Supplemental Materials
Super-Capacity Me! Super-Capacity and Violations of Race Independence for Self- but
not for Reward-Associated Stimuli
by J. Sui et al., 2015, JEP: Human Perception and Performance
http://dx.doi.org/10.1037/a0038288
Experiment 1: Self vs. friend biases—capacity analyses
Confirmatory analyses were conducted on the peak of the capacity coefficient. The results
showed a significant main effect of association, F(1, 19) = 36.43, p < .001, η2 = .66, reflecting that
there was a greater peak capacity coefficient in the self than the friend association condition. The
effect of shape and the interaction between the association and shape were not significant, ps > .34.
After this we computed the relative length of the time window over which super-capacity was
demonstrated across the entire time window for responses made by individual participants (the
number of time bins where capacity coefficient C(t) > 1 divided by the total number of time bins for
the participant). A repeated-measures ANOVA was conducted with association (self vs. friend) and
shape (same vs. different). This revealed a significant main effect of association, F(1, 19) = 49.36, p <
.0001,η2 = .72; the relative length of the time window where super-capacity was manifested was
larger for self trials (mean and s.e.: 28% ± 4%) than for the friend trials (mean and s.e.: 2% ± 1%).
Neither the main effect of shape nor the interaction between association and shape were significant,
ps > .41.
Experiment 2: High vs. low reward biases
Analyses on peak capacity coefficient did not reveal any significant variations across the
conditions, ps > .64. Subsequently, the relative length of the time window where super-capacity was
evident was calculated for each participant using the percentage scores (the number of time bins
with super-capacity divided by the number of bins across the whole time window for that
individual). A repeated-measures ANOVA was conducted with the factors being association (high vs.
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low reward value) and shape (same vs. different). None of the effects were significant, ps > .42 for
the main effect of association and the association × shape interaction (There was a marginal
significant main effect of shape, F(1, 18) = 3.83, p = .07, η2= .18; there was a wider time window
when the stimuli were the same relative to when they were different).
Cross-experiment comparisons
We further conducted ANOVAs on peak capacity coefficient measures with the experiment
(self vs. reward) as a between-subjects variable and the association (self or high reward value vs.
friend or low reward value) and the shape (two same vs. two different shapes) as two withinsubjects variables. The analysis on the peak capacity coefficient showed a significant interaction
between the experiment and the association, F(1, 37) = 20.81, p < .001, η2 = .36. The post-hoc t tests
showed that there was greater peak capacity coefficient for self than for friend associations, t(19) =
6.04, p < .001, but there was no significant difference between the high and low reward associations,
p = .64. An independent t test between the self and reward experiments showed that there was a
larger peak capacity coefficient for self (mean ± s.e.: 6.24 ± 0.74) than high reward associations
(mean ± se: 2.09 ± 0.31), t(37) = 5.07, p < .001, whereas there was no significant difference between
the friend (mean ± s.e.: 1.30 ± 0.35) and low reward associations (mean ± s.e.: 1.88 ± 0.15), p = .13. A
one-sample t test showed super capacity in all conditions, t(19) > 2.05, p = .05 and < .05. No other
significant interactions involving the experiment were significant, ps > .30. The main effect of
experiment was significant, t(37) = 17.67, p < .001, reflecting the presence of a greater peak capacity
coefficient for the self than the reward associations.
Linear regression analyses. In order to assess the contributions of the different parameters
derived from the capacity analyses to the redundancy gain, we performed linear regression analyses
to investigate whether the relative size of the super capacity window, the super capacity coefficient
(model 1) and the peak capacity coefficient (model 2) could predict the magnitude of the
redundancy gain. The analyses consistently revealed that the size of the window over which super
2
capacity was observed could predict the magnitude of redundancy gain both for two same selfassociated stimuli (p < .001). There were also consistent trends across the models for two different
self-association stimuli (p = .07 in model 1 and .06 in model 2). There were no reliable predictors for
friend, high, or low reward associations (see Supp. Tables 1 and 2).
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Table S1
Linear Regression Analysis on Redundancy Gains as Dependent Variable and Super Capacity
Coefficient and the Time Window Over Which Super-Capacity Was Demonstrated Across the
Entire Time Window as Independent Variables
Association
Personal
Salience
Reward
Self
Friend
High
Low
Level
Same
Diff
Same
Diff
Same
Diff
Same
Diff
Super
capacity
.150
-.112
-.114
-.192
-.150
.127
.012
-.051
the time
window of
super
capacity
.638**
.422(p=.07)
.013
-.033
-.205
-.427
.101
.394
R
.659
.452
.111
.214
.286
.339
.110
.360
** p < .001.
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Table S2
Linear Regression Analysis on Redundancy Gains as Dependent Variable and the Peak of Capacity
Coefficient and the Time Window Over Which Super-Capacity Was Demonstrated Across the Entire
Time Window as Independent Variables
Association
Personal
Salience
Reward
Self
Friend
High
Low
Level
Same
Diff
Same
Diff
Same
Diff
Same
Diff
peak capacity
coefficient
.091
-.038
-.122
-.319
.314
.053
.063
-.145
the time
window of
super capacity
.674**
.437(p=.06)
.041
.065
-.362
-.341
.054
.451
R
.647
.440
.108
.379
.384
.333
.114
.376
** p < .001.
1
Experiments 1 and 2 are adapted from Experiments 2 and 3 in Sui and Humphreys (sub. a). What is novel
here are the data analyses we perform to provide detailed tests of the dynamics of the redundancy gains for
the various stimuli. However, the Method is reported in order to enable readers to replicate the study without
referring back to the earlier paper. By using the detailed mathematical analyses, the present study focuses on
the relations between self- and reward-biases. In contrast, the paper of Sui and Humphreys (sub. a) focuses on
the role of expectancy in self bias, contrasting additional conditions in which self information was primed.
2
Note that these procedures were not applied in Sui and Humphreys (sub.a).
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