A novel on-demand remote testing system for infant visual perception1 - J-Stage
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The Japanese Journal of Psychonomic Science
2022, Vol. 40, No. 2, 1–11
全員分の苗字・苗字・苗字： Original Article1
ランニングタイトル●●●●●●●●●●●●●●●
DOI: http://doi.org/10.14947/psychono.40.27
A novel on-demand remote testing system for infant visual perception1
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a, a b c
Nobu Shirai *, Mizuki Kawai , Tomoko Imura and Yumiko Otsuka
a
Niigata University
b
Japan Womenʼs University
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c
Ehime University
Although recent advances in the tools and platforms used for remote psychological experiments have allowed
experimental psychologists to safely continue their research during the COVID-19 pandemic, procedures for remote
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studies of infant vision are not established. Here, we report a newly developed procedure for on-demand remote ex-
periments on infant vision. We provided participants (parents of infants) with a portable apparatus (a computer tab-
let) and instructions for conducting the experiments in their homes. A custom application controlled the stimulus
presentation and video recording of infant behavior via the tablet s front-facing camera. Videos of the infants look-
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ing behaviors saved on the tablet were analyzed off-line by the experimenters. Using this method, we tested 24 in-
fants aged 6–12 months and successfully replicated the findings of previous lab-based studies on optic flow percep-
tion in infancy. The newly developed method holds promise for use in remote studies of infant vision.
Ke y words : infant vision, on-demand remote experiment, preferential looking technique
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remote research may not allow all populations to be studied.
Introduction
For example, conducting remote research on visual develop-
The coronavirus disease 2019 (COVID-19) pandemic has ment in young infants is challenging. Infant vision is typically
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made it difficult to safely conduct psychological experiments evaluated based on looking times to visual stimuli (e.g., the
using conventional methods, which require the presence of preferential looking technique: cf. Fantz, 1961, 1963). Such a
participants in the laboratory. Many experimental psycholo- method requires the live coding or offline coding of the look-
gists have thus been obliged to conduct remote experiments to ing behavior of infants during the experiment. In the case of
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continue their research. Several tools and platforms were re- offline coding, naïve observers analyze video recordings of in-
cently designed for remote experiments (e.g., Cauldron, 2021; fants looking behaviors to determine whether they signifi-
de Leeuw, 2015; Henninger, Shevchenko, Mertens, Kieslich, & cantly discriminated between visual stimuli. However, the
Hilbig, 2020; Peirce et al., 2019), and these tools have contrib- tools and platforms commonly used for remote experiments
uted to the continued data collection in experimental psychol- have limited ability to obtain high-quality video recordings of
ogy research during the COVID-19 pandemic. infants looking behaviors, and to the best of our knowledge,
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Nonetheless, the currently available systems and tools for most of them cannot automatically record the behavior of par-
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ticipants during the experiments. In addition, the camera po-
* Correspondence should be sent to: Nobu Shirai, Depart-
sition varies among the many personal devices that are used
ment of Psychology, Faculty of Humanities, Niigata
University, 2–8050 Ikarashi Nishi-Ku Niigata, 950–2181, for running such experiments, and some devices do not even
Japan. E-mail: nobu.shirai@gmail.com have a camera. This makes it very difficult to obtain ideal vid-
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1
This study was financially supported by Grants-in-Aid for eo recordings of infants looking behaviors when using the ex-
Scientific Research from the Japan Society for the Promo-
isting remote experiment techniques. Moreover, use of the
tion of Science (nos. 19H00631, 19H01119, and 20K20678
to NS and no. 18H03506 to TI) and a Grant-in-Aid for Sci- participants own equipment results in visual stimuli with in-
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entific Research on Innovative Areas [17H06344] Con- consistent physical properties (e.g., size, resolution, and re-
struction of the Face-Body Studies in Transcultural Condi- fresh rate). Although this inconsistency may have little effect
tions from MEXT, Japan to YO. We thank Dr. Harold Hill
on studies with adults, who have mature visual systems (e.g.,
for his helpful comments on an earlier version of our man-
uscript. We also thank Akiho Ono and Nahoko Sato for previous research confirmed that the use of various portable
their assistance with data collection. devices provides valid results for adult studies: Burke et al.,
J-STAGE First published online: April 15, 2022
Copyright 2022. The Japanese Psychonomic Society. All rights reserved.2 The Japanese Journal of Psychonomic Science Vol. 40, No. 2
2017; Germine et al., 2012; Schatz, Ybarra, & Leitner, 2015), parcel delivery service and instructed the parents regarding
such inconsistency could significantly affect estimates of the how to run the application. After the experiment, the parents
visual abilities of young infants, who have lower visual acuity sent back the tablets, and the video recordings of their infants
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and contrast sensitivity compared to adults (Atkinson, 2000). looking behaviors were extracted. This new technique allows
The qualities of visual stimuli must therefore be standardized remote experiments to be conducted using a standardized
in studies of infants. methodology, and visual stimuli can be controlled to a greater
A pioneering work by Semmelmann, Hönekopp, and Wei- degree compared to the existing systems.
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gelt (2017) tackled the difficulty in conducting remote experi- We conducted the present study to validate this newly de-
ments for infant vision research. They attempted to conduct a veloped on-demand remote experiment technique by replicat-
preferential looking experiment by using a web-based online ing previous lab-based studies that examined the optic flow
application. The families participated in the experiment by us- perception in infancy (Shirai & Imura, 2014; Shirai, Kanazawa,
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ing their own personal computers (PCs), and the looking be- & Yamaguchi, 2008). Those studies revealed a robust looking-
haviors of infants during the experiment were recorded preference for radial optic flow patterns across a wide age
through the participants PC s web camera. While Semmel- range in infancy: radial expansion (or contraction) and unidi-
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mann et al. (2017) stated that their method could obtain infant rectional laminar (upward, downward, leftward, or rightward)
gaze responses with acceptable quality, they also reported that flow patterns were displayed, and the infants looking prefer-
the quality of the obtained movies was highly dependent on ence for a radial flow compared to a laminar flow was exam-
the computer environment of the participants. For example, ined. Shirai et al. (2008) tested younger infants (aged 2–3
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the frame rate of the recorded movies had a wide variation months) by the preferential looking method, whereas Shirai &
(from 3 to 30 frames/s). Thus, although the study by Semmel- Imura (2014) tested infants aged 5–12 months by the forced-
mann et al. (2017) is a pathfinding work for remote experi- choice preferential looking method. Despite these differences
ments in infant vision research, their results highlight the in methods and subjects, the two studies both found that
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challenges of testing infant vision in a remote manner. young infants have a strong preference for radial flow (espe-
Here, we devised a new technique to remotely evaluate in- cially expansion flow) patterns compared to non-radial flow
fant vision. A computer tablet is the main component of the patterns (such as a laminar flow). That is, both studies consis-
apparatus for our remote experiment technique. Using a tablet tently reported that infants exhibited a greater visual prefer-
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or similar portable device has become a very common method ence for radial expansion (or contraction) compared to the
for conducting psychological experiments (Lamond et al., laminar flow pattern, and the preference was more pro-
2008; Thorne et al., 2005), including developmental research nounced for the expansion compared to the contraction flow
(e.g., Dobson et al., 2004; Frank, Sugarman, Horowitz, Lewis, patterns.
& Yurovsky, 2016). It was demonstrated that acceptable results Given the robustness of the radial flow preference during
can be obtained in a tablet-based preferential looking experi- infancy, we speculated that the radial flow preference could be
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ment for 3- to 9-year-old children (although it was a lab-based a good benchmark to estimate the validity of our newly devel-
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project; Dubey et al., 2019). We thus speculated that a tablet oped remote experimental procedure, and that we would ob-
could be used to establish a remote preferential looking exper- tain results comparable to those of the above-cited lab-based
iment even for young infants, and we developed an application studies if our new remote procedure is valid for testing infant
to run a remote infant vision experiment using a commonly vision.
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available tablet. This application controls the presentation of a
Methods
visual stimulus to an infant and automatically records the in-
fant s looking behaviors via the built-in front camera of the Ethics statement
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tablet. This study was approved by the Ethics Committee for
The present experiment was conducted in an on-demand Human Research of Niigata University, Japan. All experi-
manner: parents and infants could complete the experiments ments were conducted in accordance with the Declaration of
in their homes at a time convenient to them. We dispatched Helsinki.
the tablets to the homes of the participating infants by using aShirai et al.: A novel on-demand remote testing system for infant visual perception 3
Participants experiment; see the Procedures section for details), the sample
Participants were recruited via flyers distributed at public size had to be a multiple of 8. We therefore set the sample size
health centers in Niigata City, Japan, and a flyer on the website as 24 (＞20 and a multiple of 8).
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of our research lab. Families who voluntarily responded to the
announcements were included in the experiments. The final Apparatus
analysis included data from 24 full-term infants (weight A tablet (iPad 7th gen, 32 GB; Apple Inc., Los Altos, CA,
≥2,500 g at birth; 11 girls; mean and standard deviation [SD] USA) was used to display visual stimuli and record videos of
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age＝322.9 ± 45.7 days; range: 174–374 days; i.e., roughly 6- the infants looking behaviors. A custom application written
to 12-month-olds). Seven other infants participated in the ex- using the Swift language (XCode, ver. 12.0; Apple Inc.) con-
periments but were excluded from the analysis because of in- trolled the presentation of stimuli and the recording of the in-
complete participation (N＝5), indistinct recordings of the fants looking behaviors, via the built-in front camera of the
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infant s gaze because the viewing distance was too long (N＝ tablet. The tablet was positioned in front of the participants in
1), or indistinct recordings of the infant s gaze because of in- portrait orientation using a tablet stand (100-LATAB013W;
correct placement of the wide-angle conversion lens attached Sanwa Supply, Okayama, Japan) (Figure 1a). A wide-angle
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to the tablet (N＝1). The parents of each infant provided writ- conversion lens (P-SL04BK; Elecom Co., Osaka, Japan) was at-
ten informed consent prior to the experiments and confirmed tached to the front camera of the tablet to allow the entire face
that the infant had no known visual deficits. of each infant to be recorded, even during movements.
We determined the sample size (N＝24) based on the fol-
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lowing. As mentioned in the Introduction, the aim of the pres-
ent remote experiment was to replicate the findings of the lab- 2
The individual data of the preference scores for expansion
based studies by Shirai et al. (2008) and Shirai and Imura and contraction flows under the speed condition of 3.2
(2014). While these two studies targeted infants of different deg/s (the speed condition that is most similar to the
present condition) from the original dataset of Experiment
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ages and used different methods to measure the preferences of
1 in Shirai and Imura (2014) (a total of 106 infants aged 5-
infants, they obtained the same two main findings: (a) infants to 12-months) were extracted and used for the calculation.
had a stronger preference for radial flows (expansion flows in The mean preference scores (and ±1 standard deviation
particular) than laminar flows, and (b) the preferences for ra- [SD]) for the expansion and contraction flows were 0.735
(±0.136) and 0.596 (±0.157), respectively. Using the
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dial flows were significantly larger for radial expansion flows
mean preference scores and SDs, we calculated the effect
compared to radial contraction flows. Thus, our main con- sizes (Cohen's d) of the difference between the preference
cerns were whether the two above-described findings would score for expansion flow and chance (0.5), the difference
be replicated. To calculate the sample size for the present between the preference for contraction flow and chance,
and the difference between the preferences for expansion
study, we used the individual data (distributed via http://
and contraction flows.
dx.doi.org/10.6084/m9.figshare.808626) reported by Shirai
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The results revealed the effect sizes (d) of 1.73, 0.61, and
and Imura (2014), who tested infants in a similar age range. 0.95, respectively. We used these effect sizes to estimate the
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Our calculations suggested that a suitable sample size would sample size required for the statistical test for each of the
following comparisons: expansion preference vs. chance
be 11 infants (details of the calculation are described in a foot-
level (two-tailed one sample t-test), contraction preference
note2). However, we considered that this estimate might not be vs. chance level (two-tailed one sample t-test), and expan-
applicable in light of the differences in experimental settings sion preference vs. contraction preference (two-tailed
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between the Shirai and Imura (2014) study and our present in- paired t-test). The estimated sample sizes that we obtained
by using G power 3.1 (Faul, Erdfelder, Buchner, & Lang,
vestigation. In addition, a sample size of ＞20 per experimen-
2009) and by setting the statistical power of each test as 0.8
tal group has been recommended for conducting psychologi- were 5, 24, and 11, respectively. Given the main findings
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cal research (Simmons et al., 2011). Finally, because we needed that we were validating, it was apparent that the most im-
to fully counterbalance the total of eight combinations of ex- portant comparisons in the present study would be those
between the expansion preference and the chance level
perimental settings across participants (i.e., 2 orders of two ex-
and between preferences for expansion and contraction
periments × 2 positions of optic flow patterns in the first ex- flows. Thus, the required sample size could be estimated as
periment × 2 positions of optic flow patterns in the second 11.4 The Japanese Journal of Psychonomic Science Vol. 40, No. 2
in front of the apparatus while gently holding their infant in
their lap. The parents were asked to measure the distance be-
tween the tablet and the infant s face by themselves and to
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keep the viewing distance at 20 cm (Figure 1b) (note that the
Swift application has no specific function to automatically
check the viewing distance).
Once the application was launched, a calibration panel ap-
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peared on the screen (Figure 2); the panel consisted of a small
window showing the video input. The parents could use this
Figure 1. (a) The tablet and tablet holder, and (b) the panel to adjust the relative position of their infant to the tablet,
arrangement of the apparatus and the postures of the
so that the infant s face was positioned near the center of the
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infant and parent during the experiments.
window; this ensured that a good view of the infant s face
would be obtained during recording. After the infant s head
Stimuli was properly positioned, the parent touched the Start but-
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Each visual stimulus consisted of two optic flow patterns ton on the lower area of the calibration panel, which initiated
placed side by side on a white background. Each stimulus was the experiment and video recording. The parents were in-
presented as an animation in MP4 format (30 frames/s). structed not to look at the tablet screen during the experi-
Although the original resolution of the animation was ment, either by looking in a different direction or simply clos-
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1,920 × 1,080 pixels (px), it was rescaled to the native resolu- ing their eyes.
tion of the tablet (1,620 × 911 px) when the animation ap- Each experiment consisted of two consecutive trials, and
peared on the tablet screen. All stimuli were presented in the each trial was comprised of two phases. At the beginning of
upper half of the screen (Figure 1a) so that the infant s eyes re- each trial, an attention grabber (a cartoon character emitting
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mained fixated just below the tablet camera. Each flow pattern beeping sounds; width, 6.9°; height, 9.2°) appeared at the cen-
(diameter＝16.4°) was composed of 100 moving black dots ter of the presentation field for 5 s, followed by a visual stimu-
(diameter＝0.3°). lus for 10 s. The position of the flows alternated between the
Each stimulus comprised two flow patterns: a radial flow two trials; for example, a radial (or laminar) flow appeared on
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(either expansion or contraction) and a unidirectional laminar the right (or left) side in the first trial and on the left (or right)
flow (upward, downward, leftward, or rightward). The dis- side in the second trial. The initial position of each flow was
tance between the centers of the flow patterns was 32.8°. Dots counterbalanced across participants. No manipulation of the
were deleted at the end of their lifetime (5 frames) or when the apparatus by the parents was required during the experiment,
edge of the flow area was reached, and they were then re-plot- and the two trials were conducted in sequence automatically
ted at a random point in the flow field. All dots moved at a after the experiment had been initiated.
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constant speed of 2.5°/s, which was determined in accord with Following the second trial, an audible message ( This ex-
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the results of Shirai and Imura (2014), who reported that 5- to periment has been completed. Thank you for your coopera-
12-month-olds (similar to the age of the present participants) tion in Japanese) was played to inform the participants that
exhibited a strong preference for radial compared to laminar the experiment had concluded, and the application was shut
flow patterns at a similar speed (range 1.6–3.2°/s). down. Recordings of the infants looking behaviors were auto-
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matically saved by the tablet.
Procedures Each participant engaged in two experiments: one with
The parents of the study participants were sent instruction stimuli composed of radial expansion and laminar flows (the
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leaflets, a consent form, and the apparatus (the tablet, the expansion condition), and another with stimuli composed of
wide-angle conversion lens, and the tablet holder) via a parcel radial contraction and laminar flows (the contraction condi-
delivery service. Parents were asked to place the apparatus on tion). Therefore, each participant participated in four trials in
a stable desk in a quiet room. No specific instructions were total (two trials each for the expansion and contraction condi-
provided regarding the light conditions. One of the parents sat tions). The order of the two experimental conditions wasShirai et al.: A novel on-demand remote testing system for infant visual perception 5
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Figure 2. Flowchart of the experiment. (a) A calibration panel appeared on the tablet screen when the parent initiated the ap-
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plication. The live view from the tablet s front camera was displayed in a small rectangular window in the upper half of the
calibration panel. (b) The parent monitored the rectangular window and adjusted their infant s postures and the position of
the apparatus accordingly. The parent clicked the START button to begin the experiment. (c) The first trial began with
the presentation of an attention grabber for 5 s, (d) followed by the first stimulus for 10 s. (e) After the first trial, the second
trial began automatically with the presentation of an attention grabber for 5 s, (f) followed by the second stimulus for 10 s.
(g) At the end of the second trial, an audio message notified the parent that the experiment had been completed, and the ap-
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plication shut down automatically.
counterbalanced across participants. The direction of the depending on whether the infants were looking at the right or
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laminar flow (upward, downward, leftward, or rightward) was left areas of the tablet screen. The key press was maintained
selected at random for each trial. Both experiments were for as long as the infant was looking at the screen, and this du-
conducted on the same day. The two experiments were ration was taken to indicate the looking time. No key was
implemented in separate applications: two independent appli- pressed if the infant was not looking at the screen. Another
cations were preinstalled on the tablet, and the parents were author (MK; the sub-coder) repeated the same coding method
asked to tap relevant icons in the instructed order to run the for all recordings to evaluate the validity of the coding by the
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experiments. main coder. A high correlation (r＝0.968) was observed be-
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After the experiments, the parents returned the signed con- tween the coding results (192 results: 4 trials × 2 areas × 24
sent form and the apparatus to the laboratory by using a parcel participants) of the main coder and sub-coder, which con-
delivery service via cash-on-delivery mode, and the shipping firmed the high inter-rater reliability of the coded data. The
cost was covered by the authors. values from the main coder were used in the statistical analy-
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sis.
Data coding Note that we expected that generally lower attention to the
One of the authors (NS; the main coder) coded the videos visual stimuli (shorter total looking times) would be possible
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of the infants looking behaviors by using a custom event re- in the present experiments compared to the previous lab-
corder developed using Processing software (ver. 3.5.4; The based study, because the present experiments were performed
Processing Foundation, New York City) and a PC. The coder in a household environment. We had thus planned to not ex-
was blind to the stimuli properties and position in each video. clude any participants based on looking duration, because we
The coder pressed assigned keys on the computer keyboard suspected that the use of a strict looking-time exclusion crite-6 The Japanese Journal of Psychonomic Science Vol. 40, No. 2
rion would result in a major loss of participants. However, we of the experimental trials suggests that, overall, our visual
found that the participants were generally well attentive to the stimuli well attracted the attention of the infants. Figure 3 de-
visual stimuli (see also Table 1). picts the mean preference scores for the expansion and con-
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Individual preference scores for the radial flow pattern were traction conditions. A two-tailed one sample t-test (chance
calculated separately for the expansion and contraction condi- level: 0.5) revealed significantly higher preference scores for
tions, based on the coded looking times (preference score＝ both the expansion and contraction conditions compared to
total time looking at radial flow/total times looking at radial chance (t[23]＝9.33, p＜.001, d＝1.90; t[23]＝5.64, p＜.001,
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and laminar flows). d＝1.15, respectively). The infants were thus able to discrimi-
nate between radial and laminar flows, and they preferred ra-
Results
dial flows, as Shirai et al. (2008) and Shirai and Imura (2014)
Main findings also observed.
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The individual looking-time data for each of the two exper- A two-tailed paired t-test showed significantly higher pref-
imental conditions are provided in Table 1. The relatively high erence scores for the expansion condition compared to the
ratio (＞80％) of the total looking time to the entire duration contraction condition (t[23]＝3.26, p＝.003, d＝0.75). There-
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Table 1.
Individual looking times of the infants during the experiments.
Expansion condition Contraction condition
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Total looking Total looking
Looking Looking ％ total Looking ％ total
No. time to Looking time to
time to time to looking time time to looking time
Participants radial and time to radial and
radial flow laminar flow to the whole laminar flow to the whole
laminar flow radial flow laminar flow
pattern pattern duration pattern duration
patterns pattern (ms) patterns
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(ms) (ms) of two trials (ms) of two trials
(ms) (ms)
1 12549 4717 17266 86.33 11302 7901 19203 96.015
2 7991 781 8772 43.86 10632 6870 17502 87.51
3 5795 6702 12497 62.485 10897 7666 18563 92.815
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4 15803 1234 17037 85.185 7066 5629 12695 63.475
5 16947 670 17617 88.085 16971 1067 18038 90.19
6 10324 6338 16662 83.31 13024 2221 15245 76.225
7 14767 1069 15836 79.18 10646 3081 13727 68.635
8 12956 4130 17086 85.43 10303 8201 18504 92.52
9 9914 7883 17797 88.985 14837 3918 18755 93.775
10 16214 2423 18637 93.185 13379 4750 18129 90.645
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11 10382 6493 16875 84.375 8589 7018 15607 78.035
12 16421 2284 18705 93.525 14736 3920 18656 93.28
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13 9680 3894 13574 67.87 11973 6451 18424 92.12
14 17468 1201 18669 93.345 12183 7630 19813 99.065
15 14583 3202 17785 88.925 17103 1403 18506 92.53
16 14070 3316 17386 86.93 9354 8241 17595 87.975
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17 9902 7900 17802 89.01 5234 11149 16383 81.915
18 11194 2430 13624 68.12 12021 4316 16337 81.685
19 16687 0 16687 83.435 13980 3967 17947 89.735
20 9300 4766 14066 70.33 8417 5865 14282 71.41
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21 13180 4467 17647 88.235 10948 3498 14446 72.23
22 9864 4462 14326 71.63 9985 8395 18380 91.9
23 12102 3605 15707 78.535 5132 3984 9116 45.58
24 14498 3099 17597 87.985 10696 6000 16696 83.48
Ave. 12608.0 3627.8 16235.7 81.2 11225.3 5547.5 16772.9 83.9
SD 3185.2 2274.6 2356.8 11.8 3111.8 2503.8 2496.6 12.5Shirai et al.: A novel on-demand remote testing system for infant visual perception 7
(or between) the experiments. However, such instructions
were not possible during the on-demand remote experiments
performed in this study, and our present findings may thus
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have been confounded by effects of the parents looking be-
haviors. We therefore conducted additional coding and analy-
ses to investigate the relationship between infant and parent
looking behaviors.
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The looking behaviors of the parents were coded using the
same procedure described above for the looking behaviors of
the infants, except that the parents behaviors were divided
into only two categories: looking at the screen or not looking
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at the screen. This is because the longer distance between the
camera and the parents prevented an analysis of whether the
parents were looking at the right or left side of the screen. The
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coders were simply asked to press the assigned key if a parent
Figure 3. Bars: the mean preference scores for radial looked at the screen. We excluded two parents from this analy-
flow under the expansion (gray bars) and contraction sis because their faces were temporarily out of view in the re-
(white bars) conditions for all participants (N＝24). corded videos. The coding results from the main coder and
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Error bars: ± 1 standard error of the mean (SEM).
sub-coder had a high correlation (r＝0.925; coding results＝
Spaghetti plot: the individual preference scores under
each condition. 88; 4 trials × 22 participants), which confirmed the high inter-
rater reliability of the coded data. We thus subjected the data
fore, the infants exhibited a greater preference for expansion coded by the main coder to further analysis.
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flows compared to contraction flows, which was also consis- Based on the parents looking behaviors, we divided the 22
tent with previous results (Shirai et al. 2008; Shirai & Imura, infants into two groups: infants with shorter-looking parents
2014). (N＝15; infant age＝316.9 ± 54.9 days; range: 174–374 days)
and those with longer-looking parents (N＝7; age＝
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Additional exploratory analyses 336.0 ± 25.4 days; range: 304–371 days). The parent who
When we started this study, we did not plan or expect to ob- looked at the tablet screen for more than 2 s during the four
tain recordings of the looking behaviors of parents. However, trials (5％ of the entire duration of visual stimuli presentation
because the camera s angle of view was wide enough to in- [40 s]) was classified as longer-looking parents. Table 2 sum-
clude the parents seated behind their infants, we were also able marizes the looking times of the parents. Figure 4 depicts the
to observe the parents behaviors. This unexpected recording mean preference scores in the expansion and contraction con-
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of the parents behaviors revealed that, despite being instruct- ditions for both groups.
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ed not to, some parents looked at the tablet screen during the We expected that the potential effect of the parents looking
experiments, which may have affected the infants looking be- behaviors on their infants would be minimal or negligible in
haviors in unexpected ways (e.g., infants may have copied the the group with shorter-looking parents. To determine whether
parents looking behaviors or the parents may unconsciously our main finding of the infants radial flow preference would
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have directed the infant s body toward one of the visual stimu- remain without the influence of their parents looking behav-
li). To prevent unexpected effects of the looking behaviors of ior, we conducted two-tailed one-sample t-tests (chance level:
parents on the looking behaviors of their infants during visual 0.5) on the preference score of the infant group with shorter-
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development experiments, the parents are usually instructed looking parents. The t-tests revealed significantly higher pref-
not to look at the visual stimuli. For laboratory-based in-per- erence scores for both the expansion and contraction condi-
son experiments, an experimenter typically monitors the in- tions compared to chance (t[14]＝7.47, p＜.001, d＝1.92;
fant and parent behaviors in real time. If necessary, an experi- t[14]＝4.13, p＝.001, d＝1.07, respectively). A two-tailed
menter can urge the parents not to look at the stimuli during paired t-test also showed significantly higher preference scores8 The Japanese Journal of Psychonomic Science Vol. 40, No. 2
Table 2.
Individual looking times of the parents during the experiments.
(a) the shorter-looking parent group (N＝15) (b) the longer-looking parent group (N＝7)
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％ total looking ％ total looking
No. Total looking time time to No. Total looking time time to
Participants of the parents (ms) the whole duration Participants of the parents (ms) the whole duration
of the trials of the trials
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2 133 0.33 3 36593 91.48
4 248 0.62 7 5382 13.46
5 0 0.00 13 27262 68.16
6 0 0.00 14 3086 7.72
8 0 0.00 16 32674 81.69
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9 0 0.00 21 15651 39.13
10 0 0.00 24 36132 90.33
11 0 0.00
12 0 0.00
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15 0 0.00
17 0 0.00
18 134 0.34
19 901 2.25
22 0 0.00
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23 832 2.08
Ave. 149.9 0.4 Ave. 22397.1 56.0
SD 300.5 0.8 SD 14302.7 35.8
Participants no. 1 and no. 20 were excluded from the additional analysis because their faces were temporarily out of view in the
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video recordings.
for the expansion compared to the contraction condition
(t[14]＝2.14, p＝.047, d＝0.63). These results are well consis-
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tent with the main results of this study and suggest that there
was no pronounced effect of the parents looking behaviors
during the experiments on the infants looking behaviors.
Discussion
We developed an on-demand remote experiment system
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suitable for use in studies of visual development in infancy. Al-
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though most existing systems for remote psychological experi-
ments rely on participants own devices for stimulus presenta-
tion, we used the same apparatus for all participants, which
enabled us to standardize the visual stimuli and recorded vid-
va
eo. The main objective of this study was to test the validity of
the newly developed system for use in remote studies of infant
Figure 4. Bars: the mean preference scores for the in- vision. To this end, we investigated whether the newly devel-
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fants according to their parents looking behavior. Er- oped system could replicate the findings of two lab-based
ror bars: ± 1 SEM. Spaghetti plots: the individual pref- studies (Shirai et al., 2008; Shirai & Imura, 2014). We found
erence scores under each condition. Filled circles and
that our results successfully replicated the two main findings
solid lines: the data of the infants with parents looking
time＝0 ms. Open circles and dashed lines: the data of of the previous studies. First, the infants showed a significantly
the infants with parents looking time ＞0 ms. greater preference for radial flow patterns compared to unidi-Shirai et al.: A novel on-demand remote testing system for infant visual perception 9
rectional laminar optic flow patterns. Second, the infants there are also some limitations. Many confounding factors that
preference scores were significantly higher for radial expan- are typically controlled during lab-based testing could not be
sion compared to contraction. Our present findings thus indi- controlled. For instance, it is essentially impossible to perfectly
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cate that the on-demand remote system is valid for use in control the physical environment (e.g., lighting, sound, and
studies of infant vision. parental behaviors) during the experiments. Such factors may
have influenced the results obtained using the remote system.
Potential limitations Nevertheless, despite such uncontrollable factors, our results
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The current remote experiment was conducted by the par- replicated the findings of lab-based studies (Shirai et al., 2008;
ents of infants at home, which is likely to be a noisier and less Shirai and Imura, 2014). Another confounding factor that is
controlled environment than a laboratory. Such an environ- difficult to control during remote experiments is the looking
ment may have contributed to the shorter looking times. Of behavior of parents. However, in our study, the parents look-
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the two lab-based studies that this study was based on, the ing behavior did not significantly influence the infants look-
data from the study by Shirai and Imura (2014) were not suit- ing behavior, which suggests that the remote system may be
able for comparison with our present data, as those authors relatively robust to such unavoidable noise. Nevertheless,
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used the forced-choice preferential looking method (defining additional investigations may be required to strengthen the
the visual preference of infants based on the rate of the first validity of the new remote experiment system. One idea is to
gaze direction in each trial). In contrast, we calculated the use the same apparatus as the current on-demand remote ex-
preference score in the same way that Shirai et al. (2008) did. perimental system in a laboratory setting. Such a study repli-
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In order to compare looking times between the studies, we ob- cation could reveal the degree to which the above-mentioned
tained the looking-time data from the Shirai et al. (2008) uncontrollable factors influenced the infant behaviors ob-
study. Because the duration of experimental trials per experi- served herein.
mental condition was different between the study by Shirai et Finally, we confirmed the validity of the remote experiment
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al. (30 s [5 s × 6 trials]) and the present study (20 s [10 s × 2 system by using only one set of stimuli, i.e., dynamic motion
trials]), we calculated the ratio of the mean total looking time patterns with relatively high visual saliency and attractiveness
to the entire duration of the experimental trials in each of the for infants. It is unclear whether this system would work
experimental conditions in each study. Because 3-month-old equally well with less salient and attractive visual stimuli, such
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but not 2-month-old infants showed a radial flow preference, as static figures. Another study limitation is that the partici-
we used the Shirai et al. (2008) data of the 3-month-olds (N＝ pants were older (aged 6–12 months) than in some earlier
12, mean and standard deviation [SD] age＝97.0 ± 10.5 days; studies. Future research should include infants with a greater
range: 80–109 days) for the present comparison. The ratios of age range (especially younger infants) to validate the utility of
the total looking time under the low-speed condition of Shirai this system for all infants.
et al. (2008), which was the most similar to the stimuli in our
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present study, were 78.7 ± 18.9％ under the expansion condi- Merits of using the current on-demand experimental system
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tion and 81.0 ± 15.7％ under the contraction condition. The Our new system can be used for on-demand experiments to
ratio of the total looking time under the two other higher- test infant vision remotely. The worldwide COVID-19 pan-
speed conditions ranged from 80.4 to 83.5％. The mean ratios demic has prompted researchers in developmental sciences to
of total looking time in the present study were in a range simi- launch several remote projects; for example, the use of a vid-
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lar to those reported by Shirai et al. (2008): 81.2 ± 11.8％ un- eo-calling system and online observations of children s behav-
der the expansion condition and 83.9 ± 12.5％ under the con- iors (e.g., Childrenhelpingscience.com, 2020; Su & Ceci,
traction condition. Thus, although the infants in our present 2021). The research field of visual development is no excep-
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investigation were much older, the visual stimuli in our remote tion. Nelson and Oakes (2021) reported that they succeeded in
experiment appear to have attracted their attention at a level measuring the visual preferences of 4- to 12-month-old infants
comparable to that in the conventional lab-based experiments. by using an online platform for recording infant gaze behav-
Although the new system that we have developed has con- iors. Online platforms specialized to measure infant gaze be-
siderable benefits for use in remote studies of infant vision, haviors (see also Semmelmann et al. 2017) will provide one10 The Japanese Journal of Psychonomic Science Vol. 40, No. 2
possible solution for testing infant vision remotely. https://gorilla.sc/ (July 20, 2021).
However, such online testing procedures seem to have sever- Childrenhelpingscience.com (2020). ChildrenHelpingScience.
com Fun For Families, Serious For Science, Retrieved from
al limitations for investigating the visual functions of young in-
https://childrenhelpingscience.com (Nov. 10, 2021).
on
fants. Because an online platform must rely on the participants de Leeuw, J. R. (2015). jsPsych: A JavaScript library for creat-
own devices (e.g., a PC with a web camera) to display visual ing behavioral experiments in a Web browser. Behavior Re-
stimuli, various parameters of visual stimuli such as size, speed search Methods, 47, 1–12.
Dobson, V., Miller, J. M., Harvey, E. M., Clifford, C. E.,
(in cases of moving stimuli), and the refresh rate of frames can-
Haynes, B. M., & Mohan, K. M. (2004). A compact comput-
ati
not be controlled. Such uncontrollability is an important disad- er-based stimulus display for use in preferential looking
vantage for investigating visual perception, and particularly for assessment of infant vision. Investigative Ophthalmology &
testing lower visual functions. Moreover, as reported by Sem- Visual Science, 45, 4310–4310.
Dubey, I., Brett, S., Ruta, L., Bishain, R., Chandran, S., . . .
melmann et al. (2017), the qualities of video recordings (e.g.,
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Chakrabarti, B. on behalf of the START Consortium (2019).
the frame rate, resolution, sharpness, and angle of view) of the Quantifying social preference in young children using two
participant s gaze responses will exhibit wide variation. Such tasks on a mobile platform. Retrieved from https://doi.
unstable recordings of the looking behaviors of participants org/10.31234/osf.io/3un5e (November 10, 2021).
Fantz, R. L. (1961). The origin of form perception. Scientific
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may reduce the accuracy of coded results. The on-demand sys-
American, 204, 66–72
tem we have developed overcomes the above-mentioned limi- Fantz, R. L. (1963). Pattern vision in newborn infants. Science,
tations by using the same apparatus for all participants. 140, 296–297.
The results of this study indicate that the on-demand re- Faul, F., Erdfelder, E., Buchner, A. & Lang, A.-G. (2009). Statis-
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tical power analyses using G*Power 3.1: Tests for correla-
mote experiment system is a promising tool for research on
tion and regression analyses. Behavior Research Methods, 41,
infant vision, especially under circumstances that do not per- 1149–1160.
mit lab-based experiments. This system may also be a useful Frank, M. C., Sugarman, E., Horowitz, A. C., Lewis, M. L., &
complement to standard laboratory-based experiments, even Yurovsky, D. (2016). Using tablets to collect data from
young children. Journal of Cognition and Development, 17,
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after the COVID-19 pandemic. The system may reduce the
1–17.
mental and physical burden on research participants and their Germine, L., Nakayama, K., Duchaine, B. C., Chabris, C. F.,
family members. Standard experiments require the parents Chatterjee, G., & Wilmer, J. B. (2012). Is the Web as good as
and infants to visit the laboratory and remain there for a cer- the lab? Comparable performance from Web and lab in
cognitive/perceptual experiments. Psychonomic Bulletin &
On
tain period of time, and parents are required to dedicate their
Review, 19, 847–857.
personal time for the study and take the necessary precautions Henninger, F., Shevchenko, Y., Mertens, U. K., Kieslich, P. J. &
while traveling with infants. The infants are sometimes not in Hilbig, B. E. (2021). lab.js: A free, open, online study build-
a good state for experiments (e.g., sleepy, fussy) when they ar- er. Behavior Research Methods, doi.org/10.3758/s13428-019-
01283-5.
rive at the laboratory. In contrast, the new system allows par-
Lamond, N., Jay, S. M., Dorrian, J., Ferguson, S. A., Roach, G.
ents and infants to participate in the experiments at their con-
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D., & Dawson, D. (2008). The sensitivity of a palm-based
venience, in their own homes. We believe that the convenience psychomotor vigilance task to severe sleep loss. Behavior
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of this system may lead to the inclusion of a more diverse Research Methods, 40, 347–352.
Nelson, C. M. & Oakes, L. M. (2021). May I grab your atten-
range of infant participants̶e.g., infants of families who can-
tion? : An investigation into infants visual preferences for
not travel or live in remote areas, or infants who are shy or handled objects using Lookit as an online platform for data
anxious around strangers. collection. Frontiers in Psychology, 10:3389, https://doi.org/
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10.3389/fpsyg.2021.733218.
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