Chapter 7 Psych 226

A researcher is performing an experiment to determine whether eating chocolate can improve memory. Measurements of memory in this experiment would be the ____ variable.

dependent

Dr. Ramos is interested in studying how indoor temperature can influence people's sleep quality during the summer. A sample of 100 households is selected in which the residents keep their houses at 76 degrees during the summer. The residents wear a monitoring device that measures their sleep cycles for several nights to get baseline readings. Then, 50 of the homes are randomly assigned to the warm temperature condition in which the residents agree to keep their houses at 82 degrees Fahrenheit. In the other 50 houses, the residents agree to keep their houses at 70 degrees. For several nights, Dr. Ramos collects the sleep data for the people living in the houses to see how the residents' sleep patterns have changed. In this example, the sleep quality of participants is the ____ variable.

dependent

holding a variable constant is a technique for removing one threat to ____ but it can limit the ____ of an experiment

internal validity; external validity

The specific treatment conditions that are used in an experiment are called the ____.

levels of the independent variable

Although field studies tend to have higher external validity that traditional laboratory studies, they also tend to have ____.

lower internal validity

A researcher exposes people to a stressful situation (such as public speaking) to examine the effect of stress on depressed mood. The researcher includes a measure of stress as a ____.

manipulation check

Which technique provides useful information when there are small changes from one treatment condition to another, when simulations are used or when a placebo is used?

manipulation checks

In an experiment comparing two treatments, the researcher assigns participants to treatment conditions so that each condition has 10 adults with college degrees and 10 adults with high-school diplomas only. For this study, what method is being used to control participant education level?

matching

A researcher attempts to recreate the real world in the laboratory. This type of research is called a ____.

simulation study

A researcher has observed that adults who are more optimistic tend to have a higher level of life satisfaction than adults who are less optimistic. However, the researcher suspects that the apparent relationship may be explained by the fact that some people have positive things happen in their lives, which causes them to be more optimistic and satisfied with their lives compared to people who have bad things happen in their lives and therefore have a more negative outlook on things. This is an example of the ____.

third-variable problem

In an experiment, a confounding variable is a(n) ____.

threat to internal validity

In an experiment, participants are usually assigned to treatments using random assignment. The reason for using random assignment is ____.

to help control extraneous variables

In an experiment, participants are randomly assigned to treatment conditions ____.

to help protect the internal validity of the study

Dr. Nguyen is studying how amount of sleep influences mood for kindergarteners. A sample of 100 children is selected. Fifty children are allowed to sleep for 11 hours each night. The other 50 children are awoken after 8 hours. After three nights, Dr. Nguyen records the mood for each child and compares the two groups of scores. In this example, how many levels are there for the independent variable?

2

In an experiment, a researcher manipulates people's mood to determine whether changes in mood cause changes in memory performance. However, the researcher is not sure that the manipulation is really causing people's mood to change. In this case, what should the researcher do?

Add a manipulation check by measuring mood.

A researcher designs a study to determine whether female preschoolers prefer sweetened or unsweetened cereal. The researcher uses a box of sweetened colorful cereal and a box of unsweetened tan colored cereal. The research finds that the group of preschoolers ate more of the sweetened colorful cereal and therefore prefers the sweetened cereal. Which two variables are confounded in this experiment?

Color of the cereal and sweetness of the cereal

What is the advantage of a simulation compared to a traditional laboratory study?

Increased external validity

Which characteristic is necessary for an extraneous variable to become a confounding variable?

It must change systematically when the independent variable is changed.

What is the purpose for using a control condition in an experiment?

It provides a baseline to evaluate the size of the treatment effect.

Why is a confounding variable unacceptable in a true experiment?

It threatens internal validity by providing an alternative explanation for the results.

What is the primary goal for randomly assigning participants to treatment conditions in an experiment?

Minimize the likelihood that a participant characteristic becomes a confounding variable.

How do studies using the experimental research strategy differ from other types of research?

Only experiments can demonstrate a cause-and-effect relationship between variables.

An experiment includes a treatment condition, a no-treatment control, and a placebo control. Which two conditions should be compared to determine the size of the effect that is actually caused by the treatment?

Placebo versus treatment

In New York State, the winter months produce higher heating bills and higher levels of depression. Although the numbers show that higher heating bills are related to higher levels of depression, what most likely explains this relationship?

The third-variable problem

Dr. Jones systematically varies the brightness in the laboratory (400, 800, and 1600 lumens) while holding other variables constant, and observes that the participants' activity level decreases as the brightness decreases. This illustrates ____.

a causal relationship between brightness and activity level

In an experiment, any variable that varies systematically with the treatment conditions and might influence the participants' scores is called a(n) ____ variable

confounding

In order to establish an unambiguous relationship between two variables, it is necessary to eliminate the possible influence of ____ variables.

confounding

In an experiment, manipulation of the independent variable requires ____.

creating at least two treatment conditions defined by two different levels of the independent variable

The measured variable in an experiment is the ____ variable.

dependent

A confounding variable is a variable that influences the ____.

dependent variable and varies systematically with the independent variable.

Research indicates the people who suffer from depression also tend to experience insomnia. However, it is unclear whether the depression causes insomnia or the lack of sleep causes depression. This is an example of the ____.

directionality problem

In an experiment, the purpose for manipulating the independent variable is to help ____.

establish the direction of the relationship and help eliminate the third variable problem

Dr. Ramos is interested in studying how indoor temperature can influence people's sleep quality during the summer. A sample of 100 households is selected in which the residents keep their houses at 76 degrees during the summer. The residents wear a monitoring device that measures their sleep cycles for several nights to get baseline readings. Then, 50 of the homes are randomly assigned to the warm temperature condition in which the residents agree to keep their houses at 82 degrees Fahrenheit. In the other 50 houses, the residents agree to keep their houses at 70 degrees. For several nights, Dr. Ramos collects the sleep data for the people living in the houses to see how the residents' sleep patterns have changed. Assuming that the study allows people to use as many or as few blankets as they like, number of blankets would be a(n) ____ variable in the experiment.

extraneous

A researcher moves an experiment out of the laboratory and into the real world. This type of research is called a ____.

field study

A researcher decides to use only participants that weigh between 150 and 160 pounds in an experiment comparing two treatment conditions. For this study, what method is being used to control participant weight?

holding constant

The manipulated variable in an experiment is the ____ variable.

independent

Researchers often use simulation experiments in an attempt to obtain the ____ of an experiment and still keep much of the ____ of research conducted in the real world.

internal validity; external validity

Dr. Sian varies the amount of a new sedative given to three groups of participants (0, 1, and 2 mg) and then observes the reaction for each group. The 0-mg condition represents the ____ condition.

no-treatment control

Dr. Ramos is interested in studying how indoor temperature can influence people's sleep quality during the summer. A sample of 100 households is selected in which the residents keep their houses at 76 degrees during the summer. The residents wear a monitoring device that measures their sleep cycles for several nights to get baseline readings. Then, 50 of the homes are randomly assigned to the warm temperature condition in which the residents agree to keep their houses at 82 degrees Fahrenheit. In the other 50 houses, the residents agree to keep their houses at 70 degrees. For several nights, Dr. Ramos collects the sleep data for the people living in the houses to see how the residents' sleep patterns have changed. In this study, the independent variable is the ____.

temperature of the houses

If a study finds that there is a strong relationship between two variables, this means that ____.

there is a relationship between the variables but causality has not been established