Applications Exercises Research in Psych, 5e: Study Guide, Chapter 6 6-1
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.
Applications Exercises Research in Psych, 5e: Study Guide, Chapter 6 6-2
5. To determine whether there is 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.
Applications Exercises Research in Psych, 5e: Study Guide, Chapter 6 6-3
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
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.