Applications Exercisesresearch in Psych, 4E: Study Guide, Chapter 66-1

Applications ExercisesResearch in Psych, 4e: Study Guide, Chapter 66-1

Between or Within?

For each of the following, first identify the independent and dependent variables (in general terms). Then decide whether it would be more appropriate to use a between-subjects design or a within-subjects design, given the limited information presented for each study. Explain your choice. If you think a between-subjects design is called for, decide whether equivalent groups could be formed and if so, the best way to form them (random assignment or matching). If you think matching is needed, identify a matching variable. If you think a within-subjects design is called for, then make a recommendation about the type of counterbalancing to use.

1. In study of eyewitness memory, a researcher wishes to determine whether the accuracy of eyewitness memory can be influenced by the level of stress an eyewitness experiences.

2.In a cross-cultural study of prejudice, a researcher wished to know whether prejudices would develop earlier in life for Western (e.g., United States) or Eastern (e.g., China) cultures.

3.In a study on the sense of touch, blindfolded participants had to judge whether the apparatus touching their skin had two points or one. The researcher wished to determine if different areas of the skin (e.g., palm of the hand vs. small of the back) were differentially sensitive.

4.A cognitive psychologist interested in the development of memory studies (annually) the short-term memory capacity of the same 20 children as they grow from age 4 through age 8.

5.To determine whether there is a universality to facial expressions of emotions, a researcher prepares pictures of people from three different cultures, each showing the same variety of expressions (e.g., smile, scowl). On a given trial of the study, a participant looks at a photo, then chooses a matching emotion from a list of ten different emotions.

6.A psychologist interested in maze wishes to learn whether learning is faster when the maze is run 10 times a day, once a day for ten 10 days, or twice a day for five days.

Answers

1.IV = stress levels experienced

DV = eyewitness accuracy

Between-subjects design: presumably there will be at least two levels of stress and a participant will witness some kind of event unexpectedly then have to report on it; having done this once, it would be impractical to have the same person do it again when experiencing a different level of stress.

Equivalent groups: use random assignment if there is a large participant pool; otherwise, it might be wise to match the groups on their characteristic levels of anxiety, as determined by a test for anxiety tendencies.

2.IVs = culture and age

DV = level of prejudice

Between-subjects design: both independent variables are subject variables, thereby dictating a between-subjects approach; because the groups are inherently nonequivalent

Equivalent groups: neither random assignment nor matching could be used to create equivalent groups (you will learn in Chapter 7, however, that a form of matching is often used in designs like this to reduce the degree of nonequivalency)

3. IV = area of the skin

DV = judgment (one or two points)

Within-subjects design: like most research in sensation and perception, this is a situation in which participating in one condition (palm being tested) won’t have much of an effect on being tested in the other condition (back), as long as counterbalancing is used properly; also, in this type of study it is important for each person to make a comparison between his or her palm and back.

Counterbalancing: each position would probably be tested several times; either reverse counterbalancing or block randomization could be used; because there are only two positions being tested, another option would be to simply alternate from one to another.

4. IV = age

DV = STM capacity

Within-subjects design: by studying the same children every year, this is a longitudinal design.

Counterbalancing: not relevant of course (unless the researcher has a time machine that would enable him or her to test a child first at age 8 then at age 6, etc.)

5. IV = cultures represented in the photos

DV = accuracy of judging the emotion

Within-subjects: it would be good to see if the same participant could accurately judge a particular emotion (e.g. sadness) when displayed in three different cultures.

Counterbalancing: let’s say there are 21 photos - seven emotions shown for each of the three cultures; if each participant is tested once, partial counterbalancing would be used, probably by giving each participant a random sequence of the photos; if testing occurred more than once per participant, block randomization would probably be used (several consecutive random sequences of the 21 faces)

6. IV = maze running schedule

DV = learning

Between-subjects: once a rat has been tested in one of the three conditions, that rat “knows” the maze; rats should begin each of the three conditions in a state of maze ignorance.

Equivalent groups: white rats are very similar genetically and cheap to buy or raise; random assignment will be fine here.

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