When East meets West: Blindspots diversity in eye movements for faces

When East meets West: Blindspots diversity in eye movements for faces
Journal of Eye Movement Research
5(2):5, 1-12
When East meets West:
gaze-contingent Blindspots abolish cultural
diversity in eye movements for faces
Sébastien Miellet
University of Fribourg
Lingnan He
Xinyue Zhou
Sun Yat-Sen University
Sun Yat-Sen University
Junpeng Lao
Roberto Caldara
University of Glasgow
University of Fribourg
Culture impacts on how people sample visual information for face processing. Westerners
deploy fixations towards the eyes and the mouth to achieve face recognition. In contrast,
Easterners reach equal performance by deploying more central fixations, suggesting an
effective extrafoveal information use. However, this hypothesis has not been yet directly
investigated, i.e. by providing only extrafoveal information to both groups of observers.
We used a parametric gaze-contingent technique dynamically masking central vision - the
Blindspot – with Western and Eastern observers during face recognition. Westerners shifted progressively towards the typical Eastern central fixation pattern with larger Blindspots,
whereas Easterners were insensitive to the Blindspots. These observations clearly show
that Easterners preferentially sample information extrafoveally for faces. Conversely, the
Western data also show that culturally-dependent visuo-motor strategies can flexibly adjust to constrained visual situations.
Keywords: Face perception, culture, eye movements, gaze-contingent Blindspot,
extrafoveal processing
stance, Blais et al. (2008) have shown that Western Caucasians (WC) predominantly fixate the eye region during
face recognition whereas East Asians (EA) focus more on
the nose region, yet reach comparable behavioural performance in face recognition (i.e., accuracy and response
time) and categorization by race. This finding shows that
face processing can be achieved with diverse fundamental scanpaths. Moreover, the cultural biases in visual
information sampling as revealed by scanpath 1- extend
to the identification of various biological (sheep) and
non-biological (greebles) categories of visually homogeneous stimuli (Kelly et al., 2010); 2- are present as early
as 7 years old even if they intensify with age (Kelly et al.,
2011); 3- do not generalize to other tasks such as animal
search in natural visual scenes (Miellet, Zhou, He, Rodger & Caldara, 2010).
Introduction
Eye movement strategies deployed by humans to
identify conspecifics are not universal. Since Yarbus
(1965), many studies persistently showed, with Western
observers, that fixations follow a systematic triangular
sequence sampling the eyes and mouth over the course of
face identification (e.g., Althoff & Cohen, 1999; Groner,
Walder & Groner, 1984; Henderson, Williams & Falk,
2005). However, recent studies showed the deployment
of central fixations in Easterners (Blais, Jack, Scheepers,
Fiset & Caldara, 2008; Kelly, Liu, Rodger, Miellet, Ge &
Caldara, 2011; Kelly, Miellet & Caldara, 2010; Kita,
Gunji, Sakihara, Inagaki, Kaga, Nakagawa & Hosokawa,
2010; Rodger, Kelly, Blais & Caldara, 2010). For in-
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Miellet, S., He, L., Zhou, X., Lao, J. & Caldara, R. (2012)
Blindspots abolish cultural fixation bias for faces
The central fixation pattern observed in Easterners is
puzzling because a very abundant literature on face
recognition robustly showed, in Westerners, that the critical information for face recognition is located in the eyes
and partially the mouth, but not the nose (testing Western
Caucasian observers in the recognition of Western Caucasian faces: e.g., Davie, Ellis & Shepherd, 1977; Fraser,
Craig & Parker, 1990; Haig, 1986; with response classification techniques in normal healthy adults: e.g., Gosselin
& Schyns, 2001; Schyns, Bonnar & Gosselin, 2002; and
brain damaged patients: Caldara, Schyns, Mayer, Smith,
Gosselin & Rossion, 2005; with computational modelling: e.g., Rowley, Baluja & Kanade, 1998; Viola &
Jones, 2004). We recently addressed this apparent paradox with the Spotlight technique, by restricting the visual
information available to observers with Gaussian apertures, sized 2°, 5° or 8°, and dynamically centered on
WCs’ and EAs’ fixations (Caldara, Zhou & Miellet,
2010). Crucially, in the 2° and 5° conditions, the Spolight
apertures covered an entire eye, but the eyes and the
mouth were not visible when fixating the nose. By contrast, when observers fixated the nose in the 8° condition,
the mouth and eyes could be simultaneously viewed.
Analysis of fixations strategies showed that the differences reported by Blais et al. (2008) were abolished in
the restrictive 2° and 5° conditions with both populations
of observers predominantly directing their fixations to the
eye region. However, in the 8° condition, when the eyes
were visible while fixating the centre of the face, the EA
participants reverted to their preferred central landing
position. These data suggest that the facial information
required to accurately individuate conspecifics is invariant across human beings, but the strategies used to extract
this information are likely to be flexible and might be
modulated by culture. Therefore, one of the most plausible explanations accounting for EA fixation strategies in
face identification would consist of a better use of extrafoveal information in this culture. EA adults fixate the
nose region when viewing faces, but actually might exploit the eye region extrafoveally to recognize faces.
thought to be collectivistic, emphasizing the importance
of the group over individual goals. This striking contrast
in the societal organizations implies that people in different cultures have fundamentally a different construal of
the self and others. This would impact not only in human
social interactions, but also critically on the way people
afford their (visual) environment (Chiu, 1972; Hsu, 1981;
Ji, Zhang & Nisbett, 2005; Markus & Kitayama, 1991;
Nisbett, 2003; Triandis, 1989). Westerners would favor
the perception and attention to focal objects rather than a
context, whereas Easterners would focus more on the
relationship between objects. These perceptual biases
would be also supported by perceptual strategies of a
different nature. Westerners would rely on analytical perceptual processes to adapt to the visual world, whereas
Easterners would rely on holistic/global perceptual processes (Nisbett & Miyamoto, 2005). This view has been
supported by abundant empirical evidence including:
scene perception (e.g., Miyamoto, Nisbett, & Masuda,
2006) and description (e.g., Masuda & Nisbett, 2001),
perceptual categorization (Norenzayan, Smith, Kim, &
Nisbett, 2002), and eye movements during visual scene
processing (Chua, Boland & Nisbett, 2005). It is worth
noting that the cultural variation in eye movements during scene perception is highly controversial. While Chua
et al. (2005) observed some effects of culture on recognition performance as well as on eye-fixation patterns; Evans, Rotello, Li, and Rayner (2009), Rayner, Castelhano
and Yang (2009), and Rayner, Li, Williams, Cave and
Well (2007) did not find any consistent difference between the two cultural groups. In short, there is a “causal
chain running from social structure to social practice to
attention and perception to cognition” (Nisbett and Masuda, 2003).
From these previous results, Miellet et al. (2010)
aimed, in a recent study, to address a central question: Is
there a mandatory, general perceptual bias modulating
extrafoveal information use across cultures? In other
words, do EA observers rely more on extrafoveal information than WC observers? To directly address these
questions, Miellet et al. (2010) used a gaze-contingent
technique designed to dynamically obscure central vision
with parametric Blindspots, permitting only extrafoveal
information use. The task required the detection and subsequent identification of animals in natural visual scenes.
In order to finely assess the central versus extrafoveal
influence of visual information, they parametrically manipulated both the Blindspot size (Natural-vision, 2°, 5°
One of the most influential, despite arguable, view in
the cultural field assumes that the organization of the
social systems, in which people develop and live, leads to
the diversity in cultural perceptual strategies (for a review
see Nisbett & Masuda, 2003; Nisbett & Miyamoto,
2005). In this framework, Western societies are thought
to be individualistic, encouraging the pursuit of personal
goals (Triandis, 1995). By contrast, Eastern societies are
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Blindspots abolish cultural fixation bias for faces
or 8°) and the size of the targets (absent, 2°, 5° or 8°).
Finally, they used an unbiased, data driven approach
based on fixation maps (iMap: Caldara & Miellet, 2011);
and introduced novel spatio-temporal analyses in order to
finely characterize the dynamics of scene exploration in
both groups of observers. The Blindspot is based on a
gaze-contingent technique introduced by Rayner and
Bertera (1979) and was originally called moving mask.
This technique has also been referred as artificial scotoma, simulated scotoma or foveal mask, and has been used
in a variety of paradigms: reading (Fine & Rubin, 1999;
Rayner & Bertera, 1979, Rayner, Inhoff, Morrison,
Slowiaczek & Bertera, 1981), search (Bertera, 1988;
Bertera & Rayner, 2000; Cornelissen, Bruin, &
Kooijman, 2005; Murphy & Foley-Fisher, 1989; van
Diepen & d'Ydewalle, 2003; van Diepen, Ruelens &
d'Ydewalle, 1999), visual learning (Castelhano & Henderson, 2008), object identification (Henderson,
McClure, Pierce & Schrock, 1997). This gaze-contingent
technique has proven very beneficial to investigate the
visual processing of peripheral versus central retinal inputs. In Miellet et al.’s study (2010), both groups of observers, Eastern and Western, showed comparable animal
identification performance, which decreased as a function
of the Blindspot sizes. Importantly, dynamic analysis of
the exploration pathways revealed identical oculomotor
strategies for both groups of observers during animal
search in scenes. This result indicates that there is no
such thing as a general (task independent) perceptual bias
modulating extrafoveal information use across cultures.
ric manipulation of the Blindspot size (Natural-vision, 2°,
5° and 8° in order to permit a direct comparison with
Caldara et al., 2010 and Miellet et al., 2010 results). If,
for face recognition, EA observers rely preferentially on
extrafoveally extracted diagnostic features (eyes/mouth)
sampled from central fixation locations (on the centre of
the face), then the central Blindspot should not alter this
extrafoveal extraction and their fixation pattern should
not be heavily impacted by the parametric manipulation
of the Blindspot size. In contrast, if WC observers preferentially sample foveally the diagnostic features in natural
vision, then the Blindspot will impede this sampling
strategy and their fixation pattern should progressively
shift, as the Blindspot size increases, from the eyes and
mouth in natural vision towards the optimal location for
extrafoveal sampling of the diagnostic features i.e. the
centre of the face. Indeed, the Blindspot precludes the
sampling of the diagnostic facial features that are directly
fixated. For large Blindspots, the observers would mask
the diagnostic features if they fixate them. The diagnostic
features are the features that the observers need to sample
in order to achieve face recognition (eyes and mouth, see
for instance Caldara et al., 2010; Davies, Ellis & Shepherd, 1977; Gosselin & Schyns, 2001; Viola &
Jones, 2004). Therefore, we expect that, with large Blindspots, observers will choose a fixation location that allows them to process the diagnostic features without directly fixating them. The middle of the face is the most
effective location for sampling extrafoveally eyes and
mouth information while minimizing eye movements.
This raises an important question. Do the cultural differences consistently observed on the gaze scanpaths during face recognition reflect differential extrafoveal information use across cultures in this specific, although biologically relevant, task? Indeed, given the discrepancy
between Caldara et al. (2010) and Miellet et al. (2010)
results (Spotlight technique in face recognition and Blindspot technique during search in natural scenes respectively), it might be that there is not such a thing as a cultural
bias in extrafoveal information use or that this bias is
confined to face processing. As mentioned before, a
method of choice to directly tap into central versus extrafoveal processing is the Blindspot technique.
To sum up, we expected to observe, in the naturalvision condition, the well-documented cultural fixation
bias for face recognition (central bias for EA observers
and eyes-mouth bias for the WC observers). A previous
study using the Spotlight technique (Caldara et al., 2010)
showed that a gaze-contingent masking of extrafoveal
information during face recognition induces a “Westernlike” visual information sampling strategy (fixations on
eyes and mouth) among EA observers. Following a similar logic, we hypothesized that the Blindspot technique,
by restricting access to central (foveal) visual information, would lead to an “Eastern-like” strategy (fixations on the centre of the face) among WC observers.
In order to directly test the hypothesis of a differential
use of extrafoveal information across cultures during face
recognition, we used the Blindspot technique in an oldnew task with EA and WC participants and with paramet-
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Blindspots abolish cultural fixation bias for faces
Link Manual) and using Matlab software. Calibrations
were then validated with the EyeLink software and repeated when necessary until the optimal calibration criterion was reached. At the beginning of each trial, participants were instructed to fixate a series of crosses centered
in the 4 quadrants of the screen in order to validate the
calibration. Then, they had to fixate a cross at the centre
of the screen to perform a drift correction. If the drift
correction was more than 0.5°, a new calibration was
launched to insure an optimal tracking accuracy. The
eyetracker, software and setting used in Glasgow and Sun
Yat-Sen universities were identical. The Blindspot was
either absent (Natural-vision), 2°, 5° or 8° degrees of
visual angle, and moved contingent to the participant’s
gaze position. The display contingent to gaze position
updating required 11ms on average (between 8 and
14ms), eliminating any impression of flickering for the
observers.
Method
Participants.
Fifteen Western Caucasian participants from the University of Glasgow, UK (5 males, mean age 25.9 years)
and fifteen East Asian participants from the Sun Yat-Sen
University, Guangzhou, China (7 males, mean age 24.8
years) participated in this study. All participants had
normal or corrected vision and were paid £6 or equivalent
per hour for their participation. All participants gave written informed consent and the protocol was approved by
the local ethical committees.
Stimuli.
Stimuli were obtained from the KDEF (Lundqvist,
Flykt & Öhman, 1998) and AFID (Bang, Kim & Choi,
2001) databases and consisted of 56 East Asian and 56
Western Caucasian identities containing equal numbers
of males and females. The images were 382x390 pixels in
size, subtending 15.6° degrees of visual angle vertically
and 15.3° degrees of visual angle horizontally, which
represents the size of a real face (approximately 19 cm in
height). Faces from the original databases were aligned
by the authors on the eye and mouth positions; the images
were rescaled to align those facial features position and
normalized for luminance. Images were viewed at a distance of 70 cm, reflecting a natural distance during human interaction (Hall, 1966). All images were cropped
around the face to remove clothing and were devoid of
distinctive features (scarf, jewellery, facial hair etc.).
Faces were presented on a 800x600 pixel grey background displayed on a Dell P1130 19” CRT monitor with
a refresh rate of 170 Hz.
Procedure.
The observers of both groups were exposed to the
four Blindspot conditions (Natural-vision, 2°, 5° or 8°
degrees of visual angle) in a random order. To ensure that
observers would deploy a reliable strategy with the gaze
contingent technique, the Blindspot conditions were
blocked. Participants started the experiment with a training session in order to familiarize them with the four
Blindspot sizes. Then, they were informed that they
would be presented with a series of faces to learn and
subsequently recognize. They were also informed that
they would be given four face recognition blocks containing Asian and Caucasian face stimuli (same number of
male and female faces in each block) and corresponding
to the four Blindspot sizes. In each block (one block for
each Blindspot size), observers were instructed to learn 7
face identities randomly displaying either neutral, happy
or disgust expressions. After a 30 second pause, a series
of 14 faces (7 faces from the learning phase – 7 new faces) were presented and observers were instructed to indicate as quickly and as accurately as possible whether
each face was familiar or not by pressing keys on the
keyboard with the index of their left and right hand. Response times and accuracy were collected and analyzed
for the purpose of the present experiment. Response buttons were counterbalanced across participants. The emotional expression of the faces was changed between the
learning and the recognition stage to avoid trivial image
matching strategies.
Eye-tracking.
Eye movements were recorded at a sampling rate of
1000 Hz with the SR Research Desktop-Mount EyeLink
2K eyetracker (with a chin/forehead rest), which has an
average gaze position error of about 0.25°, a spatial resolution of 0.01° and a linear output over the range of the
monitor used. Only the dominant eye of each participant
was tracked although viewing was binocular. The experiment was implemented in Matlab (R2007a), using the
Psychophysics (PTB-3) and EyeLink Toolbox extensions
(Brainard, 1997; Cornelissen, Peters, & Palmer, 2002).
Calibrations of eye fixations were conducted at the beginning of the experiment using a nine-point fixation
procedure as implemented in the EyeLink API (see Eye-
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Blindspots abolish cultural fixation bias for faces
Each trial started with the presentation of a central
fixation cross. Then four crosses were presented, one in
the middle of each of the four quadrants of the computer
screen. These crosses allowed the experimenter to check
that the calibration was still accurate. In this way, we
validated the calibration between each trial. A final central fixation cross served as a drift correction, followed by
a face presentation. Faces were presented for 5 seconds in
the learning phase and until the observer’s response in the
recognition phase. To prevent anticipatory strategies,
images were presented at random locations on the computer screen. Each trial was subsequently followed by the
6 fixation crosses which preceded the next face stimulus.
Results
Behavioral performance.
2 (Culture of Observer: Western or Eastern) x 4
(Blindspot size: Natural-vision, 2, 5, 8 degrees) ANOVAs
revealed a decrease of face recognition accuracy (F(3,
84)=4.32, p<0.01) and a trend to slower response times
(F(3, 84)=2.71, p<0.06) as the Blindspot size increased
(Figure 1). Western Caucasian and East Asian observers
were equally accurate and fast at recognizing faces (Fs (1,
28) < 1). The interaction between the Culture of the observer and the Blindspot size factors, for accuracy (F(3,
84)=.33, p=.80) and response times (F(3, 84)=1.93,
p=.13), failed to reach significance.
Data analyses.
The behavioural performance was measured by the
percentages of correct recognition and the reaction time.
For the eye-movement analysis, only correct trials were
analyzed. Trials further than 2 standard-deviations from
the average duration were discarded. Saccades and fixations were determined using a custom algorithm using the
same filter parameters as the EyeLink software (saccade
velocity threshold = 30°/sec; saccade acceleration threshold = 4000°/sec2) and merging fixations close spatially
and temporally (<20ms, <0.3°). Fixation distribution
maps were extracted individually for WC and EA observers. Previous studies did not reveal any impact of the task
(learning vs. recognition) or the stimulus face race (WC
vs. EA) on the statistical fixation maps (Blais et al., 2008;
Caldara et al., 2010; Kelly et al., 2010). Here, we analysed the recognition trials and collapsed data for the EA
and WC stimuli and face race. We computed the total
number of fixations to insure that EA and WC information sampling strategies are comparable. The statistical
fixation maps were computed with the iMap toolbox
(Caldara & Miellet, 2011). iMap establishes significance
using a robust statistical approach correcting for multiple
comparisons in the fixation map space, by applying a
one-tailed Pixel test (Chauvin, Worsley, Schyns, Arguin
& Gosselin, 2005; Zcrit > 4.07; p < .05) for the group
fixation maps and a two-tailed Pixel test (Zcrit |4.25|; p <
.05) on the differential fixation maps. Finally, for each
condition we extracted the average Z-score values for
each observer individually, within the regions showing
significance in the differential fixation maps for the Natural-vision condition. Cohen’s d effect sizes (Cohen, 1988)
of culture were calculated on the average Z-scores for
each region showing significance.
Figure 1.
Average percentage of correct response and reaction time (sec.)
for each culture of the observer and Blindspot size.
Eye-tracking measures.
A 2 (Culture of Observer: British or Chinese) x 4
(Blindspot size: No Blindspot, 2, 5, 8 degrees) ANOVA
conducted on the number of fixations (Table 1) did not
reveal any significant main effects of Culture of observers (F(1, 28) = 1.09, p>.3), Blindspot size (F(3, 84) =
0.53, p>.6), or interaction between Culture of observers
and Blindspot size (F(3, 84) = 2.04, p>.11).
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Miellet, S., He, L., Zhou, X., Lao, J. & Caldara, R. (2012)
Blindspots abolish cultural fixation bias for faces
Figure 2.
Fixation maps for each culture of the observer and Blindspot
size. The white contours visualize areas with above chance
fixation durations or differences.
Table 1.
Average number of fixations during recognition trials for each
culture of the observer and Blindspot size.
WC
observers
EA
observers
Natural
vision
2°
5°
8°
Blindspot
Blindspot
Blindspot
4.98
4.39
5.08
5.31
5
4.75
4.73
4.33
Figure 2 shows fixation maps and the regions significantly fixated above chance level according to iMap
(white contours) for EA and WC observers and for Natural-vision, 2°, 5° and 8° Blindspot during face recognition. The difference maps reveal the well-established
central bias for Easterners (in blue in the difference map)
and eye-mouth bias for Westerners (in red in the difference map) in the Natural-vision condition. These cultural
fixation biases progressively disappear for larger Blindspots, and in the 8° Blindspot condition, there is no consistent difference between the fixation patterns for WC
and EA observers. Crucially, the contrast between the
most extreme Blindspot conditions (Natural-vision versus
8°) revealed that Westerners dramatically changed their
fixation pattern while Easterners adopted a much more
constant exploration strategy (see last row in Figure 2).
Easterners keep looking in the middle of the face for Natural-vision or any Blindspot
size while the preferred eyes-mouth fixation locations for
Westerners in Natural-vision migrate toward the center of
the face with increasing Blindspot size.
These statistical analysis revealed significant interactions for those factors in the Natural-vision and 2° conditions (F(1, 28) = 10.61, p<.003 and F(1, 28) = 5.45, p<.03
respectively). WC observers spent significantly longer
fixating the eye region than EA observers in the Naturalvision and 2° conditions as revealed by independent twotailed t-tests (t(28) = 3.25, p<.005 and t(28) = 3.37, p<.03
respectively). In contrast, EA observers fixated longer on
the center of the face than WC observers in the Naturalvision condition (t(28) = 2.40, p<.03 ; only a trend was
observed in the 2° condition t(28) = 1.78, p=.08). Cultural
fixation biases on facial features were reliable and robust,
as highlighted by the large magnitude of Cohen’s d effect
size values for the significant effects (see Figure 3).
In order to determine the magnitude of the fixation biases across cultures, we extracted, for each observer, the
average of the Z-scored fixation durations within the areas showing significant differences in the differential fixation maps for Natural-vision (Figure 3). Then we carried
out, for each of the 4 Blindspot conditions, a two-way
mixed design ANOVA on the averaged Z-score values
with Face regions (a posteriori determined from the significant differences in the Natural-vision condition, eyes
versus centre) as a within-subject factor and Culture of
the observer as a between-subjects factor.
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Blindspots abolish cultural fixation bias for faces
fixations towards the centre of the face, abolishing cultural fixation biases observed in natural vision.
Figure 3.
Z-scored fixation durations within the Eyes and Nose areas (showing significant differences in Natural-vision,
**:p<.005,*:p<.05 ) for EA and WC observers, and for the four Blindspot conditions.
Discussion
In this study we employed the Blindspot gazecontingent technique to unequivocally establish a cultural
bias in extrafoveal information use for face recognition.
Face recognition performance (accuracy and reaction
time) was comparable for both groups of observers and
both groups performance deteriorated equally with the
Blindspot size increase. Our main prediction was thus
confirmed. The cultural fixation bias for face recognition
was replicated in the Natural-vision condition. This condition confirmed that WC observers display a triangular
fixation pattern sampling the eyes and mouth during face
identification (e.g., Althoff & Cohen, 1999; Groner et al.,
1984; Henderson et al., 2005), while EA observers favour
fixating the centre of the face as reported in many previous eye movement studies (Blais et al., 2008; Kelly et al.,
2010; Kita et al., 2010; Rodger et al., 2010). Crucially,
Westerners and Easterners showed similar eye movement
scanpaths in the large Blindspot condition, with extended
Figure 4 summarizes the results obtained in the present experiment and those of previous studies. The upper
panel illustrates the cultural fixation biases robustly observed for WC and EA participants during face recognition. The lower panel shows how masking extrafoveal
information leads to an Western-like fixation pattern for
EA observers (Caldara et al., 2010 with the Spotlight
technique) while masking foveal information leads to an
Eastern-like fixation pattern for WC observers (present
study with the Blindspot technique); both manipulations
eliminating differences between the cultural groups fixation pattern. Altogether these results suggest that, in natural vision, Easterners rely more on extrafoveal information sampling during face processing than Westerners;
although both groups of observers use the same facial
features for face recognition.
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Blindspots abolish cultural fixation bias for faces
Figure 4.
Upper panel: Fixation maps showing the fixation biases for WC and EA participants during face recognition in previous
studies and present experiment. White contours indicate significant areas according to iMap (Caldara & Miellet, in
press) Lower panel: Spotlight (Caldara et al., 2010) and Blindspot’s (present study) results revealing the abolition of
differences between the cultural group’s fixation pattern when masking extrafoveal and foveal information respectively.
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Blindspots abolish cultural fixation bias for faces
Although WC and EA observers show culture-specific
information sampling strategies during face recognition,
observers of both group are able, under particular constraints (gaze-contingent masking of face information), to
use the “opposite” strategy, the one of the other cultural
group. Crucially, this strategy shift in response to the
viewing conditions is not paired by any loss of performance. Spotlight and Blindspot have the same effect on
performance for both groups of observers. This indicate
that although WC and EA observers use preferentially
distinctive information sampling strategies in face recognition (foveal versus extrafoveal), they do not necessarily
extract information more efficiently in their favourite
strategy.
viewing conditions such as lighting, distance, first fixation location on the face, occlusions (hair, shade, hat),…
It is still unknown how preferential information sampling
strategies during face recognition would emerge in a given culture and further studies are necessary to elucidate
this point. However, human beings are extremely efficient at assessing others’ gaze direction and they can do it
as young as 10 weeks old (Hood, Willen, & Driver,
1998). Thus, alignment and social imitation (see Garrod
& Pickering, 2009 for discussion of multilevel alignment)
might be sufficient to explain the emergence of such cultural biases in information sampling strategies for face
recognition. Importantly, regardless of these theoretical
considerations, the present data (together with Caldara et
al., 2010 and Miellet et al., 2011) demonstrate that, although different cultural groups adopt preferentially specific visuo-motor strategies for face recognition, individuals can flexibly adapt their information sampling strategies depending on the visual constraints.
Miellet, Caldara & Schyns (2011) recently introduced
the iHybrid technique in order to examine whether local
or global information subtends face identification. In this
technique, two identities are combined in a gazecontingent paradigm using a retinal filter, based on spatial frequency bands decomposition, in order to eliminate
any perception of the composite aspect of the stimuli.
Hence, iHybrids simultaneously provide local, foveated
information from one face and global, extrafoveal information from a second face. Behavioral face identification
performance and eye-tracking data show that the visual
system can identify faces on the basis of foveally and
extrafoveally sampled information. All observers used
both strategies, often to recover the very same identity. In
short, the consistent cultural bias on fixation patterns during face recognition would reflect a shift between the
distributions of foveal versus extrafoveal information
sampling strategies for WC versus EA participants. However, it is important to keep in mind that these strategies
are not mandatory. In fact, their use seems extremely
flexible. The same observer might use one or the other
(local/foveal versus global/extrafoveal) on different trials
depending on the first fixation location on the face (Miellet et al., 2011). Moreover, EA observers can shift from
their favourite strategy (central bias) to the WC observers’ favourite strategy (eyes-mouth bias) without any cost
in terms of performance (Caldara et al., 2010 using the
Spotlight technique).
Acknowledgments
This study was supported by the Swiss National Science Foundation (100014_138627).
In the same way, there is no cost for WC observers to
adopt the EA observers’ favorite strategy (present study
with the Blindspot technique). The flexibility in information sampling strategy is obviously highly adaptive
and enables face recognition despite variations in the
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Journal of Eye Movement Research
5(2):5, 1-12
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variation in eye movements during scene perception.
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