Question

The following paragraphs describe a series of hypothetical experiments, each of which involves one or more design flaws. Please read the paragraphs and match them to what went wrong.

options are: demand characteristics, missing a control group, extraneous variable(s) present, placebo effect

A group of psychologists wants to determine whether scream therapy actually helps people feel better. To test this, they recruit a number of subjects who have recently complained of extreme nervousness, and they carefully measure their anxiety using a series of psychological tests. They then invite each person to enter a special sound chamber, and they encourage the person to scream as loudly as possible. After the subjects do so, the researchers administer the same tests again, and they discover that the subjects say that they feel much less anxious. Furthermore, the tests also show that the subjects are less anxious than they used to be.

A researcher wanted to determine whether a new antianxiety drug Streszac was effective. He tested a group of subjects who suffer from generalized anxiety disorder using a series of psychological tests. Then, subjects are randomly assigned to either an experimental group who receives the Streszac and a control group who does not. After 3 months of treatment, the participants who received Streszac show significantly less anxiety than the control group.

A researcher wants to discover if people can read her mind. Her procedure is as follows: she carefully shuffles a deck of cards and then looks at the top card. She nods to the subject across from her and tells him or her to try to guess what suit it is. The odds are that the subject should guess only 25% correctly, but the subjects consistently do much better than that.

A psychologist wants to determine whether love and affection will make an adult monkey more active. He starts off with a group of 12 monkeys and randomly assigns them to either the experimental group or the control group. Every day, the psychologist plays with the animals in the experimental group but not with the ones in the control group. At the same time, he is careful to be sure that both groups get enough food and water.  After one month, he carefully measures the activity level of all of the animals and discovers that indeed the experimental animals are more active. Based on this result he concludes that love and affection caused animals to become more active.

from the options up top we have to pick which flaw goes with the experiment.

Answer 1

1) A group of psychologists wants to determine whether scream therapy actually helps people feel better. To test this, they recruit a number of subjects who have recently complained of extreme nervousness, and they carefully measure their anxiety using a series of psychological tests. They then invite each person to enter a special sound chamber, and they encourage the person to scream as loudly as possible. After the subjects do so, the researchers administer the same tests again, and they discover that the subjects say that they feel much less anxious. Furthermore, the tests also show that the subjects are less anxious than they used to be: Missing a Control group

Reason: A control group helps in comparing the effectiveness and results with the experimental group, because this group is controlled by the experimenter where no intervention or treatment of independent variable is given. Here, in the study, a control group is missing to compare the effectiveness of the scream therapy.

2) A researcher wanted to determine whether a new antianxiety drug Streszac was effective. He tested a group of subjects who suffer from generalized anxiety disorder using a series of psychological tests. Then, subjects are randomly assigned to either an experimental group who receives the Streszac and a control group who does not. After 3 months of treatment, the participants who received Streszac show significantly less anxiety than the control group: Placebo effect

Reason: Placebo effect is an effect that makes the treatment effective not because of the drug or nature of treatment provided but because of the belief of the participant in the treatment. Here, the experimental group was given Streszac but not the control group. If the control group was also given some drug, then it could have been compared that whether the effect was due to streszac or due to placebo. But here, we will not get to know if the effect was due to the drug itself or was it a placebo effect. The experimental group could have shown less anxiety due to placebo effect and not due to streszac.

3) A researcher wants to discover if people can read her mind. Her procedure is as follows: she carefully shuffles a deck of cards and then looks at the top card. She nods to the subject across from her and tells him or her to try to guess what suit it is. The odds are that the subject should guess only 25% correctly, but the subjects consistently do much better than that: Demand characteristics

Reason: Demand characteristics are the characteristics that tend to influence the results of an experiment because the experimenter's expectations are conveyed to the participants and they try to behave according to the experimenter's demands or expectations. Here, the experimenter is expecting the participants to guess the card correctly. Therefore, they are performing even better because they believe that they are expected to do so.

4) A psychologist wants to determine whether love and affection will make an adult monkey more active. He starts off with a group of 12 monkeys and randomly assigns them to either the experimental group or the control group. Every day, the psychologist plays with the animals in the experimental group but not with the ones in the control group. At the same time, he is careful to be sure that both groups get enough food and water.  After one month, he carefully measures the activity level of all of the animals and discovers that indeed the experimental animals are more active. Based on this result he concludes that love and affection caused animals to become more active: Extraneous variables present

Reason: An extraneous variable is a variable which might influence the dependent variable and is not an independent variable. This simply means that it is an extra variable that might have the potential to alter the results. For example, here, the high activity level of the monkeys in the experimental group can be due to remaining active throughout the month and not just due to love and affection. Whereas, the monkeys in the control group did not get to play or become active during that one month period, hence might not be active due to that.