Bias in Political Communication
Experiments
Jamie Druckman
&
Thomas Leeper
Dept. of Political Science
Northwestern University
1
Mass Communication Effects
•
Political communication research is “one of the most notable
embarrassments of modern social science” (Bartels 1993).
•
“Compelling concepts that have had a major impact in
political science and communications scholarship” (Iyengar
2010).
•
Key method behind progress  experiments (survey & lab).
•
Randomly expose some respondents to one message
(e.g., hate group rally as a free speech issue)….
•
…others to another message (e.g. rally as a public
safety issue), and…
•
…measure the effect (e.g., support for the rally).
2
Mass Communication Effects
•
But what about time? What happens before and after the
experiment? Does it matter?
•
Claim: Ignoring what happens prior to the experiment
(i.e., “pre-treatment”) has produced a bias portrait of
communication effects that may:
•
overstate the malleability of the public (see Barabas
and Jerit 2010).
•
miss the identification of potentially two groups of
citizens: malleably reactive and dogmatists.
•
contradict much macro opinion formation research.
3
Outline
•
•
•
•
Psychology of pre-treatment effects
•
Framing effects and defining pre-treatment
•
Attitude strength
•
Hypotheses  conditions when pre-treatment effects occur
Laboratory experiment
•
Manipulates pre-treatment environment and attitude strength
(via processing mode)
•
Survey experiment
Election exit poll experimental survey
•
Measures pre-treatment environment and attitude strength
correlate
•
Survey experiment
Conclusion
4
Framing
•
Framing effects  In the course of describing an issue, a
speaker’s emphasis on a subset of relevant considerations
causes individuals to focus on these considerations when
constructing their opinions.
•
Example: Politicians, media frame hate group rally request as a:
•
•
free speech issue  citizens focus on speech
considerations  citizens support right to rally
•
public safety issue  citizens focus on safety
considerations  citizens oppose right to rally
Experiments  random exposure to framed communication as a
news article or in question wording (e.g., on a survey).
5
Framing
•
Many other examples:
•
campaign finance (free speech or corruption?)
•
abortion (rights of mother or rights of unborn child?)
•
gun control (right to bear arms or public safety?)
•
affirmative action (reverse discrimin. or remedial action?)
•
welfare policy (humanitarianism or overspending?)
•
social security (individualism or shared security?)
•
elections (economy or foreign affairs?)
•
A Central Means of Elite Influence on Public Opinion.
•
These effects ≠ valence framing effects (Tversky and
Kahneman)
6
Pre-treatment
•
Pre-treatment environment  context prior to exposing
experimental participants to the stimulus (frame).
•
Pre-treatment effect  aspect of the prior context affects
responses to the stimulus (frame).
•
Example:
•
Prior to the hate group rally experiment, respondents
view news coverage using the free speech frame and
become more supportive….
•
…another free speech exposure in the experiment
does not further move opinion.
•
Mistaken conclusion of no effect.
•
Possibly don’t/can’t publish the experiment!
7
Pre-treatment
•
“Experimenters implicitly assume…that respondents enter the
survey as clean slates… [despite the fact that] there is
inevitably some possibility that respondents enter the
experiment having already participated in a similar experiment,
albeit one occurring in the real world” (Gaines et al. 2007).
8
Conditions for Pre-treatment Effect
•
Exposure/Attention  Absent exposure and attention to
information, there is no “pre-treatment.”
•
Durable Influence 
•
Absent initial influence, there is no “effect.”
•
Absent durability, the initial influence will not impact
experimental reactions (i.e., the effect must sustain until
the time of the experiment).
•
Depends on time between pre-treat and experiment.
•
Depends on nature of the attitude formed in response
to the effect
Attitude strength
9
Attitude Strength
•
Attitude Strength  attitudes that persist and resist change.
•
•
Stems from attitude features (e.g., extremity) and the
formation/updating process.
Two dynamics that affect attitude strength:
1. Processing Mode
2. Need to Evaluate
10
Attitude Processing Mode
•
Individuals form/update attitudes in relatively more memorybased or online fashion (Haste & Parke 1986, Lodge et al.).
•
On-line (OL):
• immediately integrate information (i.e., frames at time t
in the pre-treatment environment) into an overall
evaluative summary,
• store it, and
• recall it when needed (i.e., at t+1, in an experiment).
• Thus, impact of earlier information sustains  attitudes
formed at time t pre-treatment are stronger (i.e.,
durable, resistant change in time t experiment).
11
Attitude Processing Mode
•
Memory-based (MB): store information (frames) in
memory, do not evaluate it until asked for an attitude at
which point retrieve what can be recalled and integrate.
• May not recall items from distant past.
• Thus, impact of earlier information does not sustain 
attitudes formed at time t pre-treatment are weak and
information may be forgotten.
•
Pre-treatment effects are more likely to occur among OL
processors since earlier effects sustain and generate resistance
to later influence (i.e., in the experiment).
12
Need to Evaluate
•
Need to Evaluate (NE)  “individual propensity to engage in
evaluation.”
• More likely to assess and retain information (once
exposed). Generate stronger attitudes, similar to OL
processing.
• Thus, impact of earlier information sustains  attitudes
formed at time t pre-treatment are stronger (i.e.,
durable, resistant to change in time t experiment).
•
Pre-treatment effects are more likely to occur among high NE
individuals since earlier effects sustain and generate resistance
to later influence (i.e., in the experiment).
13
Hypothesis
Pre-treatment effects (e.g., leading to no experimental stimulus
effect) will be more likely to occur when individuals are:
• exposed and attentive to earlier communications similar
to the experimental stimuli; and
• form/update their attitudes in ways that promote
strength. This occurs among on-line processors and high
NEs.
Motivated Reasoning Corollary
•
Motivated reasoning  reject information that is
inconsistent with prior opinions.
•
Those with stronger attitudes are more likely to engage in
motivated reasoning.
•
Those with strong attitudes (i.e., OL, high NE) not only will
not be influenced by a “repeated communication” but may
reject contrary communication.
14
Experiment 1
•
Laboratory experiment with 744 participants (mostly
students), Spring 2010.
•
Two Issues (both salient but not currently intensely
debated)
•
Support for the Patriot Act (increases law enforcement
power to combat terrorism) (measured on 7-point
scale).
•
Support for a state owned gambling casino (measured
on 7-point scale).
15
Experiment 1
•
Pro/Con Strong Frames (in news articles):
•
Patriot Act:
•
Pro  Protection from terrorism
•
Con  Violation of Civil Liberties
•
Casino:
•
Pro  Economic benefits (e.g., tax relief)
•
Con  Social costs (e.g., addiction, debt)
16
Experiment 1
•
Manipulated OL or MB processing mode (using
conventional psychological approach)
•
OL  respondents instructed to evaluate articles
for their impact in increasing or decreasing
support. Told they will later report opinions.
•
MB  respondents instructed to evaluate articles
for their “dynamic” nature (i.e., use of actionoriented words).
17
Experiment 1
Procedure  Four waves, 5 days apart.
1. Background survey, assigned to condition that
varied: (a) pre-treatment environment, (b)
processing mode, (c) survey frame, AND
--received two relevant pre-treatment frames, along
with processing manipulation.
2. Received pre-treatment frame articles, along with
processing manipulation.
3. Same as #2.
4. Received survey question using no, con, or pro
frame.
 virtually no attrition because compensation contingent
on full completion.
 virtually no coverage of these issues during the
experiment or several months prior.
18
Conditions
No Survey
Frame
No PrePretreatment
Pro Survey
Frame
(Economic/
Terrorism)
No Processing Manipulation
(condition 1) (2)
N = 51
N = 44
On-Line Processing Manipulation
(4)
(5)
N = 65
N = 44
Con Survey
Frame
(Social
Costs/Civil
Liberties)
(3)
N = 35
(6)
Pro PreN = 44
Pretreatment
(Economic/
Terrorism)
(7)
(8)
(9)
Con
N = 46
N = 47
N = 46
Pretreatment
(Social Costs/
Civil Liberties)
Memory Based Processing Manipulation
(10)
(11)
(12)
Pro
N = 53
N = 52
N = 70
Pretreatment
(Economic/
Terrorism)
(13)
(14)
(15)
Con
N = 46
N = 55
N = 46
Pretreatment
(Social Costs/
Civil Liberties)
Expect survey frames will have scant effects in the OL conditions,
but will impact MB processors (and the no-pre-treated individuals).
19
Patriot Act Survey Frames
•
Control  “The Patriot Act was enacted in the weeks
after September 11, 2001, to strengthen law
enforcement powers and technology. What do you
think—do you oppose or support the Patriot Act? Choose
one number on the following 7-point scale.”
•
Con  “…technology. Under the Patriot Act, the
government has access to citizens’ confidential
information from telephone and e-mail communications.
As a result, it has sparked numerous controversies and
been criticized for weakening the protection of citizens’
civil liberties…”
•
Pro “…technology. Under the Patriot Act, the
government has more resources for counterterrorism,
surveillance, border protection, and other security
policies. As a result, it enables security to identify
terrorist plots on American soil and to prevent attacks
before they occur…”
20
Casino Survey Frames
•
Control  “A proposal is being considered for the Illinois
state government to operate a land-based gambling casino.
What do you think—do you oppose or support the proposal
for a state-run gambling casino? Choose one number on the
following 7-point scale.”
•
Con  “…Some say that a state-run casino will have severe
social costs, such as addiction and debt..”
•
Pro  “…Some say that the revenue from the casino would
provide tax relief and help to fund education…”
21
Results
•
Simple mean comparisons, robust to controls.
•
Similar results for two issues; here present Patriot Act results.
•
Gradual disaggregation of conditions…
22
Patriot Act Results
Patriot Act Support By Survey Frame
(across pre-treatment and processing conditions)
Average Patriot Act Support
5
Con
Control
4
Pro
3.76*
(1.90; 205)
3.53
(1.66; 233)
2.99***
(1.66; 211)
3
2
(conditions 3,6,9,12,15)
All Con Frame
(***p<.01; **p<.05 ; *p<.1 for one-tailed
tests, versus "All No Frame")
(1,4,7,10,13)
All No Frame
(2,5,8,11,14)
All Pro Frame
Survey Frame
• Strong survey framing effect.
23
Patriot Act Results
Patriot Act Support By Processing Mode and Survey Frame
(across pre-treatment conditions)
5
Average Patriot Act Support
Nonmanipulated
OL
MB
4.03**
(1.80; 39)
3.88+
(2.00; 91)
4
3.58
(1.67; 102)
3.39
(1.58; 46)
3.36
(1.69; 80)
3.55
(1.69; 85)
3.48
(1.80; 75)
3
2.78***
(1.67; 99)
2.69**
(1.38; 32)
2
(3)
(1)
(2)
NM Con
NM No
NM Pro
Frame
Frame
Frame
(***p<.01; **p<.05 ; *p<.1; +p<.13;for one-tailed tests,
versus "No Frame" within each processing mode)
(6,9)
OL Con
Frame
(4,7)
OL No
Frame
(5,8)
OL Pro
Frame
(12,15)
MB Con
Frame
(10,13)
MB No
Frame
(11,14)
MB Pro
Frame
Survey Frame
• Strong survey framing effects for non-manipulated and MB.
• NO SURVEY FRAMING effects for OL.
• Effects apparent in merged data stem entirely from nonmanipulated and MBs.
24
Patriot Act Results
Patriot Act Support By Processing Mode and Survey Frame
(across pre-treatment conditions)
5
Average Patriot Act Support
Nonmanipulated
OL
MB
4.03**
(1.80; 39)
3.88+
(2.00; 91)
4
3.58
(1.67; 102)
3.39
(1.58; 46)
3.36
(1.69; 80)
3.55
(1.69; 85)
3.48
(1.80; 75)
3
2.78***
(1.67; 99)
2.69**
(1.38; 32)
2
(3)
(1)
(2)
NM Con
NM No
NM Pro
Frame
Frame
Frame
(***p<.01; **p<.05 ; *p<.1; +p<.13;for one-tailed tests,
versus "No Frame" within each processing mode)
(6,9)
OL Con
Frame
(4,7)
OL No
Frame
(5,8)
OL Pro
Frame
(12,15)
MB Con
Frame
(10,13)
MB No
Frame
(11,14)
MB Pro
Frame
Survey Frame
• Non-manipulated = MB.
• Aggregate results may stem from particular sub-groups.
• Aggregate effect sizes underestimate impact on affected groups
25
(e.g., MB moved .10 more than merged data from pro frame).
Patriot Act Results
Patriot Act Support For OL Processors
By Pre-Treatment Exposure and Survey Frame
5
Average Patriot Act Support
Pro Pre-treat
Con Pre-treat
4.17**
(1.56; 36)
3.84+
(1.74; 37)
4
3.90**
(1.62; 61)
3.39
(1.58; 46)
2.95*
(1.54; 43)
3
3.10
(1.66; 41)
2.85*
(1.80; 39)
2
(1)
(6) OL
NM No
Pro PT
Frame
Con Frame
(***p<.01; **p<.05 ; *p<.1; +p<.13; for one-tailed
tests, versus "NM No Frame")
(4) OL
Pro PT
No Frame
(5) OL
Pro PT
Pro Frame
(9) OL
Con PT
Con Frame
(7) OL
Con PT
No Frame
(8) OL
Con PT
Pro Frame
Survey Frame
• Non-effect among OL is illusionary!
26
Patriot Act Results
Patriot Act Support For OL Processors
By Pre-Treatment Exposure and Survey Frame
5
Average Patriot Act Support
Pro Pre-treat
Con Pre-treat
4.17**
(1.56; 36)
3.84+
(1.74; 37)
4
3.90**
(1.62; 61)
3.39
(1.58; 46)
2.95*
(1.54; 43)
3
3.10
(1.66; 41)
2.85*
(1.80; 39)
2
(1)
(6) OL
NM No
Pro PT
Frame
Con Frame
(***p<.01; **p<.05 ; *p<.1; +p<.13; for one-tailed
tests, versus "NM No Frame")
(4) OL
Pro PT
No Frame
(5) OL
Pro PT
Pro Frame
(9) OL
Con PT
Con Frame
(7) OL
Con PT
No Frame
(8) OL
Con PT
Pro Frame
Survey Frame
• Pre-treatment effects:
• Pro pre-treatment frames significantly increased support,
regardless of survey frame.
• Con pre-treatment frames significantly decreased support,
regardless of survey frame.
• Repeated frame in survey had minimal impact, and contrary
frame was rejected (motivated reasoning).
27
Patriot Act Results
Patriot Act Support For MB Processors
By Pre-Treatment Exposure and Survey Frame
5
Average Patriot Act Support
Pro Pre-treat
Con Pre-treat
3.93*
(2.26; 44)
4
3.83*
(1.76; 47)
3.66
(1.70; 44)
3.44
(1.70; 41)
3.39
(1.58: 46)
3
2.87*
1.83; 37)
2.73**
(1.58; 62)
2
(1)
(12) MB
NM No
Pro PT
Frame
Con Frame
(***p<.01; **p<.05 ; *p<.1 for one-tailed tests,
versus "NM No Frame")
(10) MB
Pro PT
No Frame
(11) MB
Pro PT
Pro Frame
(15) MB
Con PT
Con Frame
(13) MB
Con PT
No Frame
(14) MB
Con PT
Pro Frame
Survey Frame
• No evidence of pre-treatment effects for MB processors.
• Significant survey framing effect in each case, regardless of the
pre-treatment environment.
28
Patriot Act Results: Belief Importance
Survey Frame /
Consideration
OL Processors in
contrary pre-treat
environment and
received survey
frame
All Other
Respondents
OL Processors in
contrary pre-treat
environment but did
not receive survey
frame
Patriot Act Con: Civil 4.49
Liberties
(1.71; 37)
5.55***
(1.46; 612)
4.94*
(1.56; 98)
Patriot Act Con:
Terrorism
5.15***
(1.51; 609)
4.55**
(1.76; 85)
3.97
(1.87; 39)
***p.01; **p.05; *p.10 for one-tailed tests, relative to OL Processors in contrary pre-treat environment and received survey frame condition.
• OL processors who received a survey frame contrary to their pretreatment environment, viewed that argument as significantly less
important  evidence of motivated reasoning (rejection of contrary
information).
• Are these types of effects evident outside of manufactured lab
setting?
29
Experiment 2
•
Exit poll experimental survey that measures pre-treatment
environment and attitude strength correlate, with 338
respondents.
•
Issue: Support for a proposed state owned gambling casino
during the 2006 IL Gubernatorial campaign (measured on a
7-point scale).
•
Tracked media (i.e., pre-treatment) environment:
•
Pro-casino frames: economic benefits,
(entertainment).
•
Con-casino frames: social costs (corruption,
morality).
•
Exit poll survey experiment.
•
Measure attention and likelihood of enduring opinion (via
Need to Evaluate item).
30
The Campaign
(pre-treatment environment)
•
2006 IL Gubernatorial pitting Blagojevich (D) vs. Topinka (R).
•
Aug. 23: Topinka proposes state owned casino to raise
revenue (t = 1).
•
Aug. 24: Chicago Tribune Comment: Topinka is “framing the
contest… just as it needs to be framed: How can a grossly
overcommitted state gov. bend financial trend lines that point
inexorably toward ruin.”
•
Sept. 9: Corruption accusation against Blagojevich of taking a
personal payoff for a state job.
•
Others follow!
•
Nov. 7: Election Day (t = n).
•
Coded campaign coverage in the Chicago Tribune from t = 1
(Aug. 23rd) to t = n (Election Day).
•
Most prominent issues: economy (budget) & corruption.
31
The Campaign
Percentage of Total
Coverage
Issue Emphasis
60%
50%
40%
30%
20%
10%
50%
35%
Budget
32%
Casino
15%
14%
0%
8/24-9/9
Corruption
14%
3%
5%
2%
9/10-9/30
10/1-11/6
Time Period
•
Early campaign discussions of the casino were framed in terms of
economic benefits > 75% of the time.
32
Predictions
•
Attentive high NEs will be significantly more likely to form and
maintain casino opinions upon exposure to the early campaign
information (e.g., with economic frame focus).

•
Less susceptible to the economic frame later (already
influenced) and the social costs frame (reject it).
•
More supportive of the casino proposal.
33
Exit Poll
•
Election Day exit poll (t = n).
•
Random sample of polling stations in north Cook County. ($5 for
participation).
•
Measured NE (i.e., 1 item measure) & Campaign Attention (i.e.,
newspaper reading during campaign period), etc.
•
•
Attentive voters  greater knowledge, discussion, interest
in politics.
•
Attentive / High NE voters  above median on NE and
attention (n = 111).
Four relevant experimental conditions:
•
No frame – asked extent of casino support.
•
Economic frame  pro casino.
•
Social costs of gambling  con casino.
34
•
Economic-Social costs  dual frame.
NE Measures
Some people have opinions about almost everything; other people
have opinions about just some things; and still other people have
very few opinions. What about you? Would you say you have
opinions about almost everything, about many things, about some
things, or about very few things?
almost
everything
many
things
some
things
very few
things
Compared to the average person, do you have a lot fewer opinions
about whether things are good or bad, somewhat fewer opinions,
about the same number of opinions, somewhat more opinions, or a
lot more opinions?
a lot fewer somewhat
opinions
fewer opinions
about the
same
somewhat
more opinions
a lot more
opinions
Some people say that it is important to have definite opinions about
lots of things, while other people think that it is better to remain
neutral on most issues. What about you? Do you think it is better to
have definite opinions about lots of things or to remain neutral on
most issues?
definite
opinions
remain
neutral
35
Results
Exit Poll Casino Support By Conditon and Attention/NE
5
4.58***
(1.75; 69)
Average Casino Support
4.20***
(1.86; 109)
All
Non Att/Low NE
Att/High NE
4
3.57
(1.86; 37)
3.09
(1.89; 117)
3
2.91
(2.01; 55)
3.36
(2.23; 39)
3.30
(1.95; 20)
2.93
(1.87; 15)
2.87
(1.72; 71)
2.52
(2.05; 31)
2.04***
(1.28; 57)
2
1.71***
(.81; 42)
1
All
Pro
Frame
All
No
Frame
All
Both
Frames
All
Con
Frame
(***p<.01; **p<.05 ; *p<.1 for one-tailed tests, versus
"No Frame" within each group)
Non Att./ Non Att./ Non Att./ Non Att./
Low NE Low NE Low NE Low NE
Pro
No
Both
Con
Frame
Frame
Frames
Frame
Att./
Att./
Att./
Att./
High NE High NE High NE High NE
Pro
No
Both
Con
Frame
Frame
Frames
Frame
Group and Survey Frame
• All = Large survey framing effect.
• Non-attentive/Low NE  large survey framing effect.
36
Results
Exit Poll Casino Support By Conditon and Attention/NE
5
4.58***
(1.75; 69)
Average Casino Support
4.20***
(1.86; 109)
All
Non Att/Low NE
Att/High NE
4
3.57
(1.86; 37)
3.09
(1.89; 117)
3
2.91
(2.01; 55)
3.36
(2.23; 39)
3.30
(1.95; 20)
2.93
(1.87; 15)
2.87
(1.72; 71)
2.52
(2.05; 31)
2.04***
(1.28; 57)
2
1.71***
(.81; 42)
1
All
Pro
Frame
All
No
Frame
All
Both
Frames
All
Con
Frame
(***p<.01; **p<.05 ; *p<.1 for one-tailed tests, versus
"No Frame" within each group)
Non Att./ Non Att./ Non Att./ Non Att./
Low NE Low NE Low NE Low NE
Pro
No
Both
Con
Frame
Frame
Frames
Frame
Att./
Att./
Att./
Att./
High NE High NE High NE High NE
Pro
No
Both
Con
Frame
Frame
Frames
Frame
Group and Survey Frame
• Attentive/High NE  NO survey framing effect. Significantly
higher support across conditions.
• Pre-treatment effects  No experimental effects but was
earlier influence.
• Other evidence suggests motivated reasoning for those
receiving social costs frame.
37
Summary
•
•
The existence of an experimental effect can be misleading as it:
•
may stem from a subgroup that formed weak attitudes
(e.g., MB) on the issue (Gaines et al. 2007, Barabas and
Jerit 2010), and
•
may understate the effect size among those individuals.
The non-existence of an experimental effect can be misleading
as it:
•
may stem from a large number of individuals forming strong
attitudes (e.g., OL) in response to communications prior to
the experiment.
•
Such individuals were limited in our studies, but may be
pervasive in other contexts.
• Hillygus and Jackman (2003)  conventional effects >
debate effects.
38
Summary
•
Given publication biases (e.g., Gerber et al. 2010),
experimental studies may over-state the existence of
effects, and thus:
•
The mass public, on average, is less malleable and holds
more stable opinions than would be suggested by the
aggregation of experimental results.
•
The mass public may be bi-modal  malleably reactive
and dogmatically invulnerable.
•
Caveat  those who formed strong attitudes were
affected by earlier stimuli.
39
Summary
•
Varying levels of stability in macro and micro-level
studies of opinion may stem, in part, from different
issue foci:
•
Macro studies  longstanding salient issues that
generate stronger attitudes (e.g., Gallup’s most
important problem surveys)
•
Micro over-time studies  relatively novel and
specific issues (e.g., ballot proposition, new
candidate, regulation of hog farms, campaign
finance).
40
Conclusions
•
Opinions are not fixed in time. Time dynamics need study 
priors, pre-treatment, durability. and post-treatment effects.
•
Failure to account for these dynamics  inferential errors.
•
Precise effects depend on attitude strength.
•
What should public opinion researchers do?
•
Define time period of study (as a unit of analysis).
•
If goal is to evaluate impact of an argument, test for pretreatment effects.
• Identify prior rhetorical context.
• Test with distinct populations or times.
•
Develop theories of over-time effects
41
• END
42
Casino Results
Casino Support By Survey Frame
(across pre-treatment and processing conditions)
5
Average Casino Support
4.32***
(1.55; 205)
3.92
(1.52; 234)
4
3.51***
(stdev=1.54; N=210)
3
2
(conditions 3,6,9,12,15)
All Con Frame
(***p<.01; **p<.05 ; *p<.1 for one-tailed
tests, versus "All No Frame")
(1,4,7,10,13)
All No Frame
(2,5,8,11,14)
All Pro Frame
Survey Frame
43
Casino Results
Casino Support By Processing Mode and Survey Frame
(across pre-treatment conditions)
5
4.56***
(1.48: 91)
Average Casino Support
4.51**
(1.73; 39)
3.96
(1.40; 46)
4
3.81
(1.49; 79)
3.84
(1.54; 103)
4.01
(1.58; 85)
3.93
(1.48; 75)
3.40***
(1.54; 99)
3.06***
(1.59; 32)
3
2
(3)
NM Con
Frame
(1)
NM No
Frame
(2)
NM Pro
Frame
(***p<.01; **p<.05 ; *p<.1 for one-tailed tests,
versus "No Frame" within each processing mode)
(6,9)
OL Con
Frame
(4,7)
OL No
Frame
(5,8)
OL Pro
Frame
(12,15)
MB Con
Frame
(10,13)
MB No
Frame
(11,14)
MB Pro
Frame
Survey Frame
44
Casino Results
Casino Support For OL Processors
By Pre-Treatment Exposure and Survey Frame
5
4.78***
(1.01; 36)
4.47**
(1.21; 36)
Average Casino Support
4.26+
(1.41; 61)
4
3.96
(1.40; 46)
3.26***
(1.48; 43)
3.21***
(1.52; 42)
3.15***
(1.42; 39)
3
2
(1)
NM No
Frame
(6) OL
Pro PT
Con Frame
(***p<.01; **p<.05 ; *p<.1; +p<.13; for one-tailed
tests, versus "NM No Frame")
(4) OL
Pro PT
No Frame
(5) OL
Pro PT
Pro Frame
(9) OL
Con PT
Con Frame
(7) OL
Con PT
No Frame
(8) OL
Con PT
Pro Frame
Survey Frame
45
Casino Results
Casino Support For MB Processors
By Pre-Treatment Exposure and Survey Frame
5
Average Casino Support
4.61**
(1.58; 44)
4
4.51**
(1.38; 47)
4.05
(1.49; 44)
3.96
(1.40; 46)
3.98
(1.68; 41)
3.58*
(1.47; 62)
3.11***
(1.63; 37)
3
2
(1)
NM No
Frame
(12) MB
Pro PT
Con Frame
(***p<.01; **p<.05 ; *p<.1 for one-tailed tests,
versus "NM No Frame")
(10) MB
Pro PT
No Frame
(11) MB
Pro PT
Pro Frame
(15) MB
Con PT
Con Frame
(13) MB
Con PT
No Frame
(14) MB
Con PT
Pro Frame
Survey Frame
46