted to see if the procedure works as planned.

Accepted Answer

A pilot test is indeed a small-scale version of a study that is conducted to test whether the procedure works as planned. It is often conducted before a full-scale study to identify any potential problems or issues and to make necessary changes before beginning the larger study.

Question 9

Which of the following is true?

Accepted Answer

Confounding variables are a type of extraneous variable that specifically affect the relationship between the independent and dependent variables, making them a subset of extraneous variables.

Question 10

What are the two defining features of an experiment?

Accepted Answer

The two defining features of an experiment are manipulation of an independent variable and control of extraneous variables. Manipulating the independent variable allows the researcher to see the effect of this variable on the dependent variable while controlling extraneous variables helps isolate the effect of the independent variable.

Question 11

Research on placebos has shown which of the following?

Accepted Answer

Research on placebos has shown that even fake surgery can have positive effects. Studies have found that patients who received a placebo surgery for conditions such as osteoarthritis of the knee or angina reported similar levels of improvement as patients who received the actual surgery. This suggests that the placebo effect can be powerful enough to produce real physiological changes in the body.

Question 12

Imagine that you are a participant in an experiment on the effects of morning exercise on mathematics performance. If this study uses a within-subjects design, which of the following would you do?

Accepted Answer

With a within-subjects design, participants are exposed to both the experimental condition (morning exercise) and the control condition (no morning exercise). In this case, the participant would take a math test after having exercised and after not having exercised. Option A describes this type of design, while options B, C, and D do not include both conditions.

Question 13

A researcher who uses ONLY within-subjects designs will NEVER have which of the following problems?

Accepted Answer

Within-subjects designs involve the same participants being exposed to all conditions of the experiment, which inherently controls for individual differences such as intelligence, because each participant serves as their own control. This design does not eliminate practice effects, context effects, or the possibility of non-significant results, but it does control for participant-specific variables like intelligence.

Question 14

A researcher is conducting a study in which the dependent variable is mental concentration. If it is a within-subjects design with lots of different conditions, then which of the following is most likely to be a problem for the researcher?

Accepted Answer

In a within-subjects design with many conditions, participants may become tired or fatigued, which can affect their performance on tasks requiring mental concentration.

Question 15

In an experiment, the different levels of the independent variable are referred to as which of the following?

Accepted Answer

Levels of the independent variable are called conditions. Factors refer to the different things that can influence a study or experiment, means refer to the average value of a set of data, and variables refer to any characteristic that can take on different values in a study or experiment.

Question 16

A researcher is interested in the effects of drinking different amounts of alcohol on a person's ability to perform a mental arithmetic task. Which of the following would be a problem for this researcher if she wanted to use a within-subjects design with counterbalancing?

Accepted Answer

Using a within-subjects design with counterbalancing requires testing each participant on at least two different conditions. In this case, the researcher would have to test each participant on a mental arithmetic task under both the influence of alcohol and without alcohol. This may require testing each participant on two different days to avoid carryover effects (such as hangovers) that could affect performance on subsequent trials.

Question 17

Which of the following nonintuitive results has been obtained using a between-subjects design?

Accepted Answer

The answer of Which of the following nonintuitive results has...

Question 18

Experiments are generally _____.

Accepted Answer

Experiments are generally high in internal validity because they allow researchers to establish cause-and-effect relationships between variables by controlling for extraneous variables and manipulating independent variables.

Question 19

Imagine an experiment with one independent variable: noise level (quiet vs. noisy). If the researcher is using a between-subjects design and wants to have 20 participants per condition, how many participants will he need all together?

Accepted Answer

A between-subjects design means that there will be two separate groups of participants: one group exposed to quiet conditions and another group exposed to noisy conditions. Each group should have 20 participants, so in total the researcher will need 40 participants. Therefore, the correct answer is C.

Question 20

Guillermo conducts an experiment with two conditions using a within-subjects design. If he is counterbalancing, what does this mean?

Accepted Answer

Counterbalancing means that participants are assigned to different orders of the conditions to eliminate any order effects, such as fatigue or practice. In option C, half of the participants receive Condition A followed by Condition B, while the other half receives Condition B followed by Condition A. This ensures that any effects of the order are evenly distributed across conditions.

Quiz 6: Experimental Research