Current Biology

MagazineA

Visual bias
EA
Model coefficients (β)
0B
3010105–

5–

4–

Novel face

–

3–

2–

2

∗∗n.s.

–.5––

0–

1

2

34

Familiarized face–

0–

50

–

4

––

3

2Fear––

1

10 30––

00

Emotional facial expressions are thought
to have evolved because they play a
crucial role in species’ survival. From
infancy, humans develop dedicatedneural circuits [1] to exhibit and recognize
a variety of facial expressions [2]. But
there is increasing evidence that culturespecifies when and how certain emotions
can be expressed — social norms — andthat the mature perceptual mechanisms
used to transmit and decode the visual
information from emotional signals differ
between Western and Eastern adults[3–5]. Specifically, the mouth is more
informative for transmitting emotionalsignals in Westerners and the eye region
for Easterners [4], generating culturespecific fixation biases towards thesefeatures [5]. During development, it isrecognized that cultural differences canbe observed at the level of emotional
reactivity and regulation [6], and to theculturally dominant modes of attention[7]. Nonetheless, to our knowledge nostudy has explored whether culture
shapes the processing of facial
emotional signals early in development.
The data we report here show that, by
7 months, infants from both culturesvisually discriminate facial expressions ofemotion by relying on culturally distinct
fixation strategies, resembling thoseused by the adults from the environment
in which they develop [5].
We used a visual discrimination
paradigm, based on the principles offamiliarization and novelty preference,on 7 month-old Western Caucasian(WC, born and raised in the UK;
N = 77) and East Asian (EA, born and311–,

Happy : own-raceHappy : other-raceFear : own-raceFear : other-race

Fear

––

Elena Geangu , Hiroko Ichikawa
Junpeng Lao5,9, So Kanazawa6,
Masami K. Yamaguchi2,
Roberto Caldara5,10,*,and Chiara Turati7,8,10

Viewing duration bias

D30

1

Happy

2,3,4,96

C

4

1,9

Difference mapWC–

Culture shapes
7-month-olds’
perceptual
strategies indiscriminating facial
expressions ofemotion

EA observers

WC observers–Correspondence

510 30HappyFigure 1. Testing cultural differences in emotional face exploration and discrimination.
(A) The spatial modelling of the fixation patterns was conducted using iMap4, a data-driven framework for statistical fixation mapping (8] (see Supplemental Information for more details). Pixel-wise
ANOVA on the model coefficients of the linear mixed model (Eq. s1 in Supplemental Information)
revealed a significant main effect of Culture on the mouth and the nose area and a significant main
effect of Culture around the eye region. By performing a linear contrast between WC and EA infants,
our data show that WC infants fixated more on the mouth compared to EAs, whereas EA infants
showed a bias towards the eye region and displayed longer fixation duration on the eye than WCs(detail statistical values are reported in Supplemental Information). (B–D) To disentangle the effect ofviewing duration of the test phase, we applied a multivariate generalized linear model and a novel
visualization of the effect on a two-dimensional surface. Linear contrast on the multivariate generalized linear model coefficients (Eq. s2 in Supplemental Information) revealed the effect of facial
expression during the test phase (B). Infants showed a strong fixation bias towards fearful comparedto happy faces, looking longer at the fearful (mean viewing duration = 1.95s [1.853, 2.051]) than at
the happy faces (mean viewing duration = 1.68s [1.589, 1.772]; F (1, 596) = 16.00, p = 7.119e-05;
brackets show bootstrapped 95% confidence interval). This bias for facial expressions is presented
as a 2D surface with the estimated density peak show in the white square (more details in SI).
Moreover, we found a main effect of familiarity (C), as infants fixated longer on the novel expression(mean viewing duration = 1.90s [1.807, 2.000]) compared to the familiarized expression (mean viewing duration = 1.73s [1.633, 1.831]; F (1, 596) = 6.61, p = 0.0104). We also found a significant culture
difference in the fearful face bias (F (1, 596) = 3.95, p = 0.0473), whereas the culture difference inthe novel face bias is not significant (F (1, 596) = 1.12, p = 0.2691). Importantly, as shown in (D), theviewing bias towards fearful expressions is reduced when the infants were familiarized with fearfulfaces, thus explaining the main effect of familiarity. Infants familiarized with own-race fearful faces
showed the least viewing bias towards fear compared to the other three conditions (F (3, 596) =3.09, p = 0.0266). Error bars report 95% bootstrapped CI.

raised in Japan; N = 76) infants, while
tracking their eye movements. In thefamiliarization phase, infants werepresented with one emotional expression(fear or happiness) across different facial
identities; this was followed in the test
phase by the presentation of pairs offaces displaying the familiarized emotion
alongside the novel one (Figure S1A,B
in the Supplemental Information). Halfof the infants were familiarized to fear,
the other half to happiness. The raceof the faces (own versus other) waskept constant across familiarization andtest phases and manipulated between

participants. The visual preference during
the test phase indicates infants’ ability todiscriminate between facial expressionsof emotion. To determine the perceptualstrategies infants used to accomplish
the discrimination task, we tracked
infants’ eye movements during both thefamiliarization and test phases.
A data driven analysis method basedon robust non-parametric statistics [8]revealed that, during the familiarization
phase (Figure S1D), WC infants fixatedsignificantly more on the mouthcompared to EA infants, who showed asignificant bias towards the eye region

Current Biology 26, R641–R666, July 25, 2016 © 2016 Elsevier Ltd. R663

Current Biology

Magazineand displayed longer fixations on the eyes
than WCs (Figure 1A). Crucially, the facial
expression and the race of the faces did
not alter infants’ fixation strategies. These
cultural differences in eye movements
are in line with those previously reported
in adults for emotional recognition [5],and distinct from those typically foundwhen infants [9], children [10], and older
adults extract face identity information. To
then assess whether infants discriminate
between emotional facial expressions
during the test phase, we applied a
multivariate generalized linear modeland novel two-dimensional surface
visualization (Figure 1B–D). All infants
looked longer towards fearful comparedto happy faces (Figure 1B). Also, as aresult of familiarization, they fixated longer
the novel compared to the familiarizedemotional expression (Figure 1C),
which indicates an effective expression
discrimination. The viewing bias towards
the fearful expression (longer fixationduration) was reduced when the infants
were familiarized with own-race fearfulfaces (Figure 1D), while, importantly, theculturally specific perceptual strategies
remained unchanged. In addition, weapplied unsupervised clustering using aGaussian mixture model to quantify thefixation strategy between familiarizationand test phases (see SupplementalInformation). Importantly, analysis of therelation between the fixation patterns
during familiarization and test phases
showed that the cultural fixation bias
is consistently present at the individuallevel in infant observers (Figure S2B).
The strength of this fixation bias wasweaker in WC infants after familiarization
to fearful faces, compared to the EA
infants, who persistently fixated the eyeregion regardless of task demands suchas exploration and discrimination ofemotional facial expressions (Figure S2C).
The acquisition of effective
representations in infants fordiscriminating facial expressions isbased on an optimal combinationof neural systems dedicated to theprocessing of emotion and theirrefinement through experience [1].
Our results show that culture-specificearly experience can determine theinformation intake for the biologicalneural circuitry. Eastern and Western
7-month-old infants effectively
discriminate happy and fearful faces,
but the pattern of eye movements
used to reach this developmental
R664

milestone differ. These culturally-specificinformation sampling biases resemble
the previously reported eye movement
fixation mappings in adults [5] with
the Easterners focusing more toward
the eye region while processing facial
expressions and Westerns focusing
more on the mouth [4].
These differences in the informativevalue of face areas during emotion
communication are also reflected in theuse of emoticons, with Eastern adults
reporting predominantly changes in
expressions through the eyes ^_^ T_T(happy and sad) and for the Westerners
through the mouth respectively, :-) :-(. The
cultural environment, such as parental
practices, may also contribute in several
ways to the development of thesescanpath differences. Asian mothers use
less emotional expressivity and more
non-direct body contact stimulation thanthe Western ones [6], which could lead to
Asian infants’ increased attention to theculturally-specific facial emotional signals
in the eye region. This attentional strategy
may be further reinforced by otherculturally driven parental practices forpromoting learning throughout childhood,consolidating into the diverse modes ofattention observed in older children andadults [7]. Overall, our findings show thatculture heavily shapes the developmentof perceptual strategies used to process
biologically-relevant social signals froman early stage in life.
SUPPLEMENTAL INFORMATION
Supplemental Information includes experimental procedures and two figures and can befound with this article online at http://dx.doi.
org/10.1016/j.cub.2016.05.072.
AUTHOR CONTRIBUTIONS
R.C. originated the idea of the study and acted
as corresponding author. C.T. put together andcoordinated the research group. The experiments were designed by C.T., E.G., H.I., M.K.Y.
and R.C.. E.G. and H.I. generated the stimuli,
implemented and performed the experiments,
and collaborated in data analyses. Data werecollected in the E.G. and M.K.Y., S.K. laboratories. J.L. performed the analyses, under thesupervision of R.C.. The paper was written by
E.G., H.I., J.L., R.C., and C.T.
ACKNOWLEDGMENTS
We are grateful to all families who agreed
to participate in this study. This research
was supported by Great Britain Sasakawa

Current Biology 26, R641–R666, July 25, 2016

Foundation (Grant No. 4454) to E.G.,
Grant-in-Aid for Scientific Research byJSPS Research Fellowships for Young
Scientists (No. 24 7809) to H.I., a European
Research Council Starting Grant (ODMIR No.
241176) awarded to C.T. and a grant fromthe Swiss National Science Foundation (No.
100014_138627) awarded to R.C.
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1
Department of Psychology, Lancaster
University, Bailrigg, Lancaster LA1 4YF, UK.
2
Department of Psychology, Chuo University,Hachioji-city, Tokyo, 192–0393, Japan.
3
Japan Society for the Promotion of Science,
Chiyoda-ku, Tokyo, 102–0083, Japan. 4Current
affiliation: Faculty of Science and Technology,
Tokyo University of Science, Yamazaki 2641,
Noda, 278-8510, Chiba, Japan. 5Eye and Brain
Mapping Laboratory (iBMLab), Department ofPsychology, University of Fribourg, Faucigny 2,1700 Fribourg, Switzerland. 6Departmentof Psychology, Japan Women’s University,Kawasaki, Kanagawa, 214– 8565, Japan.
7
Department of Psychology, University of
Milano-Bicocca, Piazza dell’Ateneo Nuovo, 1,20126 Milano, Italy. 8NeuroMi, Milan Center for
Neuroscience, Milano, Italy.
9Co-first authors.
10
Co-last authors.
*E-mail: roberto.caldara@unifr.ch