Supplemental Materials
The Negative Effects of Prejudice on Interpersonal Relationships Within Adolescent Peer
Groups
by V. P. Poteat et al., 2015, Developmental Psychology
http://dx.doi.org/10.1037/a0038914
Factor Analysis of Scales Comprising Positive and Negative Interaction Indices
We conducted an exploratory factor analysis using principal axis factoring with varimax rotation,
which showed that positive and negative interaction indices loaded on two distinct factors (Table
S1). This, in addition to the non-significant association between the factors, supported our
decision to treat the scores for positive and negative interactions separately.
Test of Non-Significant Variance across Grade Levels
In a three-level multilevel model (i.e., individuals within groups within grades) we tested for
variance in positive and negative peer interactions across grade levels. We used HLM 7.0 test
these null models. There was no significant variance at Level 3 (i.e., grade level) in positive
interactions, χ2 = 2.48, p > .50, or negative interactions, χ2 = 3.74, p = .29.
Models Excluding Students with Inconsistent Group Membership from Time 1 to Time 2
We tested our models excluding students without consistent group membership at Times 1 and 2.
Groups varied in positive interactions (Z = 2.63, p < .01; ICC = .16) and negative interactions (Z
= 2.62, p < .01; ICC = .12) at Time 1. Similarly, groups varied in positive interactions (Z = 2.46,
p < .01; ICC = .15) and negative interactions (Z = 3.02, p < .01; ICC = .17) at Time 2. Results
for the contextual effects models are in Table S2. The results were comparable to those in the
main text that included these students with the exception that group sexual orientation
composition was no longer a significant predictor of positive interactions, individual sexual
orientation and age became significant predictors of negative interactions, and group-level
aggression was no longer a significant predictor of negative interactions. Results for the
socialization models are in Table S3. These results were comparable to those in the main text
that included these students with the exception that individual sexual orientation became a
significant predictor of positive interactions, and individual prejudice was no longer a significant
predictor of negative interactions.
Models Including Students Identified as Isolates
At the instruction of a reviewer, we tested our models including students identified as isolates. In
these models, each isolate was treated as her or his own “group”. Groups varied in positive
interactions (Z = 2.79, p < .01; ICC = .16) and negative interactions (Z = 2.54, p < .01; ICC =
.11) at Time 1. Similarly, groups varied in positive interactions (Z = 2.31, p = .01; ICC = .11)
and negative interactions (Z = 3.17, p < .01; ICC = .20) at Time 2. Results for the contextual
effects models are in Table S4. Group-level sexual prejudice remained a significant predictor of
negative interactions. Results for the socialization models are in Table S5. Time 1 group-level
sexual prejudice no longer significantly predicted Time 2 negative interactions. Although we
present these results at the instruction of a reviewer, we stress caution in their interpretation.
There are several reasons that this approach is not addressing the same research questions posed
in our main paper and that it is not in keeping with the theory on which we base our research
questions. Interdependence theory represents the notion that one’s attitudes and behaviors are a
reflection of their own and those of others with whom they are interacting. Thus, we were
interested in how individuals’ own prejudiced attitudes, as well as prejudice at the group level
(represented by multiple other group members’ prejudiced attitudes) predicted individuals’ own
interactions with these peers. Some isolates in our data may truly have no friends or may have
few peer interactions. In this case, our research questions are not applicable to them and
collapsing them into these models arguably runs counter to what we are attempting to address.
Other isolates in our data may have friends and peers with whom they interact but these may be
“weaker” friendships in that they were identified as isolates because their nominations were not
reciprocated by the other students. In this case, too, proceeding to model the effects of grouplevel prejudice with just their single score and not those of these other peers conceptually would
be a misspecification of the model. Ideally, direct attention to isolates as a unique group of youth
would be an important area of inquiry, but this goes beyond the scope of our study, and mixing
them in with youth who were identified as clear members of a group seems to misrepresent the
issue we wish to address. Still, to be thorough in dealing with this, we include the analyses and
models in this online supplement document. Again, however, we caution the use and
interpretation of these analyses.
Table S1
Factor Analysis for Positive and Negative Interaction Indices
Factor 1 Loadings
Factor 2 Loadings
Scale
(Positive Interactions)
(Negative Interactions)
Intimate Disclosure
.85
.05
Emotional Support
.83
.03
Reliable Alliance
.50
-.07
Antagonism
.04
.83
Conflict
-.06
.78
Pressure
-.00
.53
Eigenvalue
2.05
2.02
Variance accounted for
27.82%
26.46%
Table S2
Estimated Fixed Effects for Single Time Point Models without Inconsistent Group Members
T2 Positive Interactions
T2 Negative Interactions
Sexual orientation
-0.19 (0.24)
-0.35** (0.13)
[-0.66, 0.29]
[-0.62, -0.09]
Gender
0.65** (0.16)
0.00 (0.07)
[0.33, 0.97]
[-0.14, 0.14]
Age
0.07 (0.05)
0.08* (0.03)
[-0.03, 0.18]
[0.01, 0.15]
Individual aggression T2
0.18 (0.10)
0.28** (0.10)
[-0.01, 0.37]
[0.09, 0.47]
Individual prejudice T2
-0.05 (0.04)
0.09** (0.03)
[-0.13, 0.04]
[0.03, 0.14]
Group size
0.00 (0.01)
0.01 (0.01)
[-0.03, 0.03]
[-0.01, 0.04]
Group sexual orientation composition
0.27 (0.15)
-0.01 (0.10)
[-0.03, 0.57]
[-0.20, 0.18]
Group aggression T2
0.07 (0.25)
0.27 (0.19)
[-0.43, 0.58]
[-0.11, 0.66]
Group prejudice T2
-0.10 (0.07)
0.13* (0.06)
[-0.24, 0.04]
[0.02, 0.25]
Note. T2 = Time 2. Estimated fixed effects are unstandardized coefficients. Values in
parentheses are standard errors; values in brackets are 95% confidence intervals for the estimated
effects.
* p < .05. ** p < .01.
Table S3
Estimated Fixed Effects for Socialization Models without Inconsistent Group Members
Sexual orientation
Gender
Age
Individual pos. interactions T1
Individual neg. interactions T1
Individual aggression T1
Individual prejudice T1
Group size
Group sexual orientation composition
Group pos. interactions T1
Group neg. interactions T1
T2 Positive Interactions
-0.40* (0.19)
[-0.78, -0.02]
0.29* (0.14)
[0.02, 0.56]
0.00 (0.04)
[-0.07, 0.07]
0.78** (0.06)
[0.67, 0.89]
—
0.03 (0.11)
[-0.18, 0.25]
-0.01 (0.03)
[-0.06, 0.04]
-0.02 (0.01)
[-0.04, 0.01]
0.23* (0.10)
[0.02, 0.44]
0.67** (0.14)
[0.38, 0.96]
—
T2 Negative Interactions
-0.41** (0.13)
[-0.66, -0.16]
0.03 (0.07)
[-0.11, 0.17]
0.00 (0.03)
[-0.06, 0.06]
—
0.54** (0.09)
[0.36, 0.71]
0.06 (0.11)
[-0.16, 0.28]
0.03 (0.02)
[-0.01, 0.06]
0.00 (0.01)
[-0.01, 0.02]
0.05 (0.07)
[-0.09, 0.18]
—
0.77** (0.11)
[0.55, 0.99]
Group aggression T1
0.39 (0.22)
0.02 (0.14)
[-0.04, 0.81]
[-0.26, 0.30]
Group prejudice T1
-0.11 (0.06)
0.11** (0.03)
[-0.22, 0.01]
[0.04, 0.17]
Note. T1 = Time 1; T2 = Time 2; Time 1 positive interactions are included as predictors in the
model for T2 positive interactions; Time 1 negative interactions are included as predictors in the
model for T2 negative interactions. Estimated fixed effects are unstandardized coefficients.
Values in parentheses are standard errors; values in brackets are 95% confidence intervals for the
estimated effects.
* p < .05. ** p < .01.
Table S4
Estimated Fixed Effects for Single Time Point Models Including Isolates
T2 Positive Interactions
T2 Negative Interactions
Sexual orientation
0.10 (0.22)
-0.20 (0.13)
[-0.34, 0.54]
[-0.46, 0.05]
Gender
0.71** (0.11)
-0.08 (0.06)
[0.49, 0.93]
[-0.20, 0.05]
Age
0.03 (0.04)
0.08** (0.03)
[-0.06, 0.11]
[0.02, 0.15]
Individual aggression T2
0.08 (0.11)
0.28** (0.09)
[-0.13, 0.29]
[0.10, 0.45]
Individual prejudice T2
-0.05 (0.04)
0.08** (0.03)
[-0.13, 0.03]
[0.03, 0.13]
Group size
0.00 (0.01)
0.01 (0.01)
[-0.01, 0.02]
[-0.01, 0.03]
Group sexual orientation composition
0.26 (0.13)
0.06 (0.09)
[0.00, 0.51]
[-0.12, 0.23]
Group aggression T2
0.24 (0.16)
0.16 (0.13)
[-0.08, 0.57]
[-0.10, 0.41]
Group prejudice T2
-0.06 (0.04)
0.09* (0.04)
[-0.14, 0.02]
[0.01, 0.17]
Note. T2 = Time 2. Estimated fixed effects are unstandardized coefficients. Values in
parentheses are standard errors; values in brackets are 95% confidence intervals for the estimated
effects.
* p < .05. ** p < .01.
Table S5
Estimated Fixed Effects for Socialization Models Including Isolates
Sexual orientation
Gender
Age
Individual pos. interactions T1
Individual neg. interactions T1
Individual aggression T1
Individual prejudice T1
Group size
Group sexual orientation composition
Group pos. interactions T1
Group neg. interactions T1
T2 Positive Interactions
-0.16 (0.18)
[-0.52, 0.20]
0.39** (0.10)
[0.20, 0.58]
-0.03 (0.04)
[-0.10, 0.04]
0.77** (0.05)
[0.66, 0.87]
—
-0.04 (0.10)
[-0.23, 0.15]
0.00 (0.03)
[-0.06, 0.05]
0.00 (0.01)
[-0.02, 0.01]
0.26* (0.10)
[0.06, 0.46]
0.55** (0.09)
[0.38, 0.73]
—
T2 Negative Interactions
-0.30** (0.11)
[-0.51, -0.09]
-0.12 (0.06)
[-0.25, 0.00]
-0.01 (0.02)
[-0.05, 0.04]
—
0.52** (0.08)
[0.37, 0.67]
0.07 (0.09)
[-0.11, 0.25]
0.03 (0.02)
[-0.01, 0.06]
0.01 (0.01)
[-0.01, 0.02]
0.11 (0.07)
[-0.03, 0.25]
—
0.53** (0.09)
[0.36, 0.70]
Group aggression T1
0.18 (0.17)
0.00 (0.14)
[-0.16, 0.53]
[-0.28, 0.28]
Group prejudice T1
-0.04 (0.03)
0.03 (0.02)
[-0.10, 0.03]
[-0.02, 0.08]
Note. T1 = Time 1; T2 = Time 2; Time 1 positive interactions are included as predictors in the
model for T2 positive interactions; Time 1 negative interactions are included as predictors in the
model for T2 negative interactions. Estimated fixed effects are unstandardized coefficients.
Values in parentheses are standard errors; values in brackets are 95% confidence intervals for the
estimated effects.
* p < .05. ** p < .01.