Bias Blind Spot: They rated themselves lower than others in both susceptibility to biases & personal shortcomings; belief in free will was positively associated with the susceptibility to better than average effect

Agency and self-other asymmetries in perceived bias and shortcomings: Replications of the Bias Blind Spot and extensions linking to free will beliefs. Prasad  Chandrashekar et al. March 2019. DOI: 10.13140/RG.2.2.19878.16961

Description: Bias Blind Spot is the phenomenon that people tend to perceive themselves to be less susceptible to biases than others. In three pre-registered experiments with samples from Hong Kong and the United States (overall N = 969), we replicated two experiments (Study 1-Survey 2 and Study 2) from Pronin, Lin, and Ross (2002), the first published demonstration of the effect. Participants rated themselves lower than others in both susceptibility to biases (mini meta-analysis: dz = - 1.00) and personal shortcoming (mini meta-analysis: dz = - 0.34). The self-other asymmetry of susceptibility for biases was larger than that of personal shortcomings (dz = - 0.43). Thus, the replication findings provide strong empirical support for the bias blind spot phenomenon. Extending the replications, belief in free will was positively associated with the susceptibility to better than average effect, and also with a stronger self-other asymmetry in rating personal shortcomings.


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The bias blind spot is the phenomenon that people tend to perceive themselves as less
biased than others in their judgements and behaviors (Pronin, 2007; Pronin et al., 2002) and
further tend perceive their peers as more subject to the bias blind spot than they are. Broadly,
people seem to be able to detect or infer biases in others but fail to do so about themselves
(Pronin, Gilovich, & Ross, 2004). 
We had two main goals for the present investigation: (1) to conduct replications of the
bias blind spot effect, and (2) to examine extensions about the link between agency beliefs and
the bias blind spot. The proposed extension was meant to answer further calls for future research
to investigate possible “causes of people’s unwarranted faith in their own introspections?”
(Pronin, 2007, p. 41). We begin by introducing the literature on the bias blind spot and the chosen
target article for replication - Pronin et al. (2002). We then introduce agency beliefs and
hypothesize about the relationship between free will beliefs and the bias blind spot effect.
Bias blind spot and free will beliefs                  5
Bias blind spot
People have access to their own private mental lives but not to that of others, and so to
overcome this information asymmetry people continuously aim to detect and infer other people's
internal psyche. This information asymmetry often results in unintended and unaware self-other
attributional asymmetries (Nisbett & Ross, 1980). 
Many such attribution asymmetries have been documented over the years, such as the
widely discussed actor-observer bias (Jones & Nisbett, 1972), in that divergent responses of
others are perceived to reflect others’ stable personality dispositions (Jones, 1990). Individuals
also tend to believe and perceive their perceptions of the world are objective and accurate, coined
as "naïve realism" (Ross & Ward, 1995), easily detecting flaws in this assumption in others but
failing to detect such flaws in themselves. They may further assume that they self-reflect more
than others do, since when people evaluate their own behaviors and judgments, they base their
evaluations on introspection, whereas when evaluating others their assessments must rely on
others' behavior (Pronin, 2007; Pronin et al., 2004; Ross & Ward, 1995; Wilson & Dunn, 2004).
Finally, people tend to view themselves in a positive light or construe reality in a way that would
make for a more positive self-evaluations. Together, naïve realism, introspection illusion, and
self-enhancement motives, result in a bias blind spot, a self-other asymmetry in perceptions bias.
People further reject and persist in their biased perceptions even if being made aware of its
existence (Ehrlinger, Gilovich, & Ross, 2005; Pronin, 2007; Pronin & Kugler, 2007).
The chosen bias blind spot experiments
Pronin et al. (2002)’s work was the first demonstration of the bias blind spot. The article
has been influential with over 765 citations according to Google Scholar at the time of writing,
with theoretical developments and applications across several domains, such as judgment and
Bias blind spot and free will beliefs                  6
decision making, behavioral economics, assessment, and interpersonal and intergroup conflict
(e.g., Pronin et al., 2004). Bias blind sport is argued to be a distinct meta-bias with clear
implications on judgment and behavior (Scopelliti et al., 2015). For example, subsequent
empirical research showed relevance of the effect to law in viewing and remembering criminal
events (Jones, Crozier, & Strange, 2018), with observations of the effect in children as young as
six years old (Hagá, Olson, & Garcia-Marques, 2018), and evidence for the persistence of bias
despite being shown how it affected previous decisions (Hansen, Gerbasi, Todorov, Kruse, &
Pronin, 2014). To the best of our knowledge, there have been no previous attempts for a direct
replication of the experiments reported in the paper. 
The target article consisted of three experiments, and the current replications focused on
Survey 2 of Study 1 and Study 2. Findings in Pronin et al. (2002) and summarized in Table 1.
In their Study 1, participants separately rated their own and average Americans'
susceptibility to eight cognitive and motivational biases and three personal shortcoming biases.
Pronin et al. (2002) proposed that participants would demonstrate clear asymmetry in
susceptibility to biases but not to shortcoming items because people are likely to be aware of their
visible personal shortcomings than their invisible cognitive biases. In view of this, they proposed
and tested three hypotheses. The first hypothesis suggested that participant would rate themselves
as less susceptible than others on biases. The second hypothesis suggested that there should be no
difference between the rating of self-susceptibility and other’s susceptibility towards personal
shortcomings (null hypothesis). The third hypothesis combining the first two suggested that
asymmetries effects would, therefore, be larger for biases than for personal shortcoming items.
Bias blind spot and free will beliefs                  7
In their Study 2, participants compared themselves to others on six personality
dimensions, three positive and three negative. Findings indicated that participants rated
themselves as higher on positive personality dimensions and lower on negative ones, compared to
others. Furthermore, a large majority (76 %) of participants who claimed better-than-average
status insisted on this status even when alerted to the possible bias.
Adjustments to original design
We attempted a close replication of the original study by Pronin et al. (2002) yet made
several needed adjustment. First, we administered all surveys via an online Qualtrics survey.
Second, the two studies from Pronin et al. (2002) chosen for replication included Stanford
University undergraduate students and were not paid for completion of the study. The current
replication effort of three studies included one undergraduate sample from a university in HK,
and two paid samples using Amazon Mechanical Turk (MTurk). Thirdly, Study 2 and Study 3
replications combined the original article' Studies 1 and 2 into an integrated design. Forth, we
went beyond the replication and added extensions to the original design to examine the link
between agency beliefs and self-other bias asymmetries.
Extensions - belief in free will as a predictor of the bias blind spot
We aimed to extend the replication study by considering individuals’ perceived agency as
a predictor of the bias blind spot - whether perceiver’s beliefs in free will predict self-other
asymmetries regarding biases and personal shortcomings. Belief in free will is the general belief
that human behavior is free from internal and external constraints across situations (Feldman,
2017; Monroe & Malle, 2014). Studies on folk understanding of free will found that people
normally associate free will with having choice and understand free will as the absence of
Bias blind spot and free will beliefs                  8
internal and external constraints (Baumeister, 2008; Feldman, Baumeister,  & Wong, 2014;
Monroe, Dillon,  & Malle, 2014; Monroe & Malle, 2010; Vonasch, Baumeister, & Mele, 2018).
Belief in free will has been associated with a range of adaptive behavioral and
psychological outcomes such as academic and job performance (Feldman, Chandrashekar, &
Wong, 2016; Stillman et al., 2010), perseverance for long-term goals (Li, Zhao, Lin, Chen, &
Wang, 2018), self-control (Goto, Ishibashi, Kajimura, Oka,  & Kusumi, 2018), expressions of
love (Boudesseul, Lantian, Cova, & Bègue, 2016), job satisfaction (Feldman, Farh, & Wong,
2018), cooperation (Protzko, Ouimette, & Schooler, 2016), and well-being and meaning in life
(Crescioni, Baumeister, Ainsworth, Ent, & Lambert, 2016; Moynihan, Igou, & van Tilburg,
2017).
Although the research outlined above largely emphasize the effects of believing in free
will on individuals’ self-regulatory behavior, some recent work suggests that free-will beliefs
affect fundamental social-cognitive processes that are implicated in the judgements of self and
others. For example, Genschow, Rigoni, and Brass (2017) found a positive relationship between
the strength of the belief in free will and the correspondence bias, i.e., tendency to endorse
dispositional explanations than situational explanations. People with a strong belief in free will
tend to view the actions of wrongdoers as the result of choices that are freely made and therefore
endorse harsher punishments (Clark et al., 2014; Martin, Rigoni, & Vohs, 2017). Similarly, free
will beliefs influence judgements about the extent to which individuals’ choices determine their
economic outcomes (Mercier et al., 2018), and more broadly form the basis of a capacity for
change, not only for others but also for the self (Feldman, Wong, & Baumeister, 2016).
Bias blind spot and free will beliefs                  9
As discussed above, several findings are suggestive of the possible relationship between
free will beliefs and the bias blind spot. Personal shortcomings can be viewed as a form of
internal constraints of free will (e.g., fear of public speaking, planning fallacy, and
procrastination). Those with stronger free will beliefs are likely to perceive own behaviors as the
outcome of their own choices (Feldman et al., 2014) and have more control over decisions in life
(Rigoni, Kühn, Gaudino, Sartori, & Brass, 2012; Stillman, Baumeister, & Mele, 2011). In
summary, free will beliefs reflect a view of the self as an active agent with freedom to choose
actions and pursue goals, and therefore, should encourage the view of the self as devoid of
internal constraints that may impose limitations on self’s ability to make choices. Supporting this
view, people with a history of addiction to alcohol, tobacco, and other drugs rate themselves
lower on belief in free will (Vonasch, Clark, Lau, Vohs, & Baumeister, 2017). This is suggestive
of a negative relationship between free will beliefs and perceived personal shortcomings.
Furthermore, the work on the association between free will beliefs and correspondence bias
suggest that free-will beliefs would be associated with perceiving others as more affected by their
personal shortcomings.  Combined, the two are suggestive of a positive relationship between free
will beliefs and bias blind spot regarding personal shortcoming. We initially made no pre
registered predictions regarding perceived biases although similar arguments can be made.
Exploratory Hypotheses
We did not make priory predictions regarding associations between free will beliefs and
susceptibility to biases of the self and others. Belief in free will at its core is experienced as an
increased sense of agency, therefore believers perceive their own behaviors as generated by
themselves, rather than external forces (Rigoni et al., 2012). They therefore view their own
judgements and behaviors as lacking in biases, and by extension, may exhibit larger self-other
Bias blind spot and free will beliefs                  10
asymmetry in perceived bias. Extending on this argument toward susceptibility to better than
average effect, the belief in free will likely to be negatively associated with ratings of negative
personality dimensions of self in comparison to others, and positively associated with positive
personality dimensions of self in comparison to others.
Overview of empirical studies
There was a two weeks gap between the two data collections of Studies 1 and 2. In each of
the replication studies, we first pre-registered the experiment on the Open Science Framework
(OSF) and data collection was launched later that week. Pre-registrations, power analyses, and all
materials used in these experiments are available in the supplementary materials. OSF pre
registration review links: Study 1a -
https://osf.io/fwthk/?view_only=744526890b674a9fbec72acc37a79c86 ; Study 1b -
https://osf.io/qmcrn/?view_only=4820ad08078b4b5a860b08c0234c7229 ; Study 2 -
https://osf.io/fm48b/?view_only=60e6cf6df39147e0af1b28f4e7da0d4c.
In light of findings from the first two studies, Study 3 was designed to extend the findings.
Importantly, we wanted to replicate the proposed extensions in the Study 2 with a larger sample
to be able to detect smaller effect sizes. We preregistered our hypotheses and analysis plan on the
OSF, review link: https://osf.io/u3vds/?view_only=42450fc3d6b74866a1c022e7bfd299a9. 
Data and R/RMarkdown code for all studies is available on the OSF, review link:
https://osf.io/3df5s/?view_only=b29f8571eb874448907ce45c7379e371 . Full open-science
details and disclosures are provided in the supplementary. All measures, manipulations,
exclusions conducted for this investigation are reported, all studies were pre-registered with
Bias blind spot and free will beliefs                  11
power analyses reported in the supplementary, and data collection was completed before
analyses. 
Studies 1a and 1b
Studies 1a and 1b were meant as a pre-test of the effects in an undergraduate class.
Students worked in teams of 3-6 to design and run a series of replications, two of those were
Pronin et al.'s Study 1 Survey 2 and Study 2 corresponding to our Study 1a and 1b. The students
then served as the target sample for the experiments designed by their classmates, experiments
they were not involved in designing and had no prior knowledge of. The course materials covered
judgement and decision-making biases, which meant that the students were made aware a wide
array of other biases, and the experiments are, therefore, very conservative tests of the effect in a
non-naive sample.
Students were randomly assigned into groups and to the study for replication. Student
groups designed the survey, conducted effect size and confidence intervals calculations,
conducted power analyses, and wrote the pre-registrations for Studies 1a and 1b. The course
instructor completed the pre-registration on OSF and data collection. All the students registered
in the course were invited to take part as respondents in the study. To ensure anonymity, students
were only asked to indicate which replication group they belonged to and those were later
excluded from the data analysis of the study they designed. 
Participants and procedures
A total of 49 undergraduate students took part in the online course survey, and of those we
excluded the four students who designed Study 1a and six students who designed Study 1b,
Bias blind spot and free will beliefs                  12
resulting in a sample of 45 for Study 1a (Mage = 20.20, SD = 0.99; 31 females) and 43 for Study
1b. 
Study 1a
Measures
Biases and Personal shortcomings. 
Participants were presented with descriptions of eight biases and three personal
shortcomings: self-serving attributions for success or failures, dissonance reduction after free
choice, positive halo effect, biased assimilation of new information, reactive devaluation of
proposal one’s negotiation counterparts, perceptions of hostile media bias toward one’s group or
cause, fundamental attribution error (FAE) in “blaming the victim,” and judgments about the
“greater good” influences personal self-interest, procrastination, fear of public speaking, and
planning fallacy. The supplementary includes detailed descriptions of the biases and personal
shortcomings.
For each of the descriptions participants rated on their own susceptibility and
susceptibility of the average student at the university. Ratings were on a nine-point scale (1 = not
at all; 9 = strongly). 
Results and discussion
Descriptive statistics of the ratings on the susceptibility to bases biases and personal
shortcomings are presented in Table 2 (see supplementary for the descriptive statistics and plots
for each of the biases and personal shortcomings). We conducted the paired sample t-test to test
the hypothesis, summarized in Table 3.
Bias blind spot and free will beliefs                  13
Results of paired t-tests (one-tailed) indicated that participants, consistent with the original
study, reported themselves as less susceptible to biases (M = 5.60, SD = 0.86), than the average
students in the university (M = 6.35, SD = 0.91), Md  = -0.75, t (44) = -4.54, p <.001, dz = -0.68,
95% CI [-1.01, -0.35] (Plotted in Figure 1). Self-others asymmetry was found for all individual
biases except for cognitive dissonance (Table S3 in the supplementary).
In the original study, the authors made no prediction regarding self-other personal
shortcomings asymmetry. We conducted a two-tail dependent t-test but failed to find support for
any differences with a weak effect for high ratings of self (self: M = 6.20, SD = 1.78; others: M  =
6.49 , SD = 1.23; Md  = -0.29; t (44) = -1.13, p = .265; dz = -0.17, 95% CI [-0.47, 0.13]; see Figure
2 and Table S3 in the supplementary for details per each shortcoming). Quite possibly, as in the
original article, the small sample failed to detect a weak effect.
Finally, self-other bias asymmetry (M = -0.75, SD = 1.11) was stronger than self-other
personal shortcomings asymmetry (M = -0.29, SD = 1.72; Md = -0.46, t (44) = -1.97, p = .055, dz
= -0.29, 95% CI [-0.60, 0.01]; see Figure 3).
Study 1b 
Measures
Assessed Personality dimensions. 
Participants were presented with three positive and three negative personality dimensions
in randomized order. The positive personalities assessed were dependability, objectivity, and
consideration. The negative personalities assessed were snobbery, deceptiveness, and selfishness.
The ratings were made on a 9-points (1 = much lower than the average student; 5 = same as the
average student; 9 = much higher than the average student).
Bias blind spot and free will beliefs                  14
Bias recognition. 
After rating their personalities, participants were briefed of the better-than-average effect
and asked whether they were influenced by the bias when assessing their personalities (1  -
Objective measures would rate me lower on positive characteristics and higher on negative
characteristics than I rated myself; 2 - Objective measures would rate me neither more positively
nor more negatively than I rated myself; 3 - Objective measures would rate me higher on positive
characteristics and lower on negative characteristics than I rated myself). 
Results and discussion
Table 4 details descriptive statistics and Table 5 summarizes statistical tests (Table S4 in
the supplementary details ratings for each personality dimension).
We conducted one-sample one-tail t-tests and found that participants rated themselves as
having more positive personality dimensions (M = 5.74, t (42) = 5.09, p < .001, dz = 0.78, 95% CI
[0.43, 1.11]) and less negative personality dimensions than others (M = 4.16, t (42) = -4.55, p <
.001, dz = -0.69, 95% CI [-1.02, -0.36]). 
We then conducted a chi-squared test to test the hypothesis that the majority of
participants deny having the better-than-average effect, comparing to a 50%-50% random split.
Despite being made aware of the potential bias, only 9 of the 43 participants (21%)
acknowledged their potential bias leaving 79% of participants still claiming to be better than their
average peers (χ2 (1, N = 43) = 14.53, p < .001, dz = 1.43, 95% CI [0.69, 2.16]). 
Findings supported the better than average effect and denial of their own bias. Effect size
(dz = 1.43) of the replication was almost two times greater than the effect size of the original
Bias blind spot and free will beliefs                  15
study (dz  = 0.70) and the replication’s confidence intervals ([0.69, 2.16]) includes the original
effect size point estimate. We conclude the replications as successful.
Study 2
Method
Participants and procedures
A total of 303 American Amazon Mechanical Turk (MTurk) participants completed the
study using TurkPrime.com (Mage = 38.45, SD = 11.58; 166 females). First, participants rated
their free will beliefs on two scales and then rated their and others susceptibility to the
descriptions of eight biases and three personal shortcomings. The design was a 2 (self and other
ratings) by 2 (biases and personal shortcomings) within-subject design and display of conditions
was counterbalanced (see supplementary for more details and full measures). Participants then
answered a funneling section and provided demographic information. 
Measures
Belief in Free will. 
Free will beliefs (BFW) were measured using two free-will belief subscales: 5 items
measure of general BFW (Nadelhoffer, Shepard, Nahmias, Sripada, & Ross, 2014) (1 = Strongly
disagree, 7 = Strongly agree; 𝛼 = 0.91) and BFW personal agency subscale (Rakos, Laurene,
Skala, & Slane, 2008) (4 items; 1 = Not true at all, 5 = Almost always true; 𝛼 = 0.92). Details of
all measures are provided in the supplementary. 
Bias blind spot and free will beliefs                  16
Biases and Personal shortcomings. 
Similarly to Study 1a, participants rated their own and other average Americans
susceptibility to biases and personal shortcomings (1 = not at all; 9 = strongly).
Results
Descriptive statistics are provided in Table 6 and statistical tests summary in Table 7 (see
Table S6 and Table S7 and Figures S5 to S8 in the supplementary for each of the biases and
personal shortcomings separately).We conducted a dependent sample t-test and found that
participants' perceived susceptibility to biases for self (N = 303; M = 4.64, SD = 1.35) was lower
than of others (M = 5.78, SD = 1.16 ; Md = -1.15; t (302) = -16.16, p < .001; dz = -0.93, 95% CI [
1.06, -0.79]; see Figure 4), and the self-other asymmetry effects were similar across all eight
biases (p < .001; see Table S8 in supplementary). In comparison, the original study found support
for only four of the eight biases and with weaker effects, possibly due to lacking power.
The original study found no support for self-other asymmetry in perceived personal
shortcomings, and the hypothesis was for a null (or weaker) effect. We conducted a dependent
sample t-test and found perceived personal shortcomings (M = 5.35, SD = 1.88) were lower than
perceived susceptibility to biases of other MTurk workers (M = 5.87, SD = 1.35; Md  = -0.52; t
(302) = -5.22, p <.001, dz = -0.30, 95% CI [-0.42, -0.18]; see Figure 5). The original study
reported self as lower than others for all three perceived personal shortcomings, yet it was not
reported if any of the results reached statistical significance. Our dependent sample t-tests found
support for an asymmetry for two out of three personal shortcomings (procrastination and
planning fallacy; see Table S8 in supplementary for details on each of the personal
shortcomings). These findings deviate from the findings of the original study.
Bias blind spot and free will beliefs                  17
Based on the findings in the original study, we expected a significant difference between
the biases and personal shortcomings asymmetries. We conducted a dependent sample t-test and
indeed found that self-other biases asymmetry (M = -1.15, SD = 1.24) was larger than the self
other personal shortcomings asymmetries (M = -0.52, SD = 1.75; N = 303 ; Md = -0.62, t (302) =
6.39, p <.001, dz = -0.37, 95% CI [-0.48, -0.25]; see Figure 6).
Finally, we examined the link between free will beliefs and perceived personal
shortcomings of self and others. Pearson correlations are detailed in Table 8. Both free will
beliefs scales were negatively correlated with perceived self personal shortcomings (general free
will: r = -0.22, p < .001, 95% CI [-0.32, -0.11]; personal agency: r = -0.17, p = .003, 95% CI [
0.28, -0.06]). However, we found no support for a link between free will beliefs measures and
perceived shortcomings in others (general free will: r = 0.00, p = .941, 95% CI [-0.11, 0.12];
personal agency: r = 0.05, p = .357, 95% CI [-0.06, 0.16]). Free will beliefs negatively correlated
with personal shortcomings self-other asymmetry (general free will: r = -0.24, p < .001, 95% CI
[-0.34, -0.13]; personal agency: r = -0.22, p < .001, 95% CI [-0.33, -0.11]). 
Probing the link between free will beliefs and susceptibility to biases we only found
support for personal agency subscale as negatively correlated with self-other asymmetry for
susceptibility to bias (r = -0.17, p  = .003, 95% CI [-0.28, -0.06]). We did not find support for
correlations between free-will beliefs and any of the measures associated susceptibility to biases:
self-bias (general free will: r  = -0.01, p = .811, 95% CI [-0.13, 0.10]; personal agency: r = -0.11, 
p = .055, 95% CI [-0.22, 0.00]), and others' bias (general free will: r = 0.02, p = .737, 95% CI [
0.09, 0.13]; personal agency: r  = 0.05, p = .366,  95% CI [-0.06, 0.16]).
Bias blind spot and free will beliefs                  18
Study 3
Method
Participants and procedures
A total of 621 American MTurk participants completed the study using TurkPrime.com
(Mage = 39.15, SDage = 11.88; 346 females). The rationale of the present study was as follows:
First, to test the robustness and reliability of the replication results found in Study 1a, Study 1b,
and Study 2 with a larger sample. Second, more importantly, replicate the proposed extension
hypotheses between free will beliefs and perceived personal shortcomings of self and others. 
Study 3 combined Study 1a and Study 1b as one single study. Procedures were modeled to
remain as close as possible to the original studies. The study included three parts. Participants
first completed the measures of free will beliefs. Then, in randomized order, participants rated
their and others susceptibility to given descriptions of eight biases and three personal
shortcomings, and compared themselves to others on three positives and three negative
personality dimensions with a test for recognition of their bias.
Measures
The measures for biases and personal shortcomings followed the design of Study 2. The
measures of personality dimensions and bias recognition followed were the same as Study 1b.
Free will beliefs were measured by three of the most common scales: eight items of the free-will
and determinism personal will sub-scales (Rakos et al., 2008) (0 = Not true at all, 4 = Almost
always true; 𝛼  = 0.74), five items of the general free will beliefs scale (Nadelhoffer et al., 2014)
(1 = Strongly disagree, 7 = Strongly agree; 𝛼 = 0.89) and the seven items from free will and
Bias blind spot and free will beliefs                  19
determinism plus scale (Paulhus & Carey, 2011) (1 = Not at all true, 5 = Always true; 𝛼  = 0.85;
recoded from a scale of 0 to 4 to match the original scale range).
Results
Table 9 details descriptive statistics and Table 10 summarizes statistical tests (see Table
S11 and Table S12 and Figures S9 to S12 in supplementary for each of the biases and personal
shortcomings separately).
Perceived susceptibility to bias and personal shortcomings
We conducted a series of dependent sample t-test mirroring Studies 1a and 2 (N = 621).
Perceived susceptibility to biases was lower for self (M = 4.69, SD = 1.30) than for others (M =
6.48, SD = 1.04; Md  = -1.80; t (620) = -32.04, p <.001, dz = -1.29, 95% CI [-1.39, -1.18]; see
Figure 7), in all biases (p < .001; see Table S13 in supplementary). Perceived shortcomings were
lower for self (M = 5.52, SD = 1.71) than for others (M = 6.25, SD = 1.16; Md = -0.73; t (620) =
10.54, p <.001, dz = -0.42, 95% CI [-0.51, -0.34]; see Figure 8), especially in procrastination and
planning fallacy (see Table S13 in supplementary). Self-other asymmetry was larger for biases
(M = -1.80, SD = 1.40) than for personal shortcomings (M = -0.73, SD = 1.73; Md  = -1.06; t (620)
= -13.01, p <.001, dz = -0.52, 95% CI [-0.61, -0.44]; see Figure 9). The results align with the
findings in Study 2.
Denying Personal Susceptibility to the Better Than Average Effect
We conducted a series of one-sample t-tests mirroring Study 1b. Participants rated
themselves as possessing more positive personality dimensions (M = 6.42; t (620) = 31.74, p
<.001; dz = 1.27, 95% CI [1.17, 1.38]) and less negative personality dimensions (M = 3.21; t
(620) = -30.38, p <.001; dz = -1.22, 95% CI [-1.32, -1.11]), compared to others. 
Bias blind spot and free will beliefs                  20
To assess denial of the bias, we conducted a chi-square comparing to a 50%-50% split.
Only 109 of the 621 participants (18%) admitted bias, leaving 82% denying the bias (χ2 (1, N =
621) = 261.53, p < .001; dz = 1.71, 95% CI [1.50, 1.91]).
Free-will beliefs and biases
Finally, we examined the link between free will beliefs and perceived personal
shortcomings of self and others. Pearson correlations are detailed in Table 11.
Belief in free will and personal shortcomings. 
Personal shortcomings for self was negatively associated with free-will beliefs (general: r
= -0.16, p < .001, 95% CI [-0.23, -0.08]; personal agency: r = -0.15, p < .001, 95% CI [-0.22,
0.07]; personal will: r = -0.09, p = .022, 95% CI [-0.17, -0.01]). However, we found no consistent
support for a link between free will beliefs measures and perceived shortcomings in others
(general: r = 0.02, p = .551, 95% CI [-0.05, 0.10]; personal agency: r = 0.05, p = .231, 95% CI [
0.03, 0.13]; personal will: r = 0.11, p = .007, 95% CI [0.03, 0.18]). 
Free will beliefs negatively correlated with personal shortcomings self-other asymmetry
(general free will: r = -0.17, p < .001, 95% CI [-0.25, -0.09]; personal agency: r = -0.18, p < .001,
95% CI [-0.25, -0.10]; personal will: r = -0.16, p < .001, 95% CI [-0.24, -0.09]).
Probing the link between free will belief and susceptibility to biases we found support for
personal will as negatively correlated with susceptibility to bias of the self (r = -0.14, p < .001,
95% CI [-0.22, -0.06]) and positively correlated with the susceptibility to bias of others (r = 0.12,
p = .003, 95% CI [0.04, 0.20]). Overall personal will was negatively correlated with self-other
asymmetry for susceptibility to bias (r = -0.22, p < .001, 95% CI [-0.29, -0.14]). We found no
Bias blind spot and free will beliefs                  21
support for a correlation with the two other measures of free will beliefs (correlations ranged
between 0.01 CI [-0.07, 0.09] and -0.03 CI [-0.11, 0.05]).
Belief in free will and better than average effect 
We found support for an exploratory negative relationship between free-will beliefs and
negative personality dimensions (general free-will: r = -0.09, p = .033, 95% CI [-0.16, -0.01];
personal agency: r = -0.16, p < .001, 95% CI [-0.23, -0.08]; personal will: r = -0.12, p = .003,
95% CI [-0.20, -0.04]). Positive personality dimensions were positively correlated with personal
will (r = 0.15, p < .001, 95% CI [0.07, 0.23]), but no support for a positive correlation with the
two other measures (General free will: r = 0.04, p = .341, 95% CI [-0.04, 0.12]; Personal agency:
r = 0.05, p = .222, 95% CI [-0.03, 0.13]).
Denial of bias correlated with general free-will (r = 0.11, p = .007, 95% CI [0.03, 0.19])
and personal agency (r = 0.14, p < .001, 95% CI [0.06, 0.22]), with no support for personal will
(r = 0.03, p = .531, 95% CI [-0.05, 0.10]). 
Overall, the results of the free will related findings are consistent with the results of Study
2.
General Results: Mini Meta-Analysis
We summarized the findings of the three studies together with the findings from original
article using a mini meta-analysis to assess the overall effect size (Goh, Hall, & Rosenthal, 2016;
Lakens & Etz, 2017). The overall effects for Study 1 Survey 2 of the original study were as
follows: bias asymmetry = -0.98 (95% CI = [-1.25, -0.72], p < .001) (see Figure  10), personal
Bias blind spot and free will beliefs                  22
shortcomings asymmetry = -0.19 (95% CI = [-0.47, 0.08], p = .158) (see Figure 11), bias versus
shortcomings difference = -0.44 (95% CI = [-0.56, -0.32], p < .001) (see Figure 12).
Similarly, overall effects for Study 2 of the original study were as follows: better than
average effect for positive personality dimensions = 1.22 (95% CI = [0.78, 1.66], p < .001) (see
Fig. 13), better than average effect for negative personality dimensions = -1.07 (95% CI = [-1.39,
-0.75], p < .001) (see Fig. 14), and denial to better than average effect = 1.32 (95% CI = [0.72,
1.91], p < .001) (see Fig. 15).
General Discussion
Summary and evaluation of replications
We conducted three replication studies of two studies from Pronin et al. (2002), testing the
bias blind spot effect. We summarized the findings of the three replication studies in Table 12.
Overall, we found that: (1) participants' perceived their susceptibility to biases as lower than that
of others, (2) participants perceived their own personal shortcomings as lower than that of others,
(3) bias asymmetry was larger than personal shortcomings asymmetry, (4) participants rated
themselves as higher on positive personality dimensions and lower on negative personality
dimensions, and (5) denied exhibiting the bias. 
The first aim of the current replication effort is to evaluate—in a confirmatory manner—
the size of an effect observed in the original study. To interpret the replication results we
followed the framework by LeBel, McCarthy, Earp, Elson, and Vanpaemel (2018) that take into
account three distinct statistical aspects of the results: (a) whether a signal was detected in the
replication (i.e., the confidence interval for the replication Effect size (ES) excludes zero), (b)
Bias blind spot and free will beliefs                  23
consistency of the replication ES with the original study’s ES, and (c) precision of the
replication’s ES estimate. The replication ES for asymmetry in bias in three individual studies
ranged between dz = -0.68 [-1.01, -0.35] and dz = -1.29 [-1.39, -1.18]. When pooled across all
studies with a mini-meta analysis, the overall estimate of the ES was: dz = -1.00 [-1.33, -0.67].
The results indicate signal was detected and that the replication ES is consistent with the original
study, i.e., the replication’s confidence interval includes the original ES point estimate of 0.86.
The replication results testing the asymmetry in personal shortcomings across three studies
ranged between dz = -0.17 [-0.47, 0.13] and dz = -0.42 [-0.51, -0.34]. Comparing the meta
analytic estimate (dz = -0.34 [-0.46, -0.23]) with original study suggest that, although, a signal
was detected, the replication ES is inconsistent and opposite in direction with the original ES
point estimate of 0.28. Therefore, a less favorable replication outcome suggesting small sample
size in the original study may have contributed to the observed effect. Finally, the hypothesis
testing the asymmetry between bias and personal shortcomings in current replication studies, ES
ranged between dz = -0.29 [-0.60, 0.01] and dz = -0.52 [-0.61, -0.44]. Meta-analytic estimate of
the ES (dz = -0.43 [-0.56, -0.29]) is inconsistent with the original ES point estimate of -0.61, i.e.,
similar in direction but smaller than the ES of the original study.
We followed a similar approach to summarize the replication of Study 2 of Pronin et al.
(2002). The replication ES’s for better than average effect for positive personality dimensions
were dz = 0.78 [0.43, 1.11] (Study 1b) and dz = 1.27 [1.17, 1.38] (Study 3). Meta-analytic
estimate of the ES (dz = 1.05 [0.57, 1.54]) is inconsistent with the original study’s ES point
estimate of 1.61, i.e., similar in direction but smaller than the ES of the original study. The
replication ES’s for better than average effect for negative personality dimensions were dz = -0.69
[-1.02, -0.36] (Study 1b) and dz = -1.22 [-1.32, -1.11] (Study 3). Meta-analytic estimate of the ES
Bias blind spot and free will beliefs                  24
(dz = -0.98 [-1.49, -0.47]) is consistent with the original study’s ES point estimate of -1.24.
Similarly, the replication ES for denial of bias were dz = 1.43 [0.69, 2.16] (Study 1b) and dz =
1.71 [1.50, 1.91] (Study 3). Meta-analytic estimate of the ES (dz = 1.69 [1.49, 1.88]) is
inconsistent with the original study’s ES point estimate of 0.76, i.e., similar in direction but larger
than the ES of the original study. 
In summary, the replication results show that ESs are similar in direction with the original
study for all the hypothesis tested and indicated signal (i.e., ES excludes zero) except for the
prediction of asymmetry in perceived shortcomings. As noted above effect size estimates in some
cases were inconsistent with the original study. However, we note that the sample size employed
in the original study was small. Overall, the replication results provide reasonable support for the
findings of the original study.
Agency beliefs extension
In Studies 2 and 3 we ran extensions examining the link between free will beliefs and the
bias blind spot effects, and the findings are summarized in Table 13. 
To this end, we pre-registered the theoretical relationship between the strength of belief in
free will on individuals’ tendency toward bias blindness and better than average effect. Overall,
our findings provide support for the hypothesis that belief in free will is linked asymmetry in
perceived personal shortcomings of self and of others. This particular asymmetry is mainly
driven by the negative correlation between BFW and perceived personal shortcomings. The
findings are in line with the recent findings that indicate that people’s view on the free will
question can affect fundamental cognitive processes. Most importantly, belief in free will is
associated with an increased sense of agency (Lynn, Muhle-Karbe, Aarts, & Brass, 2014) and
Bias blind spot and free will beliefs                  25
self-efficacy (Baumeister & Brewer, 2012). In the similar vein, current findings support the view
that more people believe in free-will the less they perceive the personal shortcomings of the self
because of the agentic view that their own behavior is generated by themselves (e.g., desires,
goals), rather than by constraints. Across two studies, results confirm the hypothesis.
The exploratory hypothesis that tested for the relationship between free will beliefs and
magnitude of blind spot related to biases did not indicate conclusive support. However, we did
not find any effects to the opposite direction, but rather effects indistinguishable from zero. The
findings suggest that free will may not have a meaningful influence on the invidious distinctions
people make between their own and others’ susceptibility to bias. Previous work by Genschow et
al. (2017) finds that free will beliefs are positively correlated with correspondence bias. The
current finding suggests free will beliefs not have the same nature of the relationship with
individuals’ susceptibility towards other kinds of biases.
Findings of study 3 are in support of the pre-registered exploratory hypothesis that belief
in free was negatively associated with negative personality dimensions (snobbery, deceptiveness,
and selfishness). Findings are consistent with the theoretical view that belief in free will is
associated with moral responsibility. For example, Vohs and Schooler (2008) found that inducing
disbelief in free will increased participants’ cheating behavior. Similarly, Baumeister,
Masicampo, and DeWall (2009) found that an attenuated belief in free will reduce participants’
pro-social inclinations. Martin et al. (2017) find that free will beliefs positively related to harsher
punishments of unethical behavior. Negative personality dimensions included in the current study
do correspond to the moral responsibility in a person. However, we found no support for the
prediction that free will beliefs are positively correlated with positive personality dimensions.
Results suggest that belief in free will may not be associated with better than average effect in
Bias blind spot and free will beliefs                  26
regards to positive personality dimensions. The lack of support for this hypothesis is consistent
with the theoretical argument that free will underlies laypersons’ sense-making for accountability
and choice more so under negative circumstances (Feldman, Wong, & Baumeister, 2016).
However, the results of the correlation between free will beliefs and the extent of denial of bias is
positive and significant. 
In summary, results from the pre-registered extension hypotheses indicated that direction
of correlation holds in almost all cases: with a couple of exceptions (noted above). When the
exceptions occur to the pre-registered hypothesis, we did not find effects to the opposite
direction, but rather effects indistinguishable from zero. 
Conclusion
We aimed to replicate and extend previous findings of bias blind spot effect that refer to
the tendency to see bias in others while being blind to it in ourselves. For the most part, we
replicated the results reported by Pronin et al. (2002). The study contributes to the recent call for
systematic, large-scale, and preregistered replication and validation studies. Additionally, the
present investigation explored the relationship between free will beliefs and the tendency to
impute bias more to others than to the self is rooted. We extended the literature on bias blind spot
exploring the sources of bias blind spot (e.g., Pronin & Kugler, 2007).