, 1234 (2010);
, et al.Akira Miyake
Classroom Study of Values Affirmation
Reducing the Gender Achievement Gap in College Science: A
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The balance of inertia and gravity yields a
prediction for the lapping frequency of other
felines. Assuming isometry within the Felidae
family (i.e., that lapping height H scales linearly
with tongue width R and animal mass M scales
as R3), the finding that Fr* is of order one trans-
lates to the prediction f ∼ R–1/2∼ M–1/6. Isom-
etry or marginally positive allomety among the
Felidae has been demonstrated forskull (20, 21)
and limb bones (22). Although variability by
function can lead to departures from isometry in
in the Felidae (23, 24) only minimally affect the
predicted scaling f ∼ M–1/6. We tested this –1/6
frequency for eight species of felines, from vid-
eos acquired at the Zoo New England or avail-
observed to decrease with animal mass as f =
4.6 M–0.181 T 0.024( f in s−1, M in kg) (Fig. 4C),
close to the predicted M–1/6. This close agree-
ment suggests that the domestic cat’s inertia- and
The lapping of F. catus is part of a wider
inertia, sometimes referred to as Froude mech-
the Basilisk lizard depends on the gravity-driven
collapse of the air cavity it creates upon slapping
the lizard’s leg penetrates the surface depends
on the Froude number, which in turn prescribes
number is also relevant to swimming, for exam-
ple, setting the maximum practical swimming
motion. In thisrespect,it is interesting to note that
the transition from trot to gallop obeys nearly the
samescaling offrequency withmassaslapping,
f = 4.5 M−0.14( f in s−1, M in kg) (27).
The subtle use of the tongue in the drinking
process of F. catus is remarkable, given the
movement in the absence of rigid components is
a common feature of muscular hydrostats, which
inaddition to tongues include elephanttrunksand
octopus arms (28, 29). The functional diversity
and high compliance of these structures continue
to inspire the design of soft robots (29), and a
fundamental understanding of their functionality
can lead to new design concepts and is essential
to inform biomechanical models (29, 30).
References and Notes
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material on Science Online.
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Biol. Cybern. 67, 403 (1992).
31. All research with animals complied with and was approved
by MIT's Animal Rights Committee. We thank J. Piazza
and the staff at the Zoo New England for help with filming
felines; M. Rock, A. Kennedy, and the Massachusetts Society
for the Prevention of Cruelty to Animals (MSPCA) for help
with filming domestic cats; G. McKinley for use of his
FiSER stage; A. Crompton, A. Thexton, W. Kier, J. Bales,
J. Bush, B. Andreotti, J. Bico, D. Vella, and A. Boudaoud
for discussions and comments; and A. Jones, E. Samaha,
R. Tomas, and W. Jarjoui for technical assistance. S.J.,
P.M.R., and R.S. designed research; S.J., P.M.R., R.S., and
J.M.A. performed experiments and analyzed data; S.J.,
J.M.A., and R.S. developed scalings and theory; P.M.R.,
R.S., S.J., and J.M.A. wrote the paper.
Supporting Online Material
Materials and Methods
Movies S1 to S3
21 July 2010; accepted 20 October 2010
Reducing the Gender Achievement
Gap in College Science: A Classroom
Study of Values Affirmation
Akira Miyake,1* Lauren E. Kost-Smith,2Noah D. Finkelstein,2Steven J. Pollock,2
Geoffrey L. Cohen,3Tiffany A. Ito1
In many science, technology, engineering, and mathematics disciplines, women are outperformed
by men in test scores, jeopardizing their success in science-oriented courses and careers. The
current study tested the effectiveness of a psychological intervention, called values affirmation,
in reducing the gender achievement gap in a college-level introductory physics class. In this
randomized double-blind study, 399 students either wrote about their most important values or
not, twice at the beginning of the 15-week course. Values affirmation reduced the male-female
performance and learning difference substantially and elevated women's modal grades from the
C to B range. Benefits were strongest for women who tended to endorse the stereotype that men do
better than women in physics. A brief psychological intervention may be a promising way to
address the gender gap in science performance and learning.
en in science, technology, engineering, and
mathematics (STEM) disciplines has long
Ph.D.s in physical sciences, 25% in mathematics
and computer science, and 20% in engineering in
the United States (3). Although women made up
percentage of women in lucrative technical pro-
fessions, such as “computer and mathematical
occupations” and “architecture and engineering oc-
cupations,” reached only 25% and 14%, respec-
tively (4). Similar underrepresentation of women
in STEM-related professions is also evident in
other parts of the world (5).
The gender gap in STEM disciplines goes
beyond the limited representation of women. In
college physics—the field studied in the present
investigation—women earn lower exam grades
tual mastery (6, 7). Students’ prior background
and preparation in mathematicsand physics,iden-
1Department of Psychology and Neuroscience, University of
University of Colorado at Boulder, Boulder, CO, USA.3School of
Education, Department of Psychology, and Graduate School of
Business, Stanford University, Palo Alto, CA, USA.
*To whom correspondence should be addressed. E-mail:
26 NOVEMBER 2010VOL 330
on March 6, 2011
tified as a major contributor to performance in
our institution, the University of Colorado, but
background and preparation do not fully account
for the gap (9).
Because gender achievement gaps have im-
attempts have been made to reduce them. For
example, in physics, interactive techniques such
as peer instruction (10), where students discuss
during lectures, and curricular materials, such as
rich problems (12), can reduce the gender gap in
college physics classrooms (13). Larger-scale at-
tempts to reduce the gendergap in physics include
restructuring the entire physics course (7, 14, 15)
or introducing mentoring programs focused on
gender gaps, interventions in science education
have not taken into account social-psychological
and cognitive processes that lead to gender dif-
ferences in performance and learning. One such
process involves psychological threat tied to the
(17). For example, women’s performance on dif-
ficult math and science tests can suffer insofar as
they worry that their poor performance could
be seen to confirm a negative gender stereotype
(18, 19). Although such identity threat has been
shown to affect performance in lab experiments
and classrooms (20, 21), attempts to reduce iden-
tity threat in authentic classroom contexts have
been limited (22, 23).
Here, we report a large-scale classroom study
that tested the effectiveness of a theoretically
affirmation (24, 25), in reducing the gender gap in
exam scores and in a standardized test of con-
complementary yet comparatively simple strategy
to address gender differences in performance and
learning in college science classrooms. A novel
feature of this study is that it provides a formal
Physics is a challenging subject for many
and textbooks and demonstrating understanding
on exams put substantial pressure on students.
women at math and science (26), such pressure
can prove more severe for women than men,
might be valid and worry that it could apply or be
applied to them (20, 27). Values affirmation, in
which people reflect on self-defining values, can
buffer people against such psychological threat.
environment, people reestablish a perception of
personal integrity and worth, which in turn can
coping effectively (24, 25, 28). Indeed, lab studies
(29) and improve the performance of stereotype-
threatened individuals (30).
The values-affirmation intervention used in
this study involves writing about personally impor-
the subject matter of the course. Nevertheless, it
has been found effective in improving the grades
of ethnic minority middle-school students and
closing the racial achievement gap (23). More-
over, this benefit persisted in a 2-year follow-up
would reduce the gender achievementgapina 15-
week introductory physics course for STEM
majors. Because the course had already imple-
mented pedagogical practices aimed at lessening
gender gaps (10, 11), this setup provided a strong
test of the effectiveness of values affirmation to
further reduce the gap. Moreover, compared to the
African-American middle-school students in pre-
students wererelatively high-achieving (takingcol-
lege physics and most planning to be STEM ma-
In this randomized double-blind study, 399
ly assigned to either the values-affirmation group
or the control group (32). Students in the affirma-
tion group selected their most important values
from a list (such as relationships with friends and
family or learning or gaining knowledge) and, in
response to structured prompts, wrote about why
Fig. 1. Student performance on two outcome
measures examined in this study as a function of
gender (men versus women) and affirmation con-
dition (values affirmation versus control). (A) The
overall combined exam scores, derived by averag-
(weeks 5, 9, and 14) and the final exam for each
student. (B) The end-of-semester (week 15) score of
the FMCE, a standardized test of conceptual knowl-
learning of basic physics concepts over the course of
the semester. Exam scores are adjusted based on
baseline math performance (SAT/ACT Math scores),
and the end-of-semester FMCE scores are adjusted
based on beginning-of-semester FMCE scores (SOM
text). Error bars represent T1 SE.
Fig. 2. Percentage of students receiving each letter grade (A, B, C, D, and F, combining letter grades
affirmation versus control). The percentage was calculated separately for each values-affirmation con-
dition within each gender.
VOL 330 26 NOVEMBER 2010
on March 6, 2011
these values were important to them. Students in
the control group selected their least important
values from the same list and wrote why these
values might be important to other people. Thus,
both groups wrote about values and their impor-
tance, but the exercise was self-relevant only for
the affirmation group. This 15-min writing exer-
cise was integrated into the class and was given
once in the first recitation of the semester (week
1) and once in an online homework assignment
(week 4) shortly before the first midterm exam
(week 5). Each student was assigned to the same
condition at both administrations. The course in-
structor and teaching assistants were unaware of
assistants and students were unaware of the pur-
survey typically given in the course (week 2),
students also indicated their endorsement of the
stereotype that men perform better than women
The mainoutcome measure was scoresonin-
class exams (three midterms and one final) that
consisted entirely of objective multiple-choice
questions and constituted 75% of the final course
grade. To assess the effect of values affirmation on
nationally normed standardized test of conceptual
physics [the Force and Motion Conceptual Eval-
uation (FMCE)] (33). Historically, men have
substantially outperformed women on exams and
the FMCE (9) in this course. In semesters when
exams are heavily weighted (as in the semester of
gender gap (9).
ance for women who completed the values affir-
mation. Moreover, because people who endorse
negative stereotypes about their group are most
vulnerable to identity threat (20, 27), we expected
the intervention to be particularly beneficial for
women tending to endorse the gender stereotype.
The values-affirmation intervention succeeded
in reducing the gender gap in performance. As
shown in Fig. 1A, men outperformed women in
the control condition on overall exam scores (the
average of the percent correct for the four exams).
However, the gendergap was significantly smaller
in the affirmation condition than in the control
condition, resulting in a significant gender × con-
dition interaction [b = 0.16, t(387) = 3.08, P <
0.01] (34). The effect size for the observed gen-
der gap was substantial in the control condition
(Cohen’s d = 0.93) (F1,387= 36.71, P < 0.01) but
much smaller in the affirmation condition (d =
0.18) (F1,387= 2.35, P = 0.13). Course grades,
based substantially (75%) on the exam scores,
showed a similar pattern [supporting online ma-
terial (SOM) text].
completed shortly before the first midterm exam,
its benefits were not confined to that exam. The
reduction in the gender gap remained evident on
by a significant gender × condition interaction
[b = 0.19, t(387) = 3.45, P < 0.01; affirmation
effect for women, F1,387= 12.49, P < 0.01], even
took place beyond the fourth week of class.
The distribution of final letter grades indicated
improving women's performance from average
(C) to above average (B). As shown in Fig. 2,
women in the two groups differed primarily in the
B-to-C range; more women earned B’s in the af-
more women earned C’s in the control group than
0.04]. There was no such difference in grade dis-
The benefit of values affirmation for women
was also observed on the FMCE. It was admin-
istered twice as part of the course, once at the
beginning of the semester (week 1) and once at
the end (week 15), to assess learning of physics
concepts over the semester. Students were ex-
plicitly told that their performance would not
or interactive effect of condition on the beginning-
of-semester score [t’s< 1,NS],there was an effect
at the end of the semester. Figure 1B illustrates the
on the beginning-of-semester scores to isolate ef-
that men improved their FMCE scores more than
women over the semester. In the affirmation con-
dition, however, this gender learning gap entirely
disappeared (d =–0.12) (F1,304= 0.96, P= 0.33),
action [b = 0.12, t(296) = 2.13, P = 0.03]. That
the benefit of affirmation was evidenced on the
end-of-semester FMCE scores with beginning-
of-semester scores controlled suggests that the
intervention facilitated women’s learning of sci-
entific concepts over the semester (SOM text).
men’s exam scores (Fig. 1A), but, unlike the pos-
was not replicated for the end-of-semester FMCE
score (Fig. 1B), and did not change men’s letter
grade distribution (Fig. 2) (35). In contrast, the af-
firmation’s positive effect on women was signifi-
is based more robustly on the affirmation’s pos-
itive impact on women than on its negative im-
pact on men.
Finally, the values affirmation was particular-
ly beneficial for women who tended to endorse
the gender stereotype. This moderation effect is
illustrated in Fig. 3, with the exam (Fig. 3A) and
end-of-semester FMCE (Fig. 3B) data. Although
women as a group did not strongly endorse the
negative gender stereotype (20), even a moderate
level of stereotype endorsement was costly for
women in the control condition, with their exam
scores decreasing as a function of stereotype en-
dorsement [b = –0.50, t(387) = –3.29, P < 0.01]
(Fig. 3A). Affirmation, however, buffered women
againstthisidentity threat,eliminating the negative
scores [b = 0.12, t(387) = 0.94, P = 0.35]. More-
over, among women expressing higher levels of
stereotype endorsement (defined as 0.75 SDs
above the mean here), affirmation improved the
exam scores relative to the control condition
scores were little affected by stereotype endorse-
Fig. 3. Student performance on two outcome measures examined in this study as a function of gender
endorsement. (A) The overall combined exam scores, computed by averaging the percentage scores for
the four exams. (B) The end-of-semester (week 15) score on the FMCE, a standardized test of conceptual
knowledge in physics (33). Stereotype endorsement, treated as a continuous variable in our statistical
disagree”to “strongly agree.” The level of stereotype endorsement plotted in the graph was standardized
in the graph are represented by T0.75 SD of the grand mean (SOM text). Error bars represent T1 SE.
26 NOVEMBER 2010 VOL 330
on March 6, 2011
b = –0.07, t(387) = –0.92, P = 0.36, for the con-
trol condition].These differentialpatterns for men
and women resulted in a gender × condition ×
stereotype endorsement interaction [b = 0.16,
t(387) = 2.74, P < 0.01].
A similar three-wayinteraction was found for
the FMCE scores (Fig. 3B) [b = 0.15, t(296) =
2.45, P = 0.02]. Among women, there was a
negative relationship between stereotype endorse-
ment and end-of-semester FMCE scores in the
control condition [b = –0.39, t(296) = –2.55, P =
with higher levels of stereotype endorsement, the
end-of-semester FMCE scores were higher in the
[t(115) = 3.01, P < 0.01]. No such relationship
was observed for men in either the control condi-
tion [b = –0.13, t(296) = –1.33, P = 0.18] or the
affirmation condition [b = –0.10, t(296) = –1.41,
P = 0.16].
mation is a promising intervention that can help
reduce the gender achievement gap in physics.
Although the intervention was brief and did not
directly concern the course material, it nonethe-
less provided a meaningful boost for women—
stereotype—on two objective measures: in-class
multiple-choice exams and a standardized test of
conceptual mastery (FMCE). Moreover, the re-
sults on the end-of-semester FMCE provide evi-
dence that identity threat and affirmation affect
the learning of scientific concepts, not just per-
formance (SOM text). After controlling for prior
background(prior SAT/ACTMath orbeginning-
of-semester FMCE scores), the affirmation closed
the “residual” gender gap on in-class exam scores
by approximately 61% and entirely eliminated the
gap on the FCME. Although further efforts must
aim to close the gap in prior preparation, the cur-
rent results are promising in demonstrating that a
brief psychological intervention can help close the
residual gap, a problem of long-standing concern
in science (9).
The introductory physics class we investi-
gated was intended for STEM majors who have
lege and are motivated to do well in the course.
women who are relatively identified with and ac-
complished in science, a substantial gender gap
be reduced with a values-affirmation intervention.
on instructional methods, the current results high-
light the importance of social-psychological fac-
tors. One virtue of the affirmation is that it can
be combined with instructional approaches that
show promise in closing the gender gap, such as
present course (10). However, there is no reason
to situations in which such instructional supports
are already in place, given that the intervention was
successful in reducing racial achievement differ-
classrooms (23, 31). Of course, even here, there
were structural opportunities for learning in the
without such basic support, the efficacy of any
Another virtue of the values-affirmation inter-
vention is that it is not tied to a specific discipline.
The psychological phenomenon that the interven-
in other STEM disciplines where the underrepre-
sentation and underperformance of women have
broad applicability in many STEM disciplines.
Finally,the benefits of the affirmation may be
present course. The experience of lower identity
science course, may encourage affirmed women
More generally, the cumulative consequences of
early performance—small differences at an early
stage can get magnified over time—help explain
how relatively brief interventions, when given
early in a threatening environment, can have long-
term effects. This snowballing effect may be par-
ticularly important in science, where subsequent
edge, making it increasingly difficult to catch up
and enter a discipline later. Therefore, it may be
introductory physics. These courses are required
for STEM majors, and performance in them can
set long-term academic and career trajectories.
Reducing the gender gap at gateways could not
only benefit women’s performance in the short
in a scientific major and career path in STEM
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34. The effect of values affirmation on exam scores and end-
of-semester FMCE scores was tested in regression models
in which the outcome measures were regressed on
gender, affirmation condition, and the gender ×
condition interaction. SAT/ACT Math scores were
controlled for in the analysis of exam scores, and
beginning-of-semester FMCE scores were controlled
for in the analysis of end-of-semester FMCE scores.
All b weights reported in this article are standardized
weights. The full regression models are described in
35. This unexpected finding for men's in-class exam scores is
discussed in more detail in the SOM. In addition to the
mixed evidence summarized here, this negative affirma-
tion effect on men's exam scores was not significant
when the analysis was conducted with the beginning-of-
semester FMCE scores (instead of SAT/ACT Math scores) as
the covariate (S22).
36. We are grateful to course instructor M. Dubson, the
course teaching assistants, and the student participants.
We also thank L. Newnes and N. Golaszewski for
invaluable assistance with data collection and C. Judd
and B. Park for their statistical advice. This research
was supported by NSF grant DRL0910373.
Supporting Online Material
Materials and Methods
References and Notes
3 August 2010; accepted 25 October 2010
VOL 330 26 NOVEMBER 2010
on March 6, 2011