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Judgment and Decision Making, Vol. 15, No. 5, September 2020, pp. 741–755
A reﬂection on cognitive reﬂection – testing convergent/divergent
validity of two measures of cognitive reﬂection
Nikola Erceg∗Zvonimir Galić†Mitja Ružojčić‡
The aim of the study was to test convergent/discriminant validity of two measures of cognitive reﬂection, cognitive reﬂection
test (CRT) and belief bias syllogisms (BBS) and to investigate whether their distinctive characteristic of luring participants into
giving wrong intuitive responses explains their relationships with various abilities and disposition measures. Our results show
that the same traits largely account for performance on both non-lure task, the Berlin Numeracy Test (BNT), and CRT and
explain their correlations with other variables. These results also imply that the predictive validity of CRT for wide range of
outcomes does not stem from lures. Regarding the BBS, we found that its correlations with other measures were substantially
diminished once we accounted for the eﬀects of BNT. This also implies that the lures are not the reason for the correlation
between BBS and these measure. We conclude that the lures are not the reason why cognitive reﬂection tasks correlate with
diﬀerent outcomes. Our results call into question an original deﬁnition of CRT as a measure of ability or disposition to resist
reporting ﬁrst response that comes to mind, as well as the validity of results of studies showing “incremental validity” of CRT
Keywords: cognitive reﬂection; belief bias; lures; numeracy; convergent validity
To make a rational decision, frequently we need to take time
to deliberate, question the idea that ﬁrst comes to mind and
reﬂect on the available information before deciding. This
principle lead Frederick (2005) to construct a short three-
item measure in which every question was designed in a way
that triggers an intuitive, impulsive answer that is always in-
correct. In order to resist reporting the (inaccurate) response
that ﬁrst comes to mind, it is presumed that a person needs
to “reﬂect“ on it and engage in slower and more deliberate
thinking that is required to realize the correct response. Be-
cause of this characteristic, the test was named the Cognitive
Reﬂection Test (CRT). In his seminal paper, Frederick re-
ported that for the majority of students the CRT was quite
hard, in spite the fact that it requires only basic mathematical
skills to be correctly solved. The CRT was also shown to be
related to diﬀerent measures of cognitive abilities and ana-
This work is a part of the project “Implicit personality, decision making
and organizational leadership” funded by the Croatian science foundation
(Grant no. 9354).
Data can be found at https://osf.io/zctme/.
Copyright: © 2020. The authors license this article under the terms of
the Creative Commons Attribution 3.0 License.
∗Faculty of humanities and social sciences, University of Zagreb, Ivana
Lučića 3, 10000 Zagreb, Croatia. email: nerceg@ﬀzg.hr. ORCID:0000-
†Faculty of humanities and social sciences, University of Zagreb. OR-
‡Faculty of humanities and social sciences, University of Zagreb. OR-
lytic cognitive style, but the correlations were low enough to
allow the conclusion that the CRT and other used cognitive
measures “likely reﬂect common factors, but may also mea-
sure distinct characteristics, as they purport to“ (Frederick,
2005, p. 35).
Since then, the CRT became popular among researchers
because of its brevity and the fact that it was able to pre-
dict an incredibly wide range of cognitive and behavioral
outcomes. Speciﬁcally, CRT has been found to predict per-
formance on a range of tasks from the heuristics and biases
(H&B) domain. For example, the CRT score was nega-
tively correlated with susceptibility to the conjunction fal-
lacy and conservatism in updating probabilities (Oechssler,
Roider & Schmitz, 2009), and the base rate fallacy (Hoppe
& Kusterer, 2011), and positively correlated with a general
indicator of resilience to using mental shortcuts, as indi-
cated with a composite of 15 diﬀerent H&B tasks, including
sample size problem, gambler’s fallacy, Bayesian reason-
ing, framing problem, sunk cost and others (Toplak, West
& Stanovich, 2011). Moreover, the predictiveness of the
CRT spans outside the cognitive domain. CRT was found to
predict religious belief (Pennycook, Cheyne, Seli, Koehler
& Fugelsang 2012; Shenhav, Rand & Greene, 2012), po-
litical orientation (Deppe et al., 2015; Pennycook & Rand,
2019), science understanding (Shtulman & McCallum, 2014,
Gervais, 2015), moral reasoning (Paxton, Ungar & Greene,
2012; Royzman, Landy & Goodwin, 2014) and suscepti-
bility to pseudo-profound bullshit statements (Pennycook,
Cheyne, Barr, Koehler & Fugelsang, 2015; see Pennycook,
Fugelsang & Koehler  and Pennycook & Ross 
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 742
for a detailed account of predictiveness of the CRT across
Such breadth of the CRT bears the following question:
where does this predictivity of the CRT come from? On the
one hand, the CRT might be such a potent predictor because,
similarly to some other non-lure measures (e.g., numeracy),
it assesses diﬀerent cognitive capabilities (i.e., abilities in
a narrow sense, as discussed in Baron, 1985) and thinking
dispositions that substantially account for performance on
diﬀerent tasks that the CRT predicts. For example, CRT was
found to be highly correlated with “general cognitive ability”
(e.g., Blacksmith, Yang, Behrend and Ruark 2019; Freder-
ick, 2005) as well as with numerical ability (Campitelli &
Gerrans, 2014; Finucane & Gullion, 2010; Liberali, Reyna,
Furlan, Stein & Pardo, 2012; Primi et al., 2016; Thom-
son & Oppenheimer, 2016; Welsh, Burns and Delfabbro,
2013). To a certain extent, the CRT also assesses think-
ing dispositions, broadly deﬁned as the tendencies towards
particular patterns of intellectual behavior (Tishman & An-
drade, 1996). One example is reﬂection/impulsivity (R/I),
disposition to be careful at the expense of speed so those that
are reﬂective are willing to sacriﬁce the eﬃciency and speed
in responding in order to be more accurate (Baron, 2018;
Baron, Scott, Fincher and Metz (2015); Baron, Gürçay &
Metz, 2017). This view also follows from the results that
show positive correlations between response time and ac-
curacy on the CRT (e.g., Frey, Johnson & De Neys, 2017;
Stupple, Pitchford, Ball, Hunt & Steel, 2017) and, in this
regard, CRT might not be especially diﬀerent from other
tasks in which slower and more careful responding can lead
to more accurate responses. Therefore, the traits that inﬂu-
ence performance on any cognitive task that asks for both
ability and deliberation (either with or without lures), might
account for the predictive potency of the CRT.
On the other hand, the CRT has a distinctive characteristic
of luring participants into incorrect intuitive responses that,
allegedly, need to be detected and overridden in order to come
up with correct response responsible. Some authors believe
that this characteristic of the test should be mostly respon-
sible for predictive potency of the CRT. In this regard, it is
said that the CRT measures some additional ability or dispo-
sition, not shared with non-lure measures, to resist reporting
a ﬁrst response that comes to mind (Frederick, 2005), some-
thing that might be termed cognitive miserliness (Stupple et
al., 2017; Toplak et al., 2011; Toplak, West & Stanovich,
2014). Thus, this additional ability or disposition could be
responsible for CRT’s correlation with various outcomes.
Therefore, a key question is whether the lures make the
CRT “special” or can some other, non-lure tasks predict the
same outcomes to a similar degree. Several recent studies ar-
gue that the lures or the disposition to reﬂect and correct the
intuitive wrong response are not important for the predictive
power of CRT. For example, Baron et al. (2015) concluded
that there is no evidence that “intuitive lures” matter at all for
reliability or predictive validity of the CRT. A recent piece
of evidence that the lures do not account for the predictive
potency of CRT comes from a study by Attali and Bar-Hillel
(2020). Across two studies, they showed that the latent CRT
factor and numerical factor formed with items without lures
were correlated so highly that they were practically factori-
ally indistinguishable. Their data showed that the predictive
power of the CRT items came from their quality as math
items and not from their “lureness”. This result goes against
the usual interpretation of CRT as a measure of some ad-
ditional dispositions uniquely assessed by lures and shows
that the lures are not the reason why CRT predicts perfor-
mance on diﬀerent cognitive tasks as well as various real life
outcomes. Thus, in our study we decided to constructively
replicate (Lykken, 1968) these ﬁndings using diﬀerent set of
CRT and well as math problems.
1.1 Our study
In our study, we investigated are the lures responsible for
the correlations that the CRT has with diﬀerent outcomes.
To strengthen our constructive replication of Attali and Bar-
Hillel (2020) study, in addition to CRT, we also used syllo-
gisms that assess belief bias (belief bias syllogisms, BBS) as
additional measure of cognitive reﬂection. Similarly to the
CRT, BBS also trigger intuitive but incorrect response that
needs to be detected and overridden in order to give a correct
response. In other words, BBS items have lures but, unlike
CRT, do not require participants to know math to solve them.
Baron et al. (2015) showed that BBS are valid cognitive re-
ﬂection items and they have been shown to predict perfor-
mance on H&B tasks similarly as the CRT (West, Toplak &
Stanovich, 2008). As non-lure tasks we used numeracy tasks
(Cokely, Galešić, Schulz, Ghazal & Garcia-Retamero, 2012)
and verbal reasoning items (Condon & Revelle, 2014).
In order to accomplish study aims we did three things.
First, we correlated our lure and non-lure measures with
diﬀerent tasks from the H&B domain (base-rate neglect,
four card selection, causal base rate, gambler’s fallacy and
availability bias tasks) and a thinking disposition measure
(AOT questionnaire). We chose these H&B tasks because
the cognitive reﬂection measures should be uniquely suited
for predicting them, better than the non-lure measures. This
view follows from the tripartite theory of mind (Stanovich,
2012; Pennycook, Fugelsang & Koehler, 2015a) that dif-
ferentiates between autonomous, algorithmic and reﬂective
parts of the mind. The bat-and-ball CRT problem elegantly
illustrates this: “A bat and a ball cost $1.10 in total. The bat
costs $1 more than the ball. How much does the ball cost?“
This problem automatically triggers relatively strong initial
response (i.e., 10 cents). However, after a more careful re-
ﬂection, it is clear that this is an incorrect answer, and that the
right response is in fact 5 cents. Thus, in order to overcome
the initial wrong response (generated by the autonomous
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 743
mind), and arrive to the correct one, one has to ﬁrst reﬂect
on the answer and recognize the need to engage in a more
deliberate processing (the reﬂective mind), but also to pos-
sess adequate computational power, knowledge and abilities
to calculate the right answer (algorithmic mind). Stanovich,
West and Toplak (2016), in their categorization of ratio-
nality tasks according to their dependence on the conﬂict
detection/knowledge, put both cognitive refection tasks and
H&B tasks on the same high level of dependence on the
conﬂict detection dimension. That means that both of these
two types of tasks cue intuitive but incorrect responses that
need to be detected and overridden (reﬂective mind) if the
task is to be solved correctly.
Conversely, according to the tripartite theory, non-lure
tasks, or the tasks that do not depend on the conﬂict de-
tection (such as tests of ﬂuid intelligence), should capture
only algorithmic mind and not the dispositions towards ana-
lytic/reﬂective thinking that are unique to the tasks high on
the conﬂict detection dependence (Stanovich, 2009, 2012;
Pennycook, Fugelsang & Koehler, 2015). Thus, because
cognitive reﬂection and H&B tasks have this common char-
acteristic of triggering intuitive incorrect response and non-
lure tasks do not, correlations between these two types of
tasks should be greater than correlations between the non-
lure and H&B tasks.
Second, we aimed to replicate Attali and Bar-Hillel (2020),
who showed that one-factor model that did not diﬀerentiate
between CRT items and ordinary math problems showed
excellent ﬁt to their data. They concluded that CRT items
are essentially high quality math items and that the CRT’s
predictive value stems from the fact that it captures, what
they called, “mathematical ability” (p. 95). In other words,
the CFA suggested that the fact that the CRT items have
lures did not ensure that they capture diﬀerent construct than
the regular math problems. In the current study, we seek
to constructively replicate their results with diﬀerent sets of
CRT and math problems. As non-lure math problems we
are using The Berlin Numeracy Test (BNT; Cokely et al,
2012). This measure of statistical numeracy is particularly
good test of convergent/discriminant validity of the CRT be-
cause BNT successfully predicted similar outcomes as CRT
such as the ability to evaluate and understand risks (Cokely
et al., 2012), maximization of expected value on monetary
lotteries (Sobkow, Olszewska, & Traczyk, 2020), ﬁnancial
literacy (Skagerlund, Lind, Strömbäck, Tinghög & Västfjäll,
2018) and performance on some of the H&B tasks (e.g.,
sunk cost, framing, base rate neglect, gambler’s fallacy, etc.;
Allan, 2018; Ghazal, 2014). There is also evidence that both
BNT and CRT assess similar thinking dispositions related to
deliberation, reﬂectiveness and actively open-minded think-
ing (Baron et al., 2015; Cokely, Feltz, Ghazal, Allan, Petrova
& Garcia-Retamero, 2018; Cokely & Kelley, 2009; Ghazal,
Cokely & Garcia-Retamero, 2014). Therefore, it is not sur-
prising that several previous studies that investigated both
CRT and BNT reported very high correlations between the
two (e.g., Cokely et al.  reported the correlation of r =
.56 (disattenuated r = .93), Skagerlund et al. (2018) reported
correlation of r= .61 (disattenuated r = 1) and Sobkow et
al. (2020) reported correlation of r = .59 (disattenuated r =
.90)). Taken together these results indicate that BNT as a
non-lure math measure is well suited for a replication of At-
talli and Bar-Hillel (2020) result that the CRT and non-lure
math problems load on the same factor. This would be an-
other evidence against the importance of lures in predicting
Finally, to make our conclusions about the importance of
lures more robust and expand on Attali and Bar-Hillel ﬁnd-
ings, we tested the importance of lures for predictiveness
of BBS tasks. If BBS and BNT predict H&B tasks for the
same reasons (i.e., not because of lures), than the correlations
between the BBS and the H&B tasks should be greatly di-
minished once we statistically account for the eﬀect of BNT
in these tasks.
506 undergraduate University of Zagreb students (67% Fac-
ulty of humanities and social sciences students, mostly psy-
chology students, and the rest from various other University
of Zagreb faculties), participated in the study (27% males).
The mean age was 21.2 (min = 18, max = 31, SD = 2.13).
a) Cognitive reﬂection tasks. We used two diﬀerent mea-
sures of cognitive reﬂection, the numerical one that required
certain levels of mathematical skills to come to the correct
responses and the verbal one and BBS that do not require
any mathematical knowledge.
We used an expanded, 10-item version of the CRT in
order to increase reliability and response range of the total
score. It consisted of three original CRT items (Frederick,
2005), but also additional items from previously reported
alternative CRT measures (Primi et al., 2015; Thomson &
Oppenheimer, 2016; Toplak et al., 2014). An example of an
item is “In an athletics team, tall members are three times
more likely to win a medal than short members. This year,
the team has won 60 medals so far. How many of these have
been won by short athletes?”. Here, the intuitive incorrect
answer is 20 and the correct one is 15. All the items are listed
in the Appendix. Total score was calculated by summing the
correct responses, thus one could score anywhere between
0 (if none of the responses were correct) and 10 (if all the
responses were correct).
BBS tasks assess the cognitive reﬂection byexamining the
susceptibility to belief bias. An example task goes as fol-
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 744
lows: “Premise 1: All ﬂowers have petals. Premise 2: Roses
have petals. Conclusion: Roses are ﬂowers.” (Markovits &
Nantel, 1989). According to this syllogism, it does not follow
that only ﬂowers have petals, so roses might as well be some-
thing other than ﬂowers (e.g., children collage art). However,
because the conclusion that roses are ﬂowers conforms with
our empirical reality, it is quite believable and many people
accept it as valid. Thus, the false intuitive response is the
product of believability of the conclusion, while strong con-
formity with logical principles is needed to come up with the
right, logically valid response. In addition to the “Roses have
petals” example we used three additional syllogisms whose
conclusions were believable, albeit logically incorrect (see
Appendix for all the tasks). We considered as correct the
response where participants identiﬁed believable conclusion
as logically incorrect. Participants’ scores ranged between 0
b) Non-lure cognitive ability tasks. We used The Berlin
numeracy test (BNT; Cokely et al., 2012) as a measure of
numeracy. The BNT is a four-question test for assessing nu-
meracy and risk literacy. An example of a question is “Imag-
ine we are throwing a ﬁve-sided die 50 times. On average,
out of these 50 throws how many times would this ﬁve-sided
die show an odd number (1, 3 or 5)?”. The questions are
designed in a way that they gradually become harder and a
total score is calculated by summing up the correct responses
on the four questions (see Appendix for all the items).
Verbal Reasoning (VR) was measured with four items
taken from the International Cognitive Ability Resource
(ICAR; for details see http://icar-project.com and Condon
& Revelle, 2014). VR items include diﬀerent logic, vocab-
ulary and general knowledge questions. All of the items are
presented in Appendix A.
c) Thinking dispositions. In this study we used a 15-item
AOT scale introduced by Campitelli and Gerrans (2014) as
a measure of thinking disposition. It is a self-report scale
where participants indicate their level of agreement with
the items on a six-point scale (1 – strongly disagree to 6 –
strongly agree). An example of an item is “It is OK to ignore
evidence against your established beliefs” (see Appendix A).
The total score on this scale is calculated as a mean level of
agreement with the items and can be anything between 1 and
d) H&B tasks.
Four-card selection problem. We used ﬁve diﬀerent
tasks that had the same structure (all of the items are pre-
sented in the Appendix). A rule was explicitly stated for each
of the items and participants were informed that the rule may
or may not be correct. Their task was to check the accuracy
of the rule by turning two cards of their choice. For exam-
ple, one of the items was: “Rule: If a card shows “5” on one
side, the word “Excellent” is on the opposite side. Which
two cards would you choose to turn to check the accuracy of
this rule?”. Participants then saw four cards that had num-
bers 5 and 3 and words “Excellent” and “Good” written on
the front side. The correct answer here would be to turn the
card containing number 5 and word “Good” because turning
only these two cards would allow one to conclude whether
the rule is correct or false. However, because the card with
word “Excellent” is present, participants could be lured to
turn it instead of the card “Good”, although for the rule to
be correct it does not matter what is behind the “Excellent”
and “3” cards (Nickerson, 1998). Picking the two accurate
cards to turn would be scored as 1 so the minimum score on
this task was 0 while the maximum was 5.
Base-rate neglect. Base-rate neglect task consisted of
ﬁve similar problems where the description of a person was
contrasted to the base-rate information. Speciﬁcally, there
were two possible answers, a stereotypical one (based on the
description of a person) and a base-rate consistent one. For
example, one of the items was: “Among the 1000 people
that participated in the study, there were 50 16-year-olds and
950 50-year-olds. Helen is randomly chosen participant in
this research. Helen listens to hip hop and rap music. She
likes to wear tight T-shirts and jeans. She loves to dance and
has a small nose piercing. Which is more likely? a) Helen
is 16 years old; or b) Helen is 50 years old.”
Here, the description of Helen was stereotypical for a
teenager. Thus, a person who heavily relies on this infor-
mation would respond with an “a”. However, a base-rate
information indicated that there is much greater probability
that randomly chosen participant is indeed a 50 years old.
Thus, a response “b” was coded as a correct one. However,
it has to be noted that technically this does not have to be a
correct response and that this depends on the diagnosticity
of the information in the task (i.e., the information could be
that Helen is a minor which would render a base-rate based
response incorrect1). Nevertheless, as the stereotypical re-
sponse is intuitive on these tasks and one needs to engage
in correcting this intuitive response in order to incorporate
base-rate information into a judgment (Barbey & Sloman,
2007; Pennycook, Fugelsang & Koehler, 2012), we always
coded a response based on base-rates as a correct one. The
correct responses were scored as 1 and the theoretical range
of scores was 0 to 5.
Causal base-rate. In the causal base-rate, participants
are provided with two conﬂicting pieces of information: one
is statistical and favors one decision while another is based on
personal, case-based experience and favors another decision
1We thank Guillermo Campitelli for this observation.
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 745
(Toplak et al., 2011; Stanovich et al., 2016). We present
one of the items we used here, and report all three in the
Professor Kellan, the director of a teacher prepa-
ration program, was designing a new course in hu-
man development and needed to select a textbook
for the new course. She had narrowed her deci-
sion down to one of two textbooks: one published
by Pearson and the other published by McGraw.
Professor Kellan belonged to several professional
organizations that provided Web-based forums for
its members to share information about curricular
issues. Each of the forums had a textbook evalu-
ation section, and the websites unanimously rated
the McGraw textbook as the better choice in ev-
ery category rated. Categories evaluated included
quality of the writing, among others. Just before
Professor Kellan was about to place the order for
the McGraw book, however, she asked an expe-
rienced colleague for her opinion about the text-
books. Her colleague reported that she preferred
the Pearson book. What do you think Professor
Kellan should do?
• a. She should deﬁnitely use the Pearson text-
• b. She should probably use the Pearson text-
• c. She should probably use the McGraw
• d. She should deﬁnitely use the McGraw
Here preference for the McGraw textbook indicates a ten-
dency to rely on the large-sample information in spite of
salient personal testimony. A preference for the Pearson
textbook indicates reliance on the personal testimony over
the large-sample information. Each item was scored one to
four. In this case, one point is given if a participant thinks
that a) She should deﬁnitely use the Pearson textbook while
four points are given if participant thinks that d) She should
deﬁnitely use the McGraw textbook.
Gambler’s fallacy. Gambler’s fallacy refers to the ten-
dency for people to see links between events in the past and
events in the future when the two are really independent
(Stanovich et al., 2016). Consider the following problem
which is one of the ﬁve we used (see Appendix for all the
When playing slot machines, people win some-
thing about 1 in every 10 times. Julie, however,
has just won on her ﬁrst three plays. What are her
chances of winning the next time she plays?
____ out of ____.
Here the correct answer is 1 out of 10 (it was scored as 1,
while all the other responses were scored as 0). However,
people that are prone to gambler’s fallacy would reason that,
since Julia already won three times in a row, her probability of
winning again would somehow need to be lower than 1 in 10.
This does not make sense as slot machine does not remem-
ber Julia’s previous outcomes and always presents outcomes
with the same 1/10 probability. We measure the gambler’s
fallacy with ﬁve items. We scored correct responses as 1 and
incorrect as 0, so the theoretical range of results was 0 to 5.
Availability bias. The availability heuristic refers to as-
sessing the frequency of a class or the probability of an
event by the ease with which instances or occurrences can
be brought to mind (Tversky & Kahneman, 1973). Avail-
ability or the ease of retrieval certain instances of events
is often inﬂuenced by the vividness or media exposure and
does not necessarily correspond to the true frequency of
such instances. For example, people might think that homi-
cide is much more common cause of death than the diabetes
(it is the opposite; this was one of our questions) because
homicides are often covered in media while diabetes com-
plications and deaths are rarely discussed publicly. In this
study, we followed a paradigm introduced by Lichtenstein,
Slovic, Fischhoﬀ, Layman and Combs (1978), by asking
participants which of the four pairs of lethal events is more
common. Choosing causes of death that are more vivid and
more covered in media is a sign of over-reliance on easily
available and retrievable information (Pachur, Hertwig &
Steinmann, 2012; Stanovich et al., 2016). Thus, we refer
to responses that follow from the availability heuristic even
in situations when this does not correspond to reality as the
availability bias. We scored the correct responses as 1 and
incorrect (based on the availability heuristic) as 0. Thus, the
score ranged from 0 (greatest availability bias) to 4 (lowest
Participants solved all the tasks as a part of a larger data col-
lection eﬀort in which they also solved a number of additional
tasks that were not part of the current study. The regular and
verbal CRT items were presented in four ﬁxed, but diﬀerent
sequences and these sequences were randomly distributed
across participants. All the other instruments were solved
in ﬁxed order. The students ﬁlled-in the tests and question-
naires on computers, in groups of 20 to 25 participants under
the supervision of the investigators. Participants were reim-
bursed with course credits and/or cinema card vouchers. The
whole testing session lasted up to two hours with a break of
10 to 15 minutes in the middle of a session. Upon reaching
half of our planned sample (N = 253) we changed some of
the measures and added some additional measures, mostly
related to H&B tasks. This is why all the analyses involving
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 746
Table 1: Descriptive statistics and correlations among all the variables. The G6 reliabilities are shown in the diagonal,
bivariate correlations are below the diagonal, correlations between the latent factors are above the diagonal.
M SD Min Max CRT BBS BNT VR AOT BRN FCS CBR GF AV
CRT 5.59 2.91 0 10 .92 .66 .93 .77 .26 .35 .34 .35 .04 .19
BBS 2.10 1.62 0 4 .55∗∗ .93 .68 .54 .32 .33 .25 .30 −.04 .13
BNT 1.56 1.12 0 4 .58∗∗ .42∗∗ .61 .80 .26 .41 .20 .41 −.03 .28
VR 3.50 0.81 0 4 .46∗∗ .33∗∗ .36∗∗ .64 .22 .27 .30 .40 .17 .45
AOT 4.51 0.65 1.87 6 .22∗∗ .28∗∗ .17∗∗ .14∗∗ .83 .26 .21 .23 .25 .18
BRN 2.71 1.86 0 5 .30∗∗ .30∗∗ .26∗∗ .15∗.25∗∗ .92 .25 .40 .27 .20
FCS 1.53 1.48 0 5 .28∗∗ .22∗∗ .14∗.19∗∗ .19∗∗ .22∗∗ .86 .22 −.08 .14
CBR 8.88 1.52 4 12 .22∗∗ .20∗∗ .19∗∗ .17∗∗ .16∗.28∗∗ .12∗.45 −.01 .40
GF 4.09 1.04 0 5 .05 −.03 −.01 .11 .20∗∗ .20∗∗ −.04 −.01 .76 .16
AV 2.72 1.19 0 4 .11 .11 .14∗.13∗.11 .19∗∗ .12 .23∗∗ .03 .79
Note. ∗p< .05, ∗p < .01; CRT – Cognitive reﬂection test; BBS – belief bias syllogisms; BNT – Berlin numeracy
testy; VR – verbal reasoning; AOT – actively open-minded thinking; BRN = base-rate neglect; FCS – four cards
selection task; CBR – causal base-rate; GF – gambler’s fallacy; AV – availability bias.
H&B tasks are done on the remaining half of the sample (N
To answer our ﬁrst question, whether the tasks with lures
exhibit greater correlations with H&B and thinking disposi-
tion tasks than our non-lure tasks, we calculated correlation
coeﬃcients among all our variables. We report these cor-
relations along with descriptive statistics and G6 reliability
coeﬃcient in Table 1.
In order to estimate the relationships among the variables
while accounting for the measurement error, we calculated
the correlations between the latent factors and reported them
in the upper part of the Table 1, above the diagonal. Prior to
that, we made sure that a one-factor structure ﬁts each of our
instruments well and that all of the items load suﬃciently on
their respective factors. We report the details of the analyses
and ﬁt indices for each of the factors in Appendix B. In short,
for each of the factors, a one-factor solution proved to be a
very good ﬁt. Most of the loadings were much higher than
.30, in fact only three of the total number of loadings did not
pass this cut-oﬀ: a) on VR factor, the ﬁrst item had loading
lower than .30; b) on GF factor, ﬁrst variable had loading
lower than .30; c) on AV factor, ﬁrst item had loading lower
than .30. Thus, we can conclude that majority of our items
are appropriate manifest indicators of their respective latent
factors and that it is appropriate to do further analyses on
By looking at the upper part of the correlation table, two
things are apparent. First, CRT and BNT factors correlate
so highly (r= .93) that it appears that these two factors
are empirically indistinguishable. Second, both our lure
(CRT and BBS) and non-lure measures (BNT and VR) show
moderate to high correlations with thinking disposition and
most of the H&B measures. In fact, the correlations of CRT
and BNT factors with H&B factors are remarkably similar,
and it does not appear that our data support the expectation
that the lure measures are related more with H&B tasks
than the non-lure measures. In fact, BNT factor correlated
more strongly with three H&B factors (BRN, CBR and AV
factors) than either CRT (test for diﬀerences in correlations:
z= 2.75; p= .00 for BRN and CBR; z= 5.56, p= .00 for
AV) or BBS factor (z= 1.73, p= .04 for BRN; z= 2.36, p=
.01 for CBR; z= 4.32, p= .00 for AV). The CRT factor did
not even correlate higher than BNT with the other measure
of cognitive reﬂection (i.e., BBS), even though the two are
allegedly measuring the same ability/disposition to resist
reporting initial, intuitive responses. The only case that a lure
measure correlated more than BNT with an outcome was of
the CRT-FCS correlation (z= 6.17; p= .00). However, even
here this correlation did not surpass the correlation between
VR factor (another non-lure measure) and FCS (z= 0.99, p
= .16). Thus, judging from the correlation matrix, it does
not seem that the lures gave either CRT or BBS additional
predictive power over the non-lure measures.
In the next two analyses, we investigated whether the CRT
and BNT are factorially indistinguishable and whether the
lures are responsible for the correlations between BBS and
H&B tasks. Speciﬁcally, if BBS predicts H&B tasks for the
same reason BNT predicts them (i.e., because the abilities
and thinking dispositions not related to lures that are im-
portant for all three types of tasks and the lures are not so
important), then the correlation between the BBS and the
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 747
0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75
Figure 1: Relationship between the CRT items loadings on
a single CRT-BNT factor and the lureness index of items.
H&B tasks should be greatly diminished once we statisti-
cally account for the eﬀect of BNT in these tasks. To assess
these parameters free from error and to control for the Type 1
errors, we used CFA and SEM methods (Westfall & Yarkoni,
To test whether the CRT and BNT are factorialy distin-
guishable, we compared a model where the correlation be-
tween the latent CRT factor and latent BNT factor was freely
estimated with the one where the correlation was ﬁxed at 1
(meaning that both CRT and BNT items loaded on a single
factor). Both models showed excellent ﬁt to the data (𝜒2(76)
= 57.07, p= .95; CFI = 1; TLI = 1; RMSEA = .00 for the
two correlated factors model and 𝜒2(77) = 58.61, p= .94;
CFI = .1; TLI = .1; RMSEA = .00 for the one factor model).
There was no signiﬁcant diﬀerences in the ﬁt between the
models, indicating that the latent factor of cognitive reﬂec-
tion is practically indistinguishable from the latent factor of
numeracy (Δ𝜒2(1) = 1.54, p= .22). To check whether the
CRT items factor loadings on this single factor are related
with lureness of the items, we calculated the correlation be-
tween the loadings and the lureness index, the proportion of
errors that were lures. We calculated the lureness index for
each of the items as a proportion of intuitive responses in
all incorrect responses on that speciﬁc item (we report the
Lureness of each of CRT items in Appendix C). The rela-
tionship between the loadings and the lureness is pictured in
the Figure 1 from which it is clear that the lures are not the
reason why the items loaded on single CRT-BNT factor that
ﬁtted the data best (r= -.08, p= .82).
To further strengthen our ﬁndings, we explored how
mathematical models developed by Campitelli and Gerrans
(2014) to assess CRTs construct validity ﬁtted to our data.
In short, Campitelli and Gerrans developed three models
which they called mathematical ability model (MATH), ra-
tional thinking model (RAT) and thinking disposition model
(DISP). The ﬁrst MATH model assumes that the CRT mea-
sures only mathematical ability and is equivalent to a re-
gression analysis in which CRT performance is predicted
only by the score in the numeracy test. The RAT and DISP
models assume that the CRT, in addition to mathematical
ability, also measures rational thinking (assessed by BBS)
and the thinking disposition of AOT. Campitelli and Gerrans
(2014) concluded that the “analyses provided very strong ev-
idence (BIC diﬀerence > 10) in favor of RAT and DISP over
MATH and that, “therefore, CRT is not just another numer-
acy test” (p. 441). On the contrary, and in accordance with
our ﬁndings that the CRT and BNT are factorially indistin-
guishable, our analyses showed that the MATH model ﬁtted
our data better than the RAT and DISP models (BIC (math)
= 3993.49; BIC (rat) = 4001.26; BIC (disp) = 4345.35).
Therefore, it seems that the CRT scores are best explained
by the same dimention that explains the BNT scores.
The ﬁnding that the traits that the CRT shares with non-
lure BNT tasks explain all the variance in the CRT tasks indi-
cates that the lures are not essential for the predictive power
of the CRT. These results replicate the results of Attali and
Bar-Hillel, although their explanation that CRT measures
“numerical ability” seems too narrow, as we believe that
both CRT and BNT also capture diﬀerent thinking disposi-
tions that might even be more important for their predictive
power than the “pure” mathematical ability.
As BBS are not math tasks, it did not make sense repeating
the same analysis that we did on CRT, i.e., checking whether
BNT and BBS are factorially indistinguishable. Therefore,
we conducted a diﬀerent analysis that helped us answer the
question of lure importance for (supposedly) cognitive re-
ﬂection measures. We wanted to see to what degree will
accounting for the eﬀects on BNT in BBS and H&B tasks
using SEM aﬀect the correlations between the BBS and H&B
factors. In order to do that, we speciﬁed a model in which a
BNT factor was regressed on each of the BBS and H&B fac-
tors, and left residual variance in the factors free to co-vary.
The results showed that, when the eﬀects of BNT were ac-
counted for in this way, all of the correlations between BBS
factor, H&B factors and AOT factors substantially decreased
and ceased to be signiﬁcant (for BRN from r= .33 to r= .01;
for FCS from r= .25 to r= .09; for CBR from r= .30 to r=
.03; for AV from r= .13 to r= -.03; for AOT from r= .32 to r
= .14). Judging from these results, it seems that the BBS cor-
relates with diﬀerent outcomes mostly for the same reasons
that the non-lure BNT correlates with these same outcomes.
Again, as for CRT, the most plausible conclusion seems to
be that the lures are not crucial for the predictiveness of the
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 748
Our study represents a test of convergent/discriminant valid-
ity of CRT and BBS, two types of tasks that are supposed
to capture the cognitive reﬂection construct. More specif-
ically, we wanted to explore whether their unique charac-
teristic of cuing a strong intuitively appealing, but wrong,
response is responsible for their correlations with diﬀerent
H&B tasks and thinking dispositions. We did this in several
diﬀerent ways. First, we compared the correlation coeﬃ-
cients between our two cognitive reﬂection measures with
lures (CRT and BBS) and H&B tasks with the correlations
between our non-lure tasks and H&B tasks. These corre-
lations were either the same or our non-lure BNT task was
correlated more strongly with H&B tasks. Second, we tested
whether the CRT and BNT are factorially indistinguishable
by comparing a two-factor model (CRT and BNT items load
on separate factors that are allowed to correlated) with a
one-factor model (CRT and BNT items load on the same
factor). The two-factor model did not show better ﬁt than
the one-factor model, meaning that the same underlying trait
probably aﬀected both CRT and BNT performance. Third,
using Campitelli and Gerrans (2014) formula, we tested a
model that presumes that the CRT responses depend only
on numeracy against the models that they, in addition to nu-
meracy, also depend on rational thinking skills and thinking
dispositions. The ﬁrst model described out data the best.
Numeracy was the only relevant predictor of the CRT re-
sponses, rational thinking (operationalized as BBS result)
and thinking dispositions (operationalized as AOT result)
did not contribute over numeracy. Fourth, in order to see
whether the lures are making the CRT items “good” items,
we correlated the lureness index of the CRT items with their
respective loadings on a one CRT – BNT factor. These
were not correlated meaning that whatever traits the CRT
and BNT have in common, the lures are not responsible for
it. Finally, we checked whether the correlations between the
BBS and outcomes (H&B tasks and AOT) would be dimin-
ished when we statistically account for the eﬀects of BNT
on BBS, H&B tasks and AOT. All of the correlations were
substantially smaller meaning that the BBS correlate with
H&B tasks and AOT mostly for the same reasons that the
BNT correlates with them. This represented another piece
of evidence that the correlations between BBS and outcomes
largely do not depend on the lures.
Our ﬁndings showed that essentially all the valid variance
in the CRT was explained by the numeracy factor as the
same traits that inﬂuence performance on the non-lure nu-
merical problems also inﬂuence performance on the CRT
tasks with lures. Thus, for whatever reasons CRT predicts a
wide range of outcomes described in the introduction, it has
probably little to do with the lures. The characteristic that
made the CRT items famous, ability to trigger false intuitive
responses, seems not to be the test’s characteristic responsi-
ble for its predictive validity. Performance on the CRT tasks
predicts outcomes because these are good math tasks, not
because these tasks require suppression of the initial wrong
response. One implication of these results is that diﬀerent
studies that utilized regression analysis to conclude that the
incremental validity of CRT over numeracy stems from lures
(e.g., Barr, Pennycook, Stolz & Fugelsang, 2015a,b; Liberali
et al., 2012; Pennycook, Cheyne, Barr, Koehler & Fugelsang,
2014; Trippas, Pennycook, Verde & Handley, 2015) might be
due to a) narrow measures of numeracy that did not capture
complete range of the disposition (at least not to the extent
that BNT does), b) low reliability of numeracy and CRT
measures making both measures imperfect and incomplete
measure of the numeracy construct (see Baron, et al., 2017
for a discussion about statistical control), or c) Type 1 error
characteristic of this kind of regression analysis (Westfall &
However, the key question is which abilities and/or dis-
positions account for performance on math tasks, whether
the lure or the non-lure ones. Attali and Bar-Hillel (2020)
call these traits “mathematical ability”. Although they do
not mean to imply that the traits aﬀecting CRT and BNT
responses are abilities in a narrow sense of capabilities free
from certain thinking dispositions, nevertheless this does
sound a bit narrow. Therefore, we would argue (along with
a lot of other authors, i.e. Baron et al., 2015; Cokely and
Kelley, 2009; Ghazal et al., 2014) that, in addition to mathe-
matical ability in a narrow sense, some thinking dispositions
must play role in the CRT and BNT performance and account
for their correlations with diﬀerent outcomes. Our ﬁnding
that non-math task (BBS) correlates with diﬀerent outcomes
for the same reasons as the math task (BNT) implies that
BNT (and consequently CRT) does not correlate with these
outcomes only because it assesses mathematical ability that
might account for these correlations. Instead, at least one
disposition could account for BBS and BNT correlations
with diﬀerent outcomes. This disposition might be reﬂec-
tive and careful approach to cognitive tasks that includes
taking more time in order to be more accurate, a disposition
referred to as R/I (Baron, 2018; Baron et al., 2015; Baron
et al., 2017). In their protocol analysis of decision mak-
ing under risk, Cokely and Kelley (2009) found that both
CRT and numeracy predicted higher number of verbalized
considerations on risk decision-making tasks and number
of considerations was further related both to the number of
normative correct responses and to the response times. The
authors concluded that CRT and numeracy are associated
with more careful, thorough, and elaborate cognition. In
line with this are the ﬁndings that there is sometimes a posi-
tive correlation between CRT score and CRT response time
(e.g., Baron et al., 2015; Stupple et al., 2017), as well as that
participants that scored higher on BNT performed better on
various tasks (lotteries, intertemporal choice, denominator
neglect, and conﬁdence judgments) because they deliber-
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 749
ated more during decision making and, in that way, more
accurately evaluated their judgments (Ghazal et al., 2014).
In sum, we can conclude that our results thus replicate
Attali and Bar-Hillel (2020) ﬁndings that all the systematic
variance in the numerical CRT can be explained by “the math
factor” where this factor is inﬂuenced both by math ability
and thinking dispositions (such as R/I). What seems to be
clear from this, as well as several previous studies (Attali &
Bar-Hillel, 2020; Baron et al., 2015) is that the lures are not
essential for the predictive validity of cognitive reﬂection
measures. In other words, our ﬁndings indicate that what
supposed to be a cognitive reﬂection test does not capture
the ability or disposition to resist reporting the response that
ﬁrst comes to mind (Frederick, 2005) but rather a stable char-
acteristic to be careful and reﬂective from the start. In this
regard it is similar to many of the others cognitive tests that
allow participants to sacriﬁce speed for accuracy. We also
tried to expand on Attali and Bar-Hillel results by examining
BBS as another measure of cognitive reﬂection. Similarly
as for the CRT, our results indicate that the lures do not play
important role in correlations between BBS and other tasks.
Thus, we doubt that either of cognitive reﬂection measures
actually measure cognitive reﬂection as deﬁned by Frederick
The conclusions of the current study are qualiﬁed by sev-
eral facts. First, as mentioned before, our sample consisted
of college students that are on average more intelligent, nu-
merate and open-minded than the general public. In this
particular case, this fact can be relevant. Namely, at least
some of the college students could have ample experience
with basic mathematical operations that are required to suc-
cessfully solve CRT items and through their education they
could have lots of opportunities to train their skills. This
means that some of the college students might have devel-
oped good mathematical intuitions that allow them to do ba-
sic mathematical operations swiftly and almost intuitively.
It is also in line with the “hybrid” dual-process model that
posits that not only incorrect but also correct responses can
be intuitively cued and with greater probability among those
more experienced in particular task (De Neys, 2017). How-
ever, this could in turn mean that the eﬀect of deliberation
and reﬂection on accuracy in solving CRT tasks would be
diminished in our sample. The other signiﬁcant drawback
of the study is the fact that the sample on which we calcu-
lated our correlations between our (non)lure tasks and H&B
tasks was halved. This could mean that the parameters are
estimated with lesser precision.
CRT is deemed to be a speciﬁc measure of cognitive reﬂec-
tion deﬁned as the ability or disposition to resist reporting
ﬁrst response that comes to mind because of its ability to cue
intuitive but incorrect responses that need to be detected and
overturned in order to produce a correct response. However,
it seems that neither the CRT nor BBS as another cognitive
reﬂection measure capture cognitive reﬂection conceptual-
ized in this way. This conclusion follows from the fact that,
in our study, the same traits that accounted for performance
on the non-lure cognitive task (those that do not cue intuitive
incorrect response) completely accounted for performance
on the CRT. This means that the lures do not capture any ad-
ditional disposition not captured by numerical non-lure tasks
and, thus, that they do not account for the broad predictive
ability of the CRT. Similarly to the CRT, the lures do not
appear to be especially important for the predictive ability of
BBS as its correlations with various outcomes were substan-
tially diminished once the eﬀect of non-lure task (BNT) was
statistically accounted for in a SEM regression. We believe
that cognitive reﬂection measures capture some basic cog-
nitive capabilities and thinking dispositions that allow them
to correlate with such a wide variety of tasks as well as real
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Appendix A: Items
1. A bat and a ball together cost 110 kunas. The bat costs
100 kunas more than the ball. How much does the ball
cost? Correct: 5; Lure: 10.
2. If it takes 5 machines 5 minutes to make 5 widgets, how
long would it take 100 machines to make 100 widgets?
Correct: 5; Lure: 100.
3. In a lake, there is a patch of lily pads. Every day, the
patch doubles in size. If it takes 48 days for the patch
to cover the entire lake, how long would it take for the
patch to cover half the lake? Correct: 47; Lure: 24.
4. Josip received a grade that is at the same time the ﬁf-
teenth highest and the ﬁfteenth lowest in the class. How
many students are there in his class? Correct: 29; Lure:
5. Simon decided to invest $8,000 in the stock market one
day early in 2008. Six months after he invested, on
July 17, the stocks he had purchased were down 50%.
Fortunately for Simon, from July 17 to October 17, the
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 752
stocks he had purchased went up 75%. At this point,
(a) a. broken even in the stock market,
(b) b. is ahead of where he began, (lure)
(c) c. has lost money (correct)
6. If 3 elves can wrap 3 toys in 1 hour, how many elves are
needed to wrap 6 toys in 2 hours? Correct: 3; Lure: 6.
7. In an athletic team, tall athletes are three times more
likely to win a medal than short athletes. This year the
team has won 60 medals so far. How many of those
medals were won by short athletes? Correct: 15; Lure:
8. A square shaped garage roof with 6 meters long edge is
covered with 100 tiles. How many tiles of the same size
are covering a neighbouring roof, which is also square
shaped, but with a 3 meters long edge? Correct: 25;
9. There are two swimming pools in a swimming facility
and in the summer they need to be ﬁlled with water. 100
liters of water are required to ﬁll the cube-shaped pool.
How many liters of water does it take to ﬁll a cube-
shaped pool but with a 3 times longer edges? Correct:
2700; Lure: 300.
10. 25 soldiers are standing in a line 3 meters apart from
each other. How many meters is the line long? Correct:
72; Lure: 75.
Belief bias syllogisms. (all are believable, but logically
1. Premise 1: All unemployed people are poor. Premise
2: Todorić* is not unemployed. Conclusion: Todorić
is not poor.
2. Premise 1: All ﬂowers have petals. Premise 2: Roses
have petals. Conclusion: Roses are ﬂowers.
3. Premise 1: All Eastern countries are communist.
Premise 2: Canada is not an Eastern country. Con-
clusion: Canada is not communist.
4. Premise 1: All things that have a motor need oil.
Premise 2: Automobiles need oil. Conclusion: Au-
tomobiles have motors
* Todorić is a well-known Croatian rich businessman
Berlin numeracy test.
1. Out of 1,000 people in a small town 500 are members of
a choir. Out of these 500 members in the choir 100 are
men. Out of the 500 inhabitants that are not in the choir
300 are men. What is the probability that a randomly
drawn man is a member of the choir? Please indicate
the probability in percent. Correct response: 25 %
2. Imagine we are throwing a ﬁve-sided die 50 times. On
average, out of these 50 throws how many times would
this ﬁve-sided die show an odd number (1, 3 or 5)?
Correct response: 30 out of 50 throws.
3. Imagine we are throwing a loaded die (6 sides). The
probability that the die shows a 6 is twice as high as the
probability of each of the other numbers. On average,
out of these 70 throws how many times would the die
show the number 6? Correct response: 20 out of 70
4. In a forest 20% of mushrooms are red, 50% brown
and 30% white. A red mushroom is poisonous with
a probability of 20%. A mushroom that is not red
is poisonous with a probability of 5%. What is the
probability that a poisonous mushroom in the forest is
red? Correct response: 50
1. What number is one ﬁfth of one fourth of one ninth of
2; 3; 4; 5 (correct); 6; 7.
1. Zach is taller than Matt and Richard is shorter that
Zach. Which of the following statements would be
(a) Richard is taller than Matt.
(b) Richard is shorter than Matt.
(c) Richard is as tall as Matt.
(d) It’s impossible to tell. (correct)
2. Joshua is 12 years old and his sister is three times as
old as he. When Joshua is 23 years old, how old will
his sister be?
35; 39; 44; 47 (correct); 53; 57.
1. If the day after tomorrow is two days before Thursday
then what day is today?
Friday; Monday; Wednesday; Saturday; Tuesday; Sunday
1. There are two kinds of people in this world: those who
are for the truth and those who are against the truth.
2. Changing your mind is a sign of weakness.
3. I believe we should look to our religious authorities for
decisions on moral issues.
4. No one can talk me out of something I know is right.
5. Basically, I know everything I need to know about the
important things in life.
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 753
6. Considering too many diﬀerent opinions often leads to
7. There are basically two kinds of people in this world,
good and bad.
8. Most people just don’t know what’s good for them.
9. It is a noble thing when someone holds the same beliefs
as their parents.
10. I believe that loyalty to one’s ideals and principles is
more important than “open-mindedness.”
11. Of all the diﬀerent philosophies which exist in the world
there is probably only one which is correct.
12. One should disregard evidence that conﬂicts with your
13. I think that if people don’t know what they believe in
by the time they’re 25, there’s something wrong with
14. I believe letting students hear controversial speakers can
only confuse and mislead them.
15. Intuition is the best guide in making decisions.
1. Among the 1000 people that participated in the study,
there were 995 nurses and 5 doctors. John is randomly
chosen participant in this research. He is 34 years
old. He lives in a nice house in a fancy neighborhood.
He expresses himself nicely and is very interested in
politics. He invests a lot of time in his career. Which is
(a) John is a nurse. (correct)
(b) John is a doctor.
2. Among the 1000 people that participated in the study,
there were 100 engineers and 900 lawyers. George is
randomly chosen participant in this research. George is
36 years old. He is not married and is somewhat intro-
verted. He likes to spend his free time reading science
ﬁction and developing computer programs. Which is
(a) George is an engineer.
(b) George is a lawyer. (correct)
3. Among the 1000 people that participated in the study,
there were 50 16-year-olds and 950 50-year-olds. Helen
is randomly chosen participant in this research. Helen
listens to hip hop and rap music. She likes to wear tight
T-shirts and jeans. She loves to dance and has a small
nose piercing. Which is more likely?
(a) Helen is 16 years old.
(b) Helen is 50 years old. (correct)
4. Among the 1000 people that participated in the study,
there were 70 people whose favorite movie was “Star
wars” and 930 people whose favorite movie was “Love
actually.” Nikola is randomly chosen participants in this
research. Nikola is 26 years old and is studying physics.
He stays at home most of the time and loves to play video
games. Which is more likely?
(a) Nikola’s favorite movie is “Star wars”
(b) Nikola’s favorite movie is “Love actually” (cor-
5. One international student conference was attended by
50% of Germans, 30% of Italians and 20% of Poles.
One of the participants, an architecture student, de-
scribed himself as a temperamental but friendly, fan of
football, good weather and pretty girls. In your opinion,
the participant is from:
(a) Germany (correct)
Four card selection task. The cards you see in front of
you are printed on both sides. The content of the cards is
determined by some rule. In this task, a rule is proposed to
determine the content of these cards. However, this rule may
or may not be correct.
To ﬁnd out if this rule is correct or not, we give you the
opportunity to turn two cards and see what’s on the back of
those cards. So, your job is to check that the rule described
in the task is correct by only turning two cards.
1. Rule: If a card shows “5” on one face, the word
“excellent” is on the opposite face. Which two
cards would you choose to turn to check the ac-
curacy of this rule? Correct: cards A and B.
2. Rule: If a person drinks beer, he/she must be over 18
years old. Which two cards would you choose to turn
to check the accuracy of this rule? Correct: B and A.
3. Rule: If a card shows letter A on one face,
a number 3 is on the opposite face. Which
two cards would you choose to turn to check
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 754
the accuracy of this rule? Correct: A and B.
4. Rule: If a person is over 18 years old, he/she has the
right to vote. Which two cards would you choose to turn
to check the accuracy of this rule? Correct: A and D.
5. Rule: If a person rides a motorcycle, then he/she wears
a helmet. Which two cards would you choose to turn
to check the accuracy of this rule? Correct: C and D.
1. As the Chief Financial Oﬃcer of a corporation, you
are planning to buy new laptops for the workers of
the company. Today, you have to choose between two
types of laptops that are almost identical with regard to
price and the most important capabilities. According to
statistics from trusted sources, type “A” is much more
reliable than type “B”. One of your acquaintances,
however, tells you that the motherboard of the type “A”
laptop he bought burnt out within a month and he lost
a signiﬁcant amount of data. As for type “B”, none
of your acquaintances have experienced any problems.
You do not have time for gathering more information.
Which type of laptop will you buy?
(a) Deﬁnitely type A
(b) Probably type A
(c) Probably type B
(d) Deﬁnitely type B
2. Professor Kellan, the director of a teacher preparation
program, was designing a new course in human devel-
opment and needed to select a textbook for the new
course. She had narrowed her decision down to one of
two textbooks: one published by Pearson and the other
published by McGraw. Professor Kellan belonged to
several professional organizations that provided Web-
based forums for its members to share infor mation about
curricular issues. Each of the forums had a textbook
evaluation section, and the websites unanimously rated
the McGraw textbook as the better choice in every cat-
egory rated. Categories evaluated included quality of
the writing, among others. Just before Professor Kel-
lan was about to place the order for the McGraw book,
however, she asked an experienced colleague for her
opinion about the textbooks. Her colleague reported
that she preferred the Pearson book. What do you think
Professor Kellan should do?
(a) Should deﬁnitely use the Pearson textbook
(b) Should probably use the Pearson textbook
(c) Should probably use the McGraw textbook
(d) Should deﬁnitely use the McGraw textbook
3. The Caldwells had long ago decided that when it was
time to replace their car they would get what they
called “one of those solid, safety-conscious, built-to-
last Swedish” cars — either a Volvo or a Saab. When
the time to buy came, the Caldwells found that both
Volvos and Saabs were expensive, but they decided to
stick with their decision and to do some research on
whether to buy a Volvo or a Saab. They got a copy of
Consumer Reports and there they found that the con-
sensus of the experts was that both cars were very sound
mechanically, although the Volvo was felt to be slightly
superior on some dimensions. They also found that
the readers of Consumer Reports who owned a Volvo
reported having somewhat fewer mechanical problems
than owners of Saabs. They were about to go and strike
a bargain with the Volvo dealer when Mr. Caldwell re-
membered that they had two friends who owned a Saab
and one who owned a Volvo. Mr. Caldwell called up
the friends. Both Saab owners reported having had a
few mechanical problems but nothing major. The Volvo
owner exploded when asked how he liked his car. “First
that fancy fuel injection computer thing went out: $400
bucks. Next I started having trouble with the rear end.
Had to replace it. Then the transmission and the brakes.
I ﬁnally sold it after 3 years at a big loss.” What do you
think the Caldwells should do?
(a) They should deﬁnitely buy the Saab.
(b) They should probably buy the Saab.
(c) They should probably buy the Volvo.
(d) They should deﬁnitely buy the Volvo.
1. When playing slot machines, people win something 1
out of every 10 times. Julie, however, has just won on
her ﬁrst three plays. What are her chances of winning
the next time she plays?
____ out of _____ (Correct: 1 out of 10).
Judgment and Decision Making, Vol. 15, No. 5, September 2020 Measures of cognitive reﬂection 755
2. Imagine that we are tossing a fair coin (a coin that has
a 50/50 chance of coming up heads or tails) and it has
just come up heads 5 times in a row. For the 6th toss do
you think that:
(a) It is more likely that tails will come up than heads.
(b) It is more likely that heads will come up than tails.
(c) Heads and tails are equally probable on the sixth
3. The coin was tossed ﬁve times, but you were not present.
You asked acquaintances what the order of the heads
and tails was. Dinko told you that the order was “head-
head-head-head-head”, and Vinko that the order was
“tail-tail-head-tail-head”? Who do you think is more
likely to tell the truth?
(c) It is equally likely that they are both telling the
4. People typically have a 50% chance of having a male
and a 50% chance of having a female child. However,
Ilija and Ivana currently have four daughters and are
expecting their ﬁfth child. What is the probability that
Ivana will give birth to a son?
(a) Less than 50%
(b) 50% (correct)
(c) More than 50%
5. Four babies were born in one hospital today. As
usual, two local newspapers reported this news. “Daily
Events” newpaper reported that the order of births was
“Boy - Boy - Boy - Boy”, while “World in Your Hand”
newspaper reported that the order was “Girl - Boy -
Boy - Girl”. Only one of these two sources reported
accurate information. What is the probability that the
order reported by the “Daily Events” is correct?
(a) Less than 50%
(b) 50% (correct)
(c) More than 50%
Availability bias. Which cause of death is more likely?
1. Suicide (less likely) vs. Diabetes
2. Homicide (less likely) vs. Diabetes
3. Commercial airplane crash (less likely) vs. Bicycle-
4. Shark attack (less likely) vs. Hornet, wasp or bee bite
Appendix B: Fit indices of CFA analyses test
appropriateness of one-factor solutions of our
𝜒2df CFI TLI RMSEA SRMR NEstimator
CRT 36.35 35 1 1 .01 .03 506 DWLS
BBS 10.54∗∗ 2 .99 .98 .09 .04 506 DWLS
NUM 0.27 2 1 1 .00 .01 506 DWLS
VR 1.43 2 1 1 .00 .02 506 DWLS
AOT 261.34∗∗ 90 .87 .85 .06 .05 469 ML
BRN 6.19 5 1 1 .03 .04 253 DWLS
FCS 5.21 5 1 1 .01 .04 253 DWLS
CBR Just 3 variables, i.e., perfect ﬁt
GF 5.16 5 1 .99 .01 .05 253 DWLS
AV 12.00∗∗ 2 .92 .77 .14 .09 253 DWLS
AV + 0.07 1 1 1 .00 .00 253 DWLS
+after allowing the ﬁrst two items to covary as they are both
related to diabetes.
Appendix C. “Lureness” of our CRT items.