Title: Psychology 7
1Psychology 7 Experimental Psychology
Complex Designs
Professor Gallagher and his controversial
technique of simultaneously confronting the fear
of heights, snakes, and the dark.
2Mean 78
Approx. Curve 86-100 A 79-85 B 63-78 C 50-62 D lt
50 F
3Factors and Levels
- Factor is another term for independent variable
- Experiment Randomly assign subjects to drink
coffee or drink de-caf - One factor whether or not drink coffee
- Levels refer to the different conditions within a
factor - 2 levels in the coffee example regular coffee
vs. de-caf - Experiment with a 3rd group drink caffeinated
soda would have 3 levels but still one factor
4One Factor Designs with gt 2 Levels
- 2 basic reasons for having gt 2 levels
- Need more than 2 to detect curvilinear or complex
relationships between variables - May want multiple control groups/be interested in
multiple conditions
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1
2
3
Yerkes-Dodson Law
5Bandura Study of Imitative Aggression
- Children (3-5 yrs) assigned to 1 of 3 conditions
- Observe aggressive adult beat up Bobo doll
- Observe nonaggressive adult not beat up Bobo doll
- No exposure to any adult model
- Matched Pairs Design Children were enrolled in
Stanford Universitys Nursery School - Rated by teachers for degree of aggressiveness
- Matched for aggressiveness before being randomly
assigned to conditions - Hypotheses (1) Kids exposed to aggressive
models would perform more aggression than those
in other 2 groups, (2) Exposure to nonaggressive
model would inhibit aggression (prediction no
exposure kids gt aggression than nonaggressive
condition)
6- Dependent variable measured in a different room
in the absence of the adult models - Prior to the test for imitation, however, all
subjects were subjected to mild aggression
arousal to insure that they were under some
degree of instigation to aggression. - Experimenter brought kids into room with
attractive toys and after letting them get
engaged with them ( 2 min.), remarked that
these were her very best toys, that she did not
let just anyone play with them, and that she had
decided to reserve these toys for the other
children. - Modeling apparently doesnt work without this
added instigation - Observers counted of aggressive acts in
specific categories behind one-way mirror over 20
minute interval
7Results
Bandura, Ross, Ross (1961)
8Factorial Designs
Factorial designs involve gt 1 independent
variable or factor All levels of each
independent variable are combined with all levels
of the other independent variables
Example Balanced Placebo Design Study
Factor 1 Level 1 Level 2 Factor 2 Level
1 Level 2
- Alcohol expectations
- Expect vodka
- Expect tonic
- Alcohol intake
- Drank vodka
- Drank tonic
9Alcohol Study
Expectations
Alcohol
No alcohol
Tonic
Intake
Vodka
...a 2(rows) x 2 (columns) design
10Multiplicative Notation
A 3 x 4 factorial design
2 Factors with 3 and 4 levels
12 cells total (3 x 4)
A 2 x 2 x 2 factorial design How many
factors? How many cells?
11Alcohol Example
Expectations
Alcohol
No alcohol
Group 1 average
Group 3 average
Tonic
Group 2 average
Group 4 average
Intake
Vodka
Usually, averages are in the cells
12Main Effects
- Main effects are the effects of each independent
variable considered separately - E.g., does actually drinking vodka produce higher
levels of shock delivered to a learner than
drinking tonic? (main effect of alcohol intake) - Main effects compare the effects of levels within
a factor averaged across all levels of the other
factors - The number of possible main effects is equal to
the number of factors
13Main Effects in Baseball
- Right-handed (RH) vs. Left-handed (LH) batters
face either a Right-handed (RH) or Left-Handed
pitcher
A main effect looks at the effect of 1 factor
while ignoring the others
Pitcher
RH
LH
Main Effect of Handedness LH gt RH
RH
Batter
LH
14Interaction Effects
- When the effect of one independent variable
depends on the level of another independent
variable - Cannot fully understand the influence of one
independent variable without reference to another
independent variable
15Interaction Effects in Baseball
- External Validity Extent to which results of a
study would be found with different participants
or in a different setting/situation - Interactions related to external validity Does
an independent variable have the same effect in a
different situation or with different
participants? (with the different situation
represented by another factor).
Study 1
Study 2
RH
RH
Batter
Batter
LH
LH
Right-handed Pitcher
Left-handed Pitcher
16Main Effects in American Idol
Yeah!! Go Corey!
Type of Song
Overall Avg.
Love Song
Rock Song
150
Main Effect of Sex F gt M
Male
Sex of Singer
Female
250
DV of votes (in thousands)
17Graphing Results of Factorial Designs
For Main Effects Compute the averages for each
condition and plot as bar graphs Which is larger?
18Graphing Results of Factorial Designs
For Interaction Effects Plot all of the data as
line graphs. Nonparallel lines indicate an
interaction.
Pitcher
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21Alcohol Study in Factorial Notation
Expectation
Alcohol
No Alcohol
Alcohol
4.3
Actually Get
4.2
No Alcohol
5.05
3.45
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23Main Effects in Alcohol Study
24Simple Main Effects
- Simple main effects examine the effects of one
factor at one level of another factor - E.g., do right-handed batters have higher batting
averages than left-handed batters against
left-handed pitchers? - Question is isolated to left-handed pitchers (one
level of the pitcher handedness factor)
25Simple Main Effects
Simple Main Effects of Batter Handedness at 2
levels of pitcher handedness
Pitcher Factor Level1
Pitcher Factor Level 2
RH
RH
Batter
Batter
LH
LH
Right-handed Pitcher
Left-handed Pitcher
26Simple Main Effects in American Idol
Yeah!! Go Corey!
Type of Song
Overall Avg.
Love Song
Rock Song
150
Main Effect of Sex F gt M
Male
Sex of Singer
Female
250
DV of votes (in thousands)
27Graphing Results of Factorial Designs
For Interaction Effects Plot all of the data as
line graphs. Nonparallel lines indicate an
interaction.