Research Methods Psych Ch 7: The experimental research strategy

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

Dr. Jones is interested in studying how indoor lighting can influence people's moods during the winter. A sample of 100 households is selected. Fifty of the homes are randomly assigned to the bright-light condition where Dr. Jones replaces all the lights with 100-watt bulbs. In the other 50 houses, all the lights are changed to 60-watt bulbs. After two months, Dr. Jones measures the level of depression for the people living in the houses. In this example, how many dependent variables are there?

1

In order to establish an unambiguous relationship between two variables, it is necessary to eliminate the possible influence of which of the following variables?

Confounding variables

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.

True or False: A field study involves creating a real-world atmosphere in a laboratory to duplicate a natural environment or situation; a simulation involves moving an experiment from the laboratory into the real-world environment.

False

True or False: In the short run, a random process guarantees a balanced result, however, in the long run there is a chance that randomization will not work.

False

In an experiment, what is the purpose for manipulating the independent variable?

It helps establish the direction of the relationship and it helps eliminate the third-variable problem.

A researcher exposes people to a stressful situation (such as public speaking) to examine the effect of stress on depressed mood. Why would the researcher also include a measure of stress?

It is a manipulation check.

Which of the following characteristics are 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 that can be used to evaluate the size of the treatment effect.

Although field studies tend to have higher external validity than traditional laboratory studies, what risk do they tend to have?

Lower internal validity

In an experiment comparing two treatments, the researcher assigns participants to treatment conditions so that each condition has fifteen 7-year-old children and ten 8-year-old children. For this study, what method is being used to control participant age?

Matching

Which of the following is the primary goal for randomly assigning participants to treatment conditions in an experiment?

Minimize the likelihood that a participant variable (such as age or gender) becomes a confounding variable

In an experiment, a researcher always manipulates the independent variable.

True

True or False: An experiment always involves comparison of measures of the dependent variable across different levels of the independent variable. To accomplish this, a treatment condition (an experimental condition) and a no-treatment condition (a control condition) often are created.

True

True or False: Extraneous variables become confounds when they change systematically along with the independent variable. After identifying a short list of extraneous variables that have the potential to become confounding variables, it is possible to actively or passively control these variables.

True

True or False: If you are using a random process (such as a coin toss) to assign people to treatment conditions, it is still possible for all the high-IQ individuals to be assigned to the same condition.

True

True or False: Randomization does not guarantee that extraneous variables are really controlled; rather, it uses chance to control variables.

True

True or False: The two basic characteristics that distinguish the experimental research strategy from other research strategies are (1) manipulation of one variable while measuring a second variable and (2) control of extraneous variables.

True

True or False: The two standard methods of active control are (1) holding a variable constant and (2) matching values across the treatment conditions.

True

True or False: There are two general categories of control conditions: (1) the no-treatment control condition, a condition that involves no treatment whatsoever (participants receive a zero level of the independent variable); and (2) the placebo control condition, a condition that involves the appearance of a treatment but from which the active, effective elements have been removed.

True

True or False: To establish a cause-and-effect relationship between two variables, an experiment necessarily creates an artificial, controlled environment in which the two variables being studied are isolated from outside influences. This high level of control required by an experiment can be a threat to external validity.

True

True or False: To establish an unambiguous causal relationship between the independent and dependent variables, it is necessary to eliminate the possible influence of a confounding variable.

True

A placebo control condition is...

a condition in which participants receive a placebo instead of the actual treatment.

In an experiment, a no-treatment control condition is...

a condition in which the participants do not receive the treatment being evaluated.

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

a field study.

The placebo effect refers to...

a positive response by a participant to an inert medication that has no real effect on the body. The placebo effect occurs simply because the individual thinks the medication is effective.

In an experiment, a treatment condition is...

a situation or environment characterized by one specific value of the manipulated variable. An experiment contains two or more treatment conditions that differ according to the values of the manipulated variable.

Extraneous variables are...

all variables in the study other than the independent and dependent variables.

A manipulation check is...

an additional measure to assess how the participants perceived and interpreted the manipulation and/or to assess the direct effect of the manipulation.

An experiment or a true experiment attempts to...

show that changes in one variable are directly responsible for changes in a second variable.

In an experiment, the _________ is the condition in which the treatment is administered and the ________ is the condition in which the treatment is not administered.

experimental condition....control condition

In an experiment, manipulation consists of...

identifying the specific values of the independent variable to be examined and then creating a set of treatment conditions corresponding to the set of identified values.

Holding a variable constant is a technique for removing one threat to ________, but it can limit the ________ of an experiment.

internal validity, external validity

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

Field study is...

research conducted in a place that the participant or subject perceives as a natural environment.

A simulation is...

the creation of conditions within an experiment that simulate or closely duplicate the natural environment in which the behaviors being examined would normally occur.

Levels are...

the different values of the independent variable selected to create and define the treatment conditions.

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. What problem is demonstrated by this example?

the directionality problem

The experimental research strategy establishes...

the existence of a cause-and effect relationship between two variables. To accomplish this goal, an experiment manipulates one variable while a second variable is measured and other variables are controlled.

Random assignment is...

the use of a random process to assign participants to treatment conditions.

Randomization is...

the use of a random process to help avoid a systematic relationship between two variables.

In an experiment, the independent variable is...

the variable manipulated by the researcher.

The dependent variable is...

the variable that is observed for changes to assess the effects of manipulating the independent variable. The dependent variable is typically a behavior or a response measured in each treatment condition.