4. Gerontologists interested in the effects of aging on reaction time have two groups of subjects take a test in which they must indicate as quickly as possible whether a probe word is a member of a previous set of words. One group of subjects is between the ages of 25 and 45, whereas the other group is between the ages of 55 and 75. The time it takes to make the response is measured. In this study:

a. What is the independent variable?
b. What is the dependent variable?
c. Identify the control and experimental groups.
d. Is the independent variable manipulated, or is it a participant variable?

And your answer is? Your text undoubtedly explains these terms. If not, use your search engine by typing in keywords such as "independent variable in research", click "enter" and read about the topic. Do that as often as necessary to understand these concepts.

a. The independent variable in this study is the age group of the subjects. The two groups are divided based on age, with one group between the ages of 25 and 45 and the other group between the ages of 55 and 75.

b. The dependent variable in this study is the time it takes for the subjects to make a response.

c. The control group in this study would be the group of subjects between the ages of 25 and 45. The experimental group would be the group of subjects between the ages of 55 and 75.

d. The independent variable in this study is a participant variable, as the researchers are not actively manipulating the age of the subjects but rather studying the effects of natural aging on reaction time.

a. The independent variable in this study is the age group of the subjects. The subjects are divided into two groups based on their ages: 25-45 and 55-75.

b. The dependent variable in this study is the time it takes to make the response. This variable is measured and recorded for each subject in both age groups.

c. The control group in this study would be the group of subjects between the ages of 25-45. The experimental group would be the group of subjects between the ages of 55-75. The control group serves as a comparison group to assess the effects of aging on reaction time.

d. In this study, the independent variable is a participant variable. The researchers are not manipulating the age of the subjects; they are simply observing and comparing subjects across different age groups. Participants are being assigned to their respective groups based on their age range.