When Contact Changes Minds: An Experiment on Transmission of Support for Gay Equality
Last registered on January 24, 2015

Pre-Trial

Trial Information
General Information
Title
When Contact Changes Minds: An Experiment on Transmission of Support for Gay Equality
RCT ID
AEARCTR-0000611
Initial registration date
January 24, 2015
Last updated
January 24, 2015 8:25 PM EST
Location(s)
Primary Investigator
Affiliation
UCLA
Other Primary Investigator(s)
Additional Trial Information
Status
Completed
Start date
2013-05-29
End date
2014-03-31
Secondary IDs
Abstract
Can a single conversation change minds on divisive social issues, such as
same-sex marriage? A randomized placebo-controlled trial assessed whether gay (N=22)
or straight (N=19) messengers were effective at encouraging voters (N=972) to support
same-sex marriage and whether attitude change persisted and spread to others in voters’
social networks. The results, measured by an unrelated panel survey, show that both
gay and straight canvassers produced large effects initially, but only gay canvassers’ effects
persisted in three-week, six-week, and nine-month follow-ups. We also find strong
evidence of within-household transmission of opinion change, but only in the wake of
conversations with gay canvassers. Contact with gay canvassers further caused substantial
change in ratings of gay men and lesbians more generally. These large, persistent,
and contagious effects are confirmed by a follow-up experiment. Contact with minorities
coupled with discussion of issues pertinent to them is capable of producing a cascade of
opinion change.
External Link(s)
Registration Citation
Citation
LaCour, Michael. 2015. "When Contact Changes Minds: An Experiment on Transmission of Support for Gay Equality." AEA RCT Registry. January 24. https://www.socialscienceregistry.org/trials/611/history/3433
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Experimental Details
Interventions
Intervention(s)
Registered voters who had previously been enrolled in an Internet panel survey were
contacted at their doorstep by canvassers. Random assignment determined whether contact was initiated
by a gay or straight canvasser and whether the canvasser discussed the subject of same-sex
marriage or recycling. Outcomes were assessed unobtrusively by online surveys conducted days,
weeks, and months afterward. Canvassers were coached to be polite and respectful at all times, to listen attentively
to voters when discussing either same-sex marriage or recycling, and to refrain from arguing with
voters. The
same-sex marriage script invited voters to share their experiences with marriage. This script was the
same for gay and straight canvassers, with one important exception. After establishing rapport with
the voter, midway through the conversation, gay canvassers revealed that they are gay or lesbian and
that they would like to get married but that the law prohibits same-sex marriage. Straight canvassers
instead described how their child, friend, or relative would like to get married but that the law prohibits
same-sex marriage. Voters were asked to share their thoughts on this dilemma. These doorstep
conversations lasted on average 22 minutes.
Intervention Start Date
2013-06-01
Intervention End Date
2013-06-02
Primary Outcomes
Primary Outcomes (end points)
Before canvassers went into the field, the study first gathered baseline
positions on a range of political attitudes for all participants using an ostensibly unrelated online
survey. The survey included 50 questions, as described in the Supplemental Online Materials (SOM).
The two questions concerning same-sex marriage and feelings about gay people were buried amid
a large number of items on unrelated topics so that respondents would not suspect any connection
between the survey and the canvassing visit. The panel survey included the two outcome measures in
every wave, but the overall content of the survey was kept fresh by randomly rotating new questions
in each wave. Another important feature of the design concerns blinding of canvassers and survey
respondents. Voters were unaware that the online survey was related to the canvassing effort, and
canvassers had no knowledge that voters were participants in an online survey. Finally, to prevent
housemates from completing each other’s surveys, extensive precautions were taken, including issuing distinct personal login instructions to take differently named surveys, tracking of distinct IP addresses
and session cookies, and sending invitations to take the survey during working hours (91% were in
fact completed at work), when housemates would be less likely to be together.
Primary Outcomes (explanation)
Survey Outcome Measures:
1. Support For Same-Sex Marriage: Wording and format followed the Cooperative Campaign
Analysis Project 2012 (Jackman et al 2012): “Do you favor or oppose allowing gays and lesbians
to marry legally?” Response options ranged from strongly oppose to strongly favor, forming
a five-point scale.
2. Ratings of Gays and Lesbians: Wording and format followed the Cooperative Campaign
Analysis Project 2012 (Jackman et al 2012): “We would like to get your feelings toward a
series of demographic groups. We will display the name of a group, and we would like you
to rate the group using a ‘feeling thermometer.’ Ratings between 50 degrees and 100 degrees
indicate that you feel favorable and warm toward the group. Ratings between 0 degrees and 50
degrees mean that you don’t feel favorable toward the group and that you don’t care too much
for that group. You would rate the group at the 50 degree mark if you don’t feel particularly
warm or cold toward the group. Your rating will appear at the end of the slider.”
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Registered voters who had previously been enrolled in an Internet panel survey were
contacted at their doorstep by canvassers. Random assignment determined whether contact was initiated
by a gay or straight canvasser and whether the canvasser discussed the subject of same-sex
marriage or recycling. Outcomes were assessed unobtrusively by online surveys conducted days,
weeks, and months afterward.
Experimental Design Details
Randomization Method
Households in which at least two registered voters completed the first
wave of the on-line panel survey (May 29-30, 2013) were randomly assigned to five experimental
conditions. Simple random assignment occurred at the household level to facilitate the analysis of
within-household spillovers discussed below. The first group was assigned to receive the same-sex
marriage script from a gay canvasser. The second group was assigned to receive the same-sex marriage
script from a straight canvasser. Groups three and four were encouraged to recycle household waste
by gay or straight canvassers, respectively; however, canvassers did not reveal their sexual orientation
when delivering the recycling script. The fifth group was a control group to which no canvassers were
assigned.
Randomization Unit
Simple random assignment occurred at the household level to facilitate the analysis of
within-household spillovers discussed below.
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
3532 unique households
Sample size: planned number of observations
9,507 panelists interviewed over 7 waves, consisting of 59,207 survey interviews (with survey attrition).
Sample size (or number of clusters) by treatment arms
1943 households (HH) control (no canvassing contact), 423 households same-sex marriage message by gay canvasser, 385 households same-sex marriage message by straight canvasser, 389 households placebo recycling message by gay canvassers, 392 households placebo recycling message by straight canvassers
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
UCLA institutional review board
IRB Approval Date
2013-05-07
IRB Approval Number
12-001750
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
Yes
Intervention Completion Date
June 01, 2013, 12:00 AM +00:00
Is data collection complete?
No
Data Publication
Data Publication
Is public data available?
Yes
Program Files
Program Files
Yes
Reports and Papers
Preliminary Reports
Relevant Papers
Abstract
Can a single conversation change minds on divisive social issues, such as same-sex marriage? A randomized placebo-controlled trial assessed whether gay (n = 22) or straight (n = 19) messengers were effective at encouraging voters (n = 972) to support same-sex marriage and whether attitude change persisted and spread to others in voters’ social networks. The results, measured by an unrelated panel survey, show that both gay and straight canvassers produced large effects initially, but only gay canvassers’ effects persisted in 3-week, 6-week, and 9-month follow-ups. We also find strong evidence of within-household transmission of opinion change, but only in the wake of conversations with gay canvassers. Contact with gay canvassers further caused substantial change in the ratings of gay men and lesbians more generally. These large, persistent, and contagious effects were confirmed by a follow-up experiment. Contact with minorities coupled with discussion of issues pertinent to them is capable of producing a cascade of opinion change.
Citation
LaCour, Michael J. & Donald P. Green. “When Contact Changes Minds: An Experiment on Transmission of Support For Gay Equality”, Science, 12 December 2014: 346 (6215), 1366-1369.