Question 1

Random assignment is a procedure that psychological researchers apply to their

Accepted Answer

Random assignment is the procedure of assigning participants to different experimental conditions or groups, and is a key aspect of experimental design in psychology. This helps to reduce the effects of individual differences, such as personality traits or prior experiences, and allows the researcher to make stronger causal claims about the relationship between the independent variable(s) and the dependent variable(s).

Question 2

The advantage of randomly assigning participants to the experimental group and the control group is that random assignment

Accepted Answer

Random assignment helps to even out any potential differences between the groups at the start of the experiment, which reduces the possibility of confounding variables affecting the results.

Question 3

Researchers collected information from 500 children on the amount of violent TV they watched. They also collected ratings of how aggressive these children were. The researchers measured TV watching and aggressiveness when these same subjects more than fifteen years later. The highest correlation was observed between

Accepted Answer

The highest correlation was observed between childhood violent TV watching and adult aggression, as the researchers measured TV watching and aggressiveness when these same subjects more than fifteen years later. This suggests that childhood exposure to violent media can have long-lasting effects on aggressive behavior in adulthood.

Question 4

How does an experimenter try to equate the experimental group and the control group at the start of the experiment?

Accepted Answer

Random assignment is the most commonly used method to equate the experimental group and the control group at the start of the experiment. It ensures that each participant has an equal chance of being assigned to either the experimental or the control group, reducing any potential biases or confounding variables. Elimination of independent variables and statistical tests can be used to control for differences between the groups during the experiment, but they do not necessarily equate the groups at the start. Demand characteristics are a potential source of bias that can affect both groups equally and are not a method of equating the groups.

Question 5

Which cause-and-effect conclusion, if any, can we draw from the correlational studies of watching violent television?

Accepted Answer

While correlational studies have found a relationship between watching violence on television and aggressive behavior, it is impossible to draw a cause-and-effect conclusion from correlational data. Other factors, such as pre-existing aggression, could be responsible for the relationship observed in the studies. Therefore, the most accurate conclusion is that we can draw none of these conclusions.

Question 6

The experimental group in one study receives a free copy of the study guide so that the experimenter can determine the effect of the study guide on test performance. What will the control group in this experiment do?

Accepted Answer

The control group in this experiment will take all the same tests as the experimental group, but without using the study guide. This allows the experimenter to determine if any differences in test performance are due to the use of the study guide or other factors. Option A, D, and C are not relevant to the control group's role in the study.

Question 7

To examine the value of looking at old tests, Professor King hands out copies of old tests to the first 20 students who come to class one day. Later she finds that these students got better grades than the other students in the class. What is wrong with this experiment?

Accepted Answer

The experiment lacks random assignment to groups, meaning that the group of students who received old tests could have been inherently different from the other students in the class. This could account for the difference in grades rather than the use of old tests. The other answer choices do not apply to this situation.

Question 8

To test the value of the study guide, Professor Lewis gives a free copy to the students sitting in the first two rows of class. Later she finds that these students got better grades than the students in the back of the room (who didn't get study guides). What is wrong with this experiment?

Accepted Answer

The lack of random assignment to groups means that there could be other variables (such as motivation or intelligence levels) that are causing the difference in grades between the two groups, rather than just the study guide itself. Without random assignment, the experiment cannot definitively show that the study guide is the cause of the better grades.

Question 9

An instructor gives weekly tests to one class and just one midterm exam to another class. Both classes get the same final exam. The instructor compares performances on the final exam to see whether the weekly tests affected students' performance. What is the independent variable in this experiment?

Accepted Answer

The independent variable is the variable that the researcher manipulates or changes in the experiment. In this case, the independent variable is the number of tests before the final, as this is the only variable that is different between the two classes being compared. The other variables (students' performance on the final exam, the difficulty of each test, and the number of students in each class) are all potential dependent variables that may be affected by the number of tests given before the final exam.

Question 10

In one study, the experimental group is subjected to loud, unpredictable noises to see whether or not those noises will affect performance on a memory task. What will the control group do?

Accepted Answer

The control group should perform the memory task without the unpredictable noises, which will allow researchers to compare the effects of the manipulation (loud noises) on the experimental group's performance. Option A (doing nothing) is incorrect because the control group needs to perform some task to be compared to the experimental group. Option C (listening to noises without task) is not appropriate because it doesn't account for the effects of task performance on memory. Option D (controlling noises for the experimental group) doesn't have a clear purpose since the point is to test the effect of the noises on memory performance.

Question 11

Random assignment is

Accepted Answer

Random assignment is the process of assigning participants to different groups (e.g. experimental group, control group) in a way that each participant has an equal chance of being assigned to any group. This helps eliminate potential biases and allows researchers to make causal inferences about the effects of the independent variable on the dependent variable.

Question 12

To test the effect of an informal atmosphere on class performance, Professor Hall dresses in shorts and bare feet for his morning class and in conventional clothing for his afternoon class. He then counts the number of "intelligent questions" in each class and reports more in the class for which he wore shorts. What are the two things wrong with this experiment?

Accepted Answer

The experiment lacks random assignment because students are not randomly assigned to the morning or afternoon class, which could introduce confounding variables related to the time of day. Additionally, the observations are not blind; Professor Hall knows which condition he is observing, which could bias his assessment of what constitutes an "intelligent question."

Question 13

Psychology experiments have typically shown that

Accepted Answer

Numerous studies have shown that watching violent movies and TV programs can lead to increased aggressive behavior, at least temporarily. While some experiments have shown that individuals who watch violent movies may feel a sense of catharsis or release, overall the evidence suggests that exposure to violent media can have negative effects on behavior. There is no evidence to support choices A, B, or C.

Question 14

An experimenter tests the reading skills of some 10-year-old children, puts them on a low-fat diet for 6 months, retests their reading skills, and finds that most show a significant improvement in their reading. The experimenter concludes that a low-fat diet improves intellectual development. One major defect in this study is the lack of any

Accepted Answer

The major defect in the study is the lack of a control group. Without a control group, it is impossible to determine if the improvement in reading skills was actually caused by the low-fat diet or if it was due to some other factor such as the passage of time or the act of being tested again.

Question 15

Which of the following is the BEST conclusion from the research discussed on the effects of watching television violence and aggressive behavior?

Accepted Answer

The research discussed in the question supports the conclusion that both experiments and correlational studies indicate that viewing violence is associated with greater aggressiveness. This means that there is consistent evidence from different types of studies that watching violent media can lead to more aggressive behavior in individuals.

Question 16

Research participants viewed either violent or nonviolent films for four consecutive nights. On the fifth night, half the participants were told by the experimenter that their performance was terrible and the other half were told they had done well on some task. What group showed the most hostility on the fifth night?

Accepted Answer

The group that watched violent films and were told their performance was terrible showed the most hostility on the fifth night. This is because they experienced both the effects of the violent films and the negative feedback from the experimenter, which may have increased their aggression. The other options are not supported by the scenario given.

Question 17

The control group in an experiment is a group that

Accepted Answer

The control group in an experiment is a group that is treated the same as the experimental group except for the treatment the experiment is designed to test. This allows researchers to compare the effects of the treatment to a group that did not receive the treatment, providing a basis for evaluating whether the treatment had a significant effect. Options A, B, and C are not accurate descriptions of the control group.

Question 18

To test the effects of eating on learning, Professor Lee permits her morning class to bring snacks to class but forbids her afternoon class from bringing snacks. To measure performance, she counts the number of "intelligent questions" asked by students in each class, and reports getting more such questions in the morning class. What are two serious flaws in this experiment?

Accepted Answer

The experiment lacks random assignment, which means that the groups may not be equivalent in other ways beyond the variable being tested (snacking). This could introduce confounding variables. Additionally, there is a lack of blind observations, which means that the experimenter's expectations may bias their observations of the students. There are no issues with the number of dependent or independent variables, and demand characteristics or the presence of too many independent variables are not relevant to this experiment.

Question 19

Professor Middlebrain notes that rats in the first 10 cages, which were injected with salt water, are calm. Rats in the last 10 cages, which were injected with distilled water, are aggressive. He concludes that salt decreases aggressiveness. What is wrong with this study?

Accepted Answer

The study lacks random assignment, which means that there is no control over individual differences in the two groups. It is possible that there were pre-existing differences between the rats that were assigned to the different conditions, which could explain the observed results. Additionally, there may be other confounding variables that were not controlled for, such as differences in the rat's age or gender. Therefore, it is not possible to draw a valid conclusion about the effect of salt on aggressiveness based on this study alone.

Question 20

If each subject in an experiment has an equal chance of being in the experimental group, then the experiment has

Accepted Answer

Random assignment means that each subject has an equal chance of being in the experimental group, which helps to eliminate potential confounds and establish cause-and-effect relationships. The other options (demand characteristics, correlation, and statistical significance) do not directly relate to the concept of equal assignment in experimental design.

Quiz 2: Scientific Methods in Psychology