Effect of Mahjong on children's intelligence quotient

Abstract

This study investigated the effect of Mahjong, which is a table game played by three or four players and involves intellectual activity, on the intelligence quotient (IQ) of children. The participants were children between the age of 6 and 15 years, and their IQ was assessed immediately after enrolling in children's Mahjong classes and 1 year after the enrollment using the Wechsler Intelligence Scale for Children Fourth Edition (WISC-IV). Twenty children were included in the analysis. Their mean age at the time of the initial evaluation was 9 years and 6 months. In addition, we conducted a 1-year post-examination. The change in the IQ of this group was compared to that of a historical control group with a similar age range and test–retest interval. The mean overall full-scale IQ of the 20 children during the initial and post-1-year examinations was 106.05 and 113.75, respectively, and showed a statistically significant increase (p < 0.01). Based on the subscale index, the verbal comprehension index (VCI) and processing speed index (PSI) scores both showed a statistically significant increase from 100.6 to 106.75 and from 108.05 to 119.05 (p < 0.01), respectively. The PSI of the children included in the analysis showed a statistically significant increase compared to the historical control group. This study suggests that children who participate in Mahjong classes during their childhood have increased PSI scores of WISC-IV.

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TYPE Original Research
PUBLISHED 26 September 2022
DOI 10.3389/fpsyg.2022.934453
OPEN ACCESS
EDITED BY
Huei-Tse Hou,
National Taiwan University of Science
and Technology, Taiwan
REVIEWED BY
Shu-ming Wang,
Chinese Culture University, Taiwan
Min-Chai Hsieh,
Tainan University of
Technology, Taiwan
*CORRESPONDENCE
Takefumi Higashijima
higashijima0122@gmail.com
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This article was submitted to
Educational Psychology,
a section of the journal
Frontiers in Psychology
RECEIVED 03 May 2022
ACCEPTED 10 August 2022
PUBLISHED 26 September 2022
CITATION
Higashijima T, Akimoto T and Sakata K
(2022) Eect of Mahjong on children’s
intelligence quotient.
Front. Psychol. 13:934453.
doi: 10.3389/fpsyg.2022.934453
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©2022 Higashijima, Akimoto and
Sakata. This is an open-access article
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not comply with these terms.
Eect of Mahjong on children’s
intelligence quotient
Takefumi Higashijima*, Taisuke Akimoto and Katsumi Sakata
Department of Neurosurgery, Yokohama City University Medical Center, Yokohama, Japan
This study investigated the eect of Mahjong, which is a table game played
by three or four players and involves intellectual activity, on the intelligence
quotient (IQ) of children. The participants were children between the age
of 6 and 15 years, and their IQ was assessed immediately after enrolling
in children’s Mahjong classes and 1 year after the enrollment using the
Wechsler Intelligence Scale for Children Fourth Edition (WISC-IV). Twenty
children were included in the analysis. Their mean age at the time of the
initial evaluation was 9 years and 6 months. In addition, we conducted a
1-year post-examination. The change in the IQ of this group was compared
to that of a historical control group with a similar age range and test–retest
interval. The mean overall full-scale IQ of the 20 children during the initial and
post-1-year examinations was 106.05 and 113.75, respectively, and showed a
statistically significant increase (p<0.01). Based on the subscale index, the
verbal comprehension index (VCI) and processing speed index (PSI) scores
both showed a statistically significant increase from 100.6 to 106.75 and from
108.05 to 119.05 (p<0.01), respectively. The PSI of the children included in the
analysis showed a statistically significant increase compared to the historical
control group. This study suggests that children who participate in Mahjong
classes during their childhood have increased PSI scores of WISC-IV.
KEYWORDS
Mahjong, intelligence quotient, brain function, children’s Mahjong class, Wechsler
Intelligence Scale for Children
Introduction
Heredity is considered to strongly influence intelligence quotient (IQ). The degree
to which genes are involved in an individual’s characteristics is indicated by the concept
of heritability, expressed as 1.0 when the entire effect can be explained by genes. The
heritability of intelligence is approximately 0.8 (Sauce and Matzel, 2018), stronger than
the heritability of cancer (0.1), mental disorders (0.4) (Athanasiadis et al., 2022), and
body mass index (BMI) (0.6) (Elks et al., 2012). The heritability of BMI is higher during
childhood, and the influence of environmental factors becomes stronger as the child
grows. In contrast, for IQ, the younger the age, the more the individual is influenced by
the environment (Fulker et al., 1988). In addition to environmental and genetic factors,
IQ is also affected by training (Sauce and Matzel, 2018).
There is no consensus on whether interpersonal table games are correlated with IQ.
For chess, the most studied table game regarding its relationship with brain function,
some studies have shown that game skill is correlated with processing speed and executive
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Higashijima et al. 10.3389/fpsyg.2022.934453
function (Burgoyne et al., 2016). Furthermore, the average IQ of
chess players was approximately 120, higher than the population
average. In addition, a weak correlation was found between
chess performance and IQ (Bilali´
c et al., 2007). However, Bilali´
c
et al. (2007) reported that the amount of practice was the factor
that affected chess skills the most, but not IQ. This finding
was consistent with the report by Campitelli and Gobet (2011).
However, the relationship between chess and IQ is unclear, and
most studies exploring this relationship were cross-sectional.
Hence, a causal relationship has not been clearly identified. In
comparison, video games have been the subject of many positive
studies, indicating that the effects of video games increased
intelligence and cognitive function (Stern et al., 2011;Baniqued
et al., 2013;Oei and Patterson, 2013). This is not because video
games have a stronger impact on intelligence and cognitive
function than table games, but rather because video games are
easy and quick, and anyone can play them, making intervention
studies easier. Moreover, it is difficult to grasp the rules of table
games, such as chess, and they require a certain amount of
effort and a minimum level of intelligence as a prerequisite. This
makes it difficult to conduct prospective studies; therefore, fewer
prospective studies have been conducted.
Mahjong, a table game played by three to four players, uses
136 tiles, four each of 34 types. Each player has 13 tiles and has
to take one tile from the remaining blocks in a counterclockwise
direction and discard one simultaneously. This process is
repeated for approximately 70 rounds to complete the hand
as quickly as possible. During this process, the blocks and the
opponents’ hands are not revealed, and the player must make
the most advantageous choice based on the information of
their own hand and the tiles discarded by the opponents. The
information processing is very complex. Artificial intelligence
with algorithms comparable to those of top-level players was not
developed until 20 years after Deep blue, which was the artificial
intelligence for playing chess created by IBM, defeated the chess
champion in 1997 (Campbell et al., 2002;Li et al., 2020). In
Mahjong, players are provided with the opportunity to draw new
tiles in a counterclockwise direction. However, the order may
not turn out as planned, based on the act of “calling,” which
allows the player to take the tiles discarded by the opponent. The
players not only have to figure out the best move but also have
to anticipate the opponent’s moves. However, the information
to do so is not disclosed, and one has to use the opponent’s
gestures and facial expressions as clues to guess their moves.
Such complexity makes the creation of algorithms for artificial
intelligence difficult.
Recently, the effects of playing Mahjong on health,
particularly on brain function, have been studied (Table 1).
Mahjong has been shown to prevent depression in older adults
(Tang et al., 2021), improve cognitive performance, such as
verbal memory in patients with mild dementia (Cheng et al.,
2006,2014;Qiu et al., 2019;Zhou et al., 2020;Ding et al., 2022),
and improve higher brain functions, such as increased executive
function (Zhang et al., 2020). Based on this improvement
in executive function, Zang et al. concluded that Mahjong
improved higher brain function by activating frontal lobe
functions, such as concentration and anticipation. Fujimori et al.
(2015) measured the oxygen consumption of the brain while
playing Mahjong and reported that the activity of the temporal
and parietal lobes of the dominant hemisphere centered on
the temporal and parietal lobes. Increased blood flow in
these areas has been associated with increased intelligence,
particularly language comprehension and processing speed
indices (Kazumata et al., 2019;Sandvik et al., 2020). These
findings suggest that continued participation in Mahjong may
have an effect on IQ.
The purpose of this study is to investigate the effects of
Mahjong on IQ. Most previous studies on table games and
IQ have been cross-sectional ones, making it difficult to infer
the causal relationship. In addition, most studies on Mahjong
have focused on older adults, and the effects on children are
unknown. Furthermore, the effects of environment and training
on IQ are likely to be more pronounced in children with lower
genetic susceptibility. Hence, we prospectively observed and
verified whether intelligence increased in children who began
learning Mahjong.
Materials and methods
Participants
The participants were 35 children, who were Mahjong
beginners, aged between 6 and 15 years, and were enrolled in
the Neuron Children’s Mahjong Class, Oimachi School, between
January 2020 and January 2021. Those who had experience
in playing Mahjong were excluded from this study. However,
those assigned to the beginners’ class who had not learned
the rules of Mahjong and could not progress by themselves
were included. IQ evaluations were conducted at the time of
enrollment in the Mahjong class and after 1 year. For acquiring
the participants’ background information, we also conducted
interviews about other after-school activities, playing video
games, having siblings, and having family members who play
Mahjong (Table 2).
Children’s mahjong class
The Children’s Mahjong Class was held two times a month
on the first and third Sundays at the Neuron Mahjong School
Oimachi in Tokyo. In the first few days, the instructor taught
the rules. Three or four children sat around a table and played
the game while the instructor provided guidance as needed
(Supplementary Figure 1). Mahjong is a four-player game, which
requires social skills; specifically, it is characterized by teaching
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TABLE 1 List of previous literature studies on Mahjong.
Author Year Purpose Subject Study design Conclusion
Cheng et al. 2006 Cognitive function Elderly people with
dimentia twice a week
(n=33) Four times a
week (n=29)
Randomized controlled
Mahjong training for 16 weeks
Improved cognitive
symptoms in both groups
Saito et al. 2006 Brain activity of
Mahjong expert
Mahjong expert (n=8)
Healthy volunteers
(n=12)
Cross-sectional playing while actually
touching the Mahjong tiles
may alter the cross-modal
response of the tactile and
visual cortices.
Fujimori et al. 2015 Brain activity Healthy men (n=14) Cross over trial Measured
oxygenated hemoglobin
concentration during
Mahjong
Wernicke’s area and visual
cortex were more activated
than control.
Cheng et al. 2014 Cognitive function Elderly people with
dementia (n=110)
Mahjong group (n=36) Mahjong gradually improved
global functioning and
relieved symptoms of
dementia.
Tai chi group (n=39)
Hand craft group (n=35)
Randomized controlled
Mahjong training for 12 weeks
Tsang et al. 2016 Eye-hand coordination Elderly people who
played Mahjong (n=21)
did not play Mahjong
(n=20)
Cross-sectional People who play Mahjong
have better eye-hand
coordination.
Qiu et al. 2019 Cognitive function Elderly healthy people
(n=4,839)
Prospective cohort For 16
years
Playing cards or Mahjong
were associated with a
decreased risk of cognitive
impairment.
Zhou et al. 2020 Cognitive function Adult people (Age ≥45,
n=7,973)
Fixed effect analysis Playing Mahjong and using
the internet were associated
with improved memory
Zang et al. 2020 Cognitive function Elderly people with MCI
(n=28) control group
(n=28)
Randomized controlled
Mahjong training for 12 weeks
Playing Mahjong improved
the executive function
Tang et al. 2021 Depressive symptoms Elderly people
(n=19,420)
Cross-sectional Playing cards or Mahjong
were protective factors of
depressive symptoms
Ding et al. 2022 Cognitive function Elderly people with MCI
(n=187) without MCI
(n=489)
Cross-sectional Years of Mahjong playing
were associated with reduced
odds of having MCI
MCI, Mild cognitive impairment.
patience and politeness, as well as the importance of making
speedy decisions and gathering information. In Mahjong, one’s
action time is simply one-fourth of the game time, and the
remaining three-fourths of the time tends to be spent waiting for
the opponent’s moves. It is especially difficult for young children
to sit idle for a long time; they tend to move from their seats
as soon as they lose interest, thereby interrupting the game. For
this reason, we attempted to keep the game running smoothly
by reducing the time of one’s turn and reducing the waiting
time for the opponent. We also instructed the players to gather
information during the waiting time, analyze it, and decide their
strategy in advance. Four games were played from 10:30 to 15:00,
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TABLE 2 Clinical manifestations and life background.
Mahjong group Historical control group
n20 43
Male: female 11:09 18:25
Age at the first examination 9.54 ±2.47 7.77 ±1.90
Test-retest interval 12.45 ±1.09 10.88 ±1.22
Only child 3 N/A
Sibling participation in the Mahjong class 8 (4 pairs) N/A
Other family members who can play Mahjong 7 N/A
Playing video games (including smart phone games) 15 N/A
After-school activities
Athletic club 13 N/A
Cram school 14 N/A
Music class 4 N/A
Multiple after-school activities 7 N/A
N/A, not applicable.
two in the morning and two in the afternoon with a 30-min
lunch break in between and a time limit of 1 h per game. When
students reached the intermediate class, they played Mahjong
for free. In such cases, opponents were assigned to the same
table with people of varying abilities as much as possible. This
naturally creates a situation where those with more ability teach
those with less ability; thus, the children teach each other.
Measurement of intelligence quotient
The Wechsler Intelligence Scale for Children Fourth Edition
(WISC-IV) was used to measure the children’s IQ. WISC was
created in the United States and has been adapted for widespread
use in different cultures around the world. It is not just a
translation, but a development that takes into account language
and culture, making it one of the most adapted tests in the
world (Grégoire et al., 2008). Moreover, the WISC 3rd Edition
has been used in 12 countries, including Japan and the U.S.,
to examine cross-cultural differences in intelligence testing, and
results showed that the differences in intelligence quotients
between cultures were insignificant (Georgas et al., 2003). The
WISC-IQ is adjusted to place 50% of the population in the
90–109 range and has been revised every few years. The full-
scale IQ (FSIQ), commonly referred to as IQ, is obtained by
adding the scores of four subscales: verbal comprehension index
(VCI), perceptual reasoning index (PRI), working memory
index (WMI), and processing speed index (PRI). Each subscale
index is calculated by adding the scores of two or three core
subtests: VCI, similarity, vocabulary, and comprehension; PRI,
block design, picture concepts, and matrix reasoning; WMI,
digit span and letter-number sequencing; and PSI, sign and
symbol search (Figure 1). Since the raw scores from each core
subtest are adjusted for age to calculate the index score, if the
raw score is the same as the previous year, the IQ will decrease. In
this study, the scale was administered by a doctor who attended
a training course organized by Nihongo Bunka Kagakusha, the
publisher of the Japanese version of the WISC, and was qualified
to administer the test. All the children were able to complete the
core subtests, and no supplemental subtests were substituted.
Historical control group
In the present study, it was difficult to obtain the cooperation
of a control group; therefore, we used a historical control
group to compare the effects. The WISC has a rigorous testing
methodology; it can be compared with historical controls (Ryan
et al., 1994). However, WISC-IV has been shown to increase
with shorter test–retest periods due to practice effects (Estevis
et al., 2012). To rule out this practice effect, we used data from
Ryan et al. (2010) instead of the standardized Japanese WISC4
data in this study. The data from this literature was acceptable
as a standard sample of WISC-IV scores over time because
the participants were children without learning disabilities or
intellectual disabilities, and the test–retest interval confirmed
that there was little to no training effect (Table 2).
Procedure
Initial IQ evaluation was conducted on 35 children. Fifteen
of these children dropped out, and 20 children were evaluated 1
year later; the change in the IQ of the participants was compared
to that of the historical control group (Figure 2).
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FIGURE 1
Composition of WISC-IV. The full-test intelligence quotient with the WISC-IV consists of four subscales and a subtest consisting of 2–3 items
each.
FIGURE 2
Procedures. An initial evaluation was conducted on 35 patients, but 15 dropped out and 20 were able to complete the second evaluation. The
change in intelligence quotient of these 20 participants was compared with that of the historical control group.
Statistical analysis
R (version 3.1.3; R Foundation for Statistical Computing,
Vienna, Austria; URL http://www.R-project.org/) was used
for statistical processing. Fisher’s exact test was used for the
analysis of binary variables. For between-group comparisons
of continuous variables, a t-test statistics was conducted for
variables following a normal distribution and the Wilcoxon rank
sum test for variables not following a normal distribution. For
comparisons over time, a paired t-test was conducted. A two-
way ANOVA was conducted for comparison with the historical
control group using Prism 6 (version 6.0 g; GraphPad Software,
Inc, San Diego, USA; URL https://www.graphpad.com).
Ethical considerations
This study was approved by the Ethical Review Committee
of Yokohama City University (Ethical Review No.: B201100040).
Informed verbal and written consent to participate in the
study was obtained from all the children and their parents,
respectively. This study was conducted in accordance with the
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code of ethics set by the Declaration of Helsinki and its future
amendments or comparable standards.
Results
The mean age of the 35 participants who underwent the
initial evaluation was 9 years 4 months ±2 years 2 months
(boys =23; girls =12). The FSIQ mean was 107.29 ±13.08,
and the mean scores for the subscale indices were as follows:
VCI =105.6 ±15.02, PRI =104.89 ±12.01, WMI =103.00 ±
16.40, and PSI =105.91 ±12.92. Of the participants, 15 stopped
coming to the school after the initial evaluation, and 20 (11 boys
and 9 girls) continued to attend the Mahjong classes even after
1 year. The average FSIQ of the 15 children who dropped out
was 108.93 ±13.23; the main reasons for dropping out were
lockdown due to the COVID-19 pandemic, moving to distant
locations, and loss of interest in Mahjong.
At the time of the first evaluation, the mean age of the 20
students who continued to attend was 9 years and 6 months ±
2 years and 6 months (range: 6 years and 2 months to 14 years
and 3 months). Their mean FSIQ at the first examination was
106.05 ±13.17, and there was no difference with the children
who dropped out (p=0.53); the mean scores for the subscale
indices for these 20 children were as follows: VCI =100.60
±11.77, PRI =105.80 ±12.12, WMI =101.90 ±15.53, and
PSI =108.05 ±12.94.
During the second evaluation, their mean age was 10 years
and 7 months, and the mean interval between the tests was 12.45
months (range: 11–15 months). The mean number of times
the children participated in the Mahjong class by the second
evaluation was 16.55 ±5.30 (4–22). Most students (17/20)
attended at least 12 Mahjong classes (at least once a month).
In addition, due to the COVID-19 pandemic, few had engaged
in new after-school activities for more than 6 months. One of
the 20 students began attending a cram school, two had joined
an athletics club, and one began playing smartphone games,
mostly Mahjong. All these factors were small and difficult to
process statistically.
The mean FSIQ at the second evaluation was 113.75
±13.86; the mean scores for the subscale indices were
as follows: VCI =106.75 ±12.09, PRI =109.55 ±
11.20, WMI =105.85 ±16.849, and PSI =119.05 ±
18.07. There was a statistically significant increase in FSIQ,
VCI, and PSI scores (p<0.01) compared to the first
evaluation (Figure 3).
There were no significant differences between the
participants and the historical control group regarding the
changes in FSIQ and VCI; only changes in PSI and symbol
search showed statistically significant differences (Table 3).
In addition, groups with PSI elevated by 10% or more
compared with those without PSI. We examined the factors
in the group with elevated PSI and found that only high
WMI (>100) at the first examination was a significant factor
(p=0.02). Although there were no significant differences, PSI
was likely to be elevated in children who were female (Odds ratio
3.9, 95% CI 0.44–55.62) and who were engaged in athletic lessons
(Odds ratio 5.11, 95% CI 0.54–76.37) (Table 4).
Discussion
In this study, children who continuously participated in
the Mahjong classes for 1 year demonstrated increased IQ
scores. By subscale index, the increase in VCI and PSI was
large, whereas the increase in PSI was significant compared
with the historical control group (p=0.02). In the subtest that
defined the PSI, symbol search showed an increase of more
than 1 point and was statistically significant compared with
the historical control group (p=0.03). The historical control
group was from a different country from the mahjong group,
which could be an indication of cultural differences. However,
as noted earlier, the WISC has been adapted and widely used in
different countries, and the differences in scores across cultures
are insignificant (Georgas et al., 2003;Grégoire et al., 2008).
There is a strong correlation between WISC-III and WISC-IV,
and the Japanese and U.S. versions are very similar in their
standardized sample data. In addition, the test–retest stability
of the Japanese and U.S. versions of the WISC4 standardized
sample data is also very similar, and no significant differences
in test score changes occur even when there is a cultural
difference (Table 5) (Wechsler, 2003,2010). Takeuchi et al.
(2018) evaluated changes in intelligence quotients of Japanese
children, in general, using WISC-III. According to these studies,
although there is a negative correlation between intelligence
quotient and the amount of time spent on the Internet, little
change in the intelligence quotient itself is observed. These
findings suggest that IQ may be stable over time in standard
Japanese children in the absence of special intervention. In the
international literature, it is also known that music training
(Carioti et al., 2019), video games, and video viewing can
increase WISC scores (Soares et al., 2021). However, in the
present study, these particular types of training were also rarely
observed in a sustained manner during the observation period.
We analyzed the factors and found that two of them may be
related. The first is an increase in simple writing speed and the
second is an improvement in visual working memory. Among
the core subtests in the WISC-IV, only the two tests to define
PSI were administered in writing by subject form within a time
limit. Mahjong showed an increase in the emphasis on the eyes
and hands and improved the reaction speed and accuracy of
the hand movements (Tsang et al., 2016). Moreover, Mahjong
might enhance the eye and hand coordinated movements, which
led to an increase in symbol search scores. In particular, this
effect may be synergistic with the fact that the student is
learning athletic lessons. Although no significant differences
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FIGURE 3
Changes in intelligence quotient. Statistically significant increases were observed in the FSIQ, VCI, and PSI. PRI, Perceptual reasoning index; PSI,
Processing speed index; VCI, Verbal comprehension index; WMI, Working memory index; FSIQ, Full-scale intelligence quotient. * p≤0.01.
TABLE 3 Changes in the score of intelligence test.
Mahjong group (n=20) Historical control group (n=43)
First examination Second examination First examination Second examination
Mean SD Mean SD Mean SD Mean SD p-value
Full-scale IQ 106.05 13.17 113.75 13.86 111.63 10.71 113.26 10.4 0.07
Subscale index
Verbal comprehension index 100.6 11.77 106.75 12.09 107.84 14.69 108.09 13.53 0.14
Perceptual reasoning index 105.8 12.12 109.55 11.2 112.56 11.58 112.98 11.43 0.52
Working memory index 101.9 15.53 105.85 16.849 106.67 14.22 108.72 14.24 0.65
Processing speed index 108.05 12.94 119.05 18.07 107.4 13.01 109.86 11.72 0.02
Subtest
Similarities 10.8 1.9 12 2.3 11.16 2.81 11.67 3.23 0.32
Vocabulary 10.13 2.56 10.53 2.61 11.49 2.64 11.47 2.67 0.86
Comprehension 9.47 2.5 11.27 3.28 11.7 3.14 11.47 2.71 0.11
Block design 11.33 3.96 11.53 3.38 11.49 2.64 12.05 2.71 0.97
Picture concepts 9.73 3.24 10.53 2.42 12.16 2.48 12.33 2.34 0.54
Matrix reasoning 12.67 2.79 12.13 2.64 12.37 2.45 11.84 2.6 0.76
Digit span 9.87 2.83 10.2 3.23 10.91 2.84 11.21 2.82 0.92
Letter-number sequencing 10.73 3.73 11.67 3.52 11.76 2.72 12.07 2.75 0.55
Coding 11.53 3.04 12.6 3.94 11.23 3.18 11.47 2.67 0.48
Symbol search 12.87 2.64 14.87 3.54 11.26 2.34 11.98 2.33 0.03
IQ, Intelligence quotient.
were found in this study, the PSI tended to be particularly
elevated in children who were engaged in athletic lessons. Such
children had smooth hand movements, to begin with, and
the enhanced hand–eye coordination may have increased their
writing speed.
As symbol search was performed by visually recognizing
shapes, visual working memory was also reflected in the coarse
points. All of the working memory measured by the WISC-
IV reflects auditory working memory, which is the ability to
remember what one hears. There are a few situations in daily life
in which action selection is visually dependent. In daily life, most
of the instructions and other things that must be remembered
are obtained through hearing. Instructions obtained visually are
easier to retain in the form of images or notes, and often do not
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TABLE 4 Comparison between increased and non-increased groups of PSI.
PSI increase
More than 10% Less than 10% Odds (95% CI) p-value
N11 9
Female 6 2 3.9 (0.44–55.62) 0.2
Age at the first examination 10.10 ±2.98 9.08 ±1.98 0.37
Test-retest interval (Median; IQR) 12 (12–12) 13 (12–14) 0.07
Number of children attending the Mahjong class (Median; IQR) 21 (9–21) 16 (13.5–19.5) 0.49
Only child 1 2 2.71 (0.11–184.85) 0.57
Sibling participation 4 4 0.73 (0.08–6.1) 1
Other family members can play Mahjong 4 3 1.14 (0.13–11.13) 1
Playing video games (including smart phone games) 8 7 0.77 (0.05–8.98) 1
After-school activities
Athletic lessons 9 2 5.11 (0.54–76.37) 0.16
Cram school 7 7 0.52 (0.04–5.12) 0.65
Music lesson 3 1 2.88 (0.18–176.62) 0.59
Multiple after-school activities 3 4 0.49 (0.05–4.31) 0.64
Initial IQ tests ≥100
Full-scale IQ 9 5 3.36 (0.34–50.18) 0.34
Verbal comprehension index 7 4 2.1 (0.26–18.8) 0.65
Perceptual reasoning index 9 5 3.36 (0.34–50.18) 0.34
Working memory index 9 2 13.05 (1.28–236.66) 0.02
Processing speed index 9 6 2.16 (0.19–33.41) 0.62
PSI, Processing speed index; IQR, Interquartile range; IQ, Intelligence quotient.
require short-term memory. In Mahjong, auditory information
is essentially not needed, and almost all the information needed
for action selection is derived from vision. In the Mahjong
classes, children are taught to count, check, and memorize the
tiles on the table with their eyes so that they can make speedy
decisions when it is their turn. It is highly likely that this type
of instruction has influenced the increase in visual working
memory. Furthermore, in this study, higher initial working
memory (>100) was significantly associated with higher PSI.
This suggests that latent memory is related to visual working
memory. Children with higher initial PSI (>100) were not
associated with increasing PSI; however, children with higher
initial PSI may have encountered more situations in which they
used visual working memory. Moreover, in this study, PSI was
more likely to be elevated in women with auditory working
memory dominant over the visual in daily life (Voyer et al.,
2017). It has been pointed out that children who originally have
high IQ tend to learn better, and their IQs, including PSI, are
more likely to increase on the second WISC test (Ryan et al.,
2010). This is believed to be a training effect, in which taking
an intelligence test multiple times increases the likelihood of
higher scores; nevertheless, there was no association between
the FSIQ and the rate of increased PSI in this study. The basis
for increased PSI might be affected by latent memory, but not
by learning ability. Research shows that environmental factors
and training may be more effective in increasing IQ at a younger
age. No correlation was found between age and increased IQ in
this study. However, all participants in this study were school-
age children, and the age range was too narrow to examine
age correlations. Moreover, elevated PSI is known to occur in
teenage, and is less likely to occur later in adulthood (Pauls et al.,
2013), which may make a difference in studies with adults.
These effects cannot be obtained by playing Mahjong in a
game but may only be obtained by actually playing Mahjong
with other people. Fujimori et al. reported that increased blood
flow in the visual and language areas of the left temporal and
parietal lobes was observed while playing Mahjong (Fujimori
et al., 2015). This brain activity was not observed during the
game of Mahjong; however, it was observed during both the
actual Mahjong with and without a conversation. Mahjong
experts have also been shown to activate the primary visual
cortex when they touch Mahjong tiles, even when blind-folded
(Saito et al., 2006). This response did not occur when a non-
Mahjong player touched a Mahjong tile, nor did it occur when
a Mahjong expert touched a non-Mahjong tile, such as Braille.
Thus, playing while actually touching the Mahjong tiles may
alter the cross-modal response of the tactile and visual cortices.
Such responses of the visual cortex are also involved in the
increase of visual working memory. In addition, not just any
table game played with people will show this kind of response.
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Higashijima et al. 10.3389/fpsyg.2022.934453
TABLE 5 Japanese WISC IV comparison with United States.
Japanese WISC IV comparison with United States
Test-retest stability Correlations between WISC-IV and III
Japanese United States Japanese United States
Full-Scale IQ 0.93 0.93 0.86 0.89
Subscale index
Verbal comprehension index 0.91 0.93 0.87 0.87
Perceptual reasoning index 0.78 0.89 0.65 0.74
Working memory index 0.82 0.89 0.7 0.72
Processing speed index 0.84 0.86 0.81 0.81
Subtest
Similarities 0.85 0.86 0.75 0.76
Vocabulary 0.8 0.92 0.72 0.82
Comprehension 0.74 0.82 0.71 0.62
Block design 0.81 0.82 0.75 0.77
Picture concepts 0.63 0.76 N/A N/A
Matrix reasoning 0.64 0.85 N/A N/A
Digit span 0.87 0.83 0.75 0.77
Letter-number sequencing 0.67 0.83 N/A N/A
Coding 0.84 0.84 0.79 0.76
Symbol search 0.74 0.8 0.69 0.67
Note: IQ, Intelligence quotient; WISC, Wechsler Intelligence Scale for Children.
It has been suggested that brain activity during table games
varies with the amount of information required for the game.
In a chess-like one-on-one complete information game, which
requires relatively little information, the caudate nucleus is
mainly active (Wan et al., 2011,2012). This region is used
for computational processing, pattern recognition, and other
processes similar to deep learning by artificial intelligence. Such
brain activity seems to be more involved in learning effects
than in visual activity or language functions. Similarly, Burgoyne
et al. (2016) reported that numerical ability was more strongly
correlated with chess skills than verbal and visuospatial abilities.
In a comparison of skilled and novice Buduk players, changes
were observed in the nucleus accumbens and amygdala of the
skilled players (Jung et al., 2013). The nucleus accumbens acts
as a part of the reward system and influences the prediction and
expectation, as well as pleasure, when a reward is obtained. The
amygdala (a part of the limbic system) also plays a major role
in emotion, mainly in reading facial expressions. These findings
suggest that in Buduk, where there is more than adequate
information for pattern recognition, it is more important to
read the thoughts and facial expressions of the opponent and
predict their moves than in chess. Conversely, autism spectrum
disorders are representative of disorders in which amygdala
dysfunction is noticed (Yang et al., 2021). There are various
types of autism spectrum disorders, including ADHD and
LD, but all types are known to have reduced PSI (Sherman
et al., 2012). Research suggests that the amygdala may also be
involved in gaming addiction, which has become a problem
in recent years. In gaming addiction, a decrease in PSI is also
observed, along with VCI and FSIQ, which is contradictory to
the neuropsychological test in this study (Jang et al., 2021).
Furthermore, PSI may not reflect only the activity of these
localized areas. PSI is decreased in epilepsy (Sherman et al.,
2012) and head trauma (Rackley et al., 2012), as well as in
autism. In these disorders, the PSI is decreased independent of
the location of the brain lesion. Therefore, PSI has recently been
considered to reflect both local brain functions and extensive
brain networks. The extremely varied information processing,
including non-verbal communication, enhances the network
throughout the brain, leading to an increase in PSI.
Conclusion
This study showed that continuous participation in Mahjong
classes improved PSI. This was significant when compared to
the historical control group. The brain network may have been
strengthened by the variety of information processing tasks
in Mahjong.
Limitations
In this study, the participants were volunteers, and the
sample size for the test was small due to the prevalence of
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Higashijima et al. 10.3389/fpsyg.2022.934453
COVID-19. The statistical test power was therefore limited.
In addition, it was impossible to conduct a second test using
a group that did not participate in the Mahjong class as a
control, and the historical control was used as a standardized
sample for comparison. This control group had a different
cultural background, and the details of their education were
unclear. Therefore, comparisons should be made with caution.
Comparison with the prior literature, which is difficult to
compare, showed no significant differences in FSIQ and VCI, but
also confirmed that FSIQ and VCI were significantly increased.
Further studies with larger sample sizes and control groups are
needed to clarify that Mahjong helps improve IQ. In addition,
the Mahjong classes themselves were only held once or twice
a month. However, the frequency of playing Mahjong outside
the class, that is., the time spent playing Mahjong with friends
and family, could not be quantified. We cannot eliminate the
possibility that this is an effect of learning Mahjong by attending
Mahjong classes, rather than an effect of the Mahjong classes.
Data availability statement
The original contributions presented in the study are
included in the article/Supplementary material, further inquiries
can be directed to the corresponding author.
Ethics statement
The studies involving human participants were reviewed
and approved by Ethical Review Committee of Yokohama City
University. Written informed consent to participate in this
study was provided by the participants’ legal guardian/next
of kin.
Author contributions
TH carried out the experiment and wrote the manuscript
with support from TA. Both TH and TA contributed to the final
version of the manuscript. KS supervised the project. All authors
contributed to the article and approved the submitted version.
Funding
This work was supported by research grants from JSPS
Kakenhi (JP20K17976 to TH).
Acknowledgments
We would like to express our sincere gratitude to Yuichi
Ikeya and other staff of the Neuron Children’s Mahjong Class
and to the children and their parents who cooperated with the
evaluations during the Mahjong classes.
Conflict of interest
The authors declare that the research was conducted in the
absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the
authors and do not necessarily represent those of their affiliated
organizations, or those of the publisher, the editors and the
reviewers. Any product that may be evaluated in this article, or
claim that may be made by its manufacturer, is not guaranteed
or endorsed by the publisher.
Supplementary material
The Supplementary Material for this article can be
found online at: https://www.frontiersin.org/articles/10.3389/
fpsyg.2022.934453/full#supplementary-material
SUPPLEMENTARY FIGURE 1
Lesson outline for Children’s Mahjong Class. There were three main
levels of children’s Mahjong classes: immediately after the introductory
class, a beginner class, and an intermediate class. When the instructor
determined that it is possible to advance to the next level, the student
will advance accordingly.
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