2013. Vol.4, No.10, 736-740
Published Online October 2013 in SciRes (http://www.scirp.org/journal/psych) http://dx.doi.org/10.4236/psych.2013.410104
Copyright © 2013 SciRes.
Left-Right and Up-Down Mirror Image Confusion in 4-, 5- and
Department of Psychology, O chanomizu University, Tokyo, Japa n
Received July 24th, 2013; revised August 26th, 2013; a ccepted September 28th, 2013
Copyright © 2013 Izumi Uehara. This is an open access article distributed under the Creative Commons Attri-
bution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited.
Young children under the age of 8 - 9 years tend to confuse left-right mirror images, and it is thought that
their linguistic skills play a crucial role in this phenomenon. However, other aspects of this confusion,
such as whether children confuse up-down mirror images or whether the meaningfulness of the stimulus
influences matching performance, remain unclear. The present study examined the confusion of left-right
and up-down reversed images by 4-, 5- and 6-year-olds using meaningful and meaningless figures in a
task in which sample and comparison stimuli were presented simultaneously. Children performed more
accurately when presented with meaningful figures and confused both up-down and left-right reversed
figures, although they did so less frequently in response to up-down than to left-right reversed figures.
Reversal confusion was greatest in 4-year-olds and no significant differences were observed between 5-
and 6-year-olds. These findings suggest that the ability to discriminate reversed images may be associated
with the development of a wide range of cognitive abilities including theory of mind, executive function,
Keywords: Preschool Children; Left-Right and Up-Down Mirror Image Confusion; Meaningfulness
It is well-known that young children under 8 - 9 years of age
experience difficulty when discriminating left-right mirror im-
ages (e.g., Bryant, 1973; Cohn & Stricker, 1979; Cronin, 1967;
Davidson, 1935; Jordan & Jordan, 1974; Thompson, 1975). A
number of previous studies have used letters, such as “b” versus
“d” and “p” versus “q”, to investigate reversal discrimination
and, as a result, it is thought that there may be a correlation
between the reading and writing skills of children and their
performance on left-right reversal discrimination tasks (Cohn &
Stricker, 1979; Cubelli & Della Sala, 2009; Davidson, 1935;
Fisher, Bornstein, & Gross, 1985; Jordan & Jordan, 1974, 1990;
Terepocki, Kruk, & Willows, 2002).
McMonnies (1992a; 1992b) found that mirror image confu-
sion in children is correlated with factors other than linguistic
skills and suggested that left/right body awareness may be a
latent factor. Jean-Paul and Youssef (2012) suggested that other
tasks, such as those that require writing a letter in a specific
location on a sheet of paper, may also influence the mirror
writing of children. Furthermore, meaningfulness has some
influence on mirror image discrimination. Mandler and Stein
(1974) found that children 7 - 8 years of age recognize reversals
of meaningful pictures more accurately than expected, although
this study did not include meaningless pictures as control stim-
uli. Outside of this classic study, the relationship between the
meaningfulness of a stimulus and mirror image confusion lacks
supporting evidence and, to date, the causes of mirror image
confusion in children and the mechanisms underlying this phe-
nomenon remain unclear. Thus, it is important to explore the
possible factors other than linguistic skills such as reading and
writing, that influence mirror image confusion in preschool
children who have not yet fully developed reading and writing
A number of previous studies have used lines and figures to
investigate the discrimination of images by preschool children
(Bryant, 1973; Corballis & Zalk, 1977; Cronin, 1967; Rude1 &
Teuber, 1963; Thompson, 1975). However, the type of stimuli
that elicit confusion in preschool children and the extent of such
confusion remain ambiguous. Likewise, the discrimination of
up-down mirror images is much less documented than is
left-right reversal discrimination. Several initial studies indicate
that up-down discrimination is easier for young children than
left-right discrimination (Davidson, 1935; Huttenlocher, 1967;
Rude1 & Teuber, 1963; Thompson, 1975), but these studies do
not clarify whether preschool children confuse up-down rever-
sals in a matching-to-sample task involving novel stimuli. Ad-
ditionally, virtually no studies have investigated up-down dis-
crimination in young children. Thus, the extent to which chil-
dren confuse up-down reversed images and the age at which
such confusion occurs compared with the extent to which they
confuse left-right reversed images and the age at which that
confusion occurs remain ambiguous.
Thus, the present study examined the extent to which pre-
school children confuse original figures with left-right and
up-down reversals of these images and whether their perform-
ance in response to meaningful versus meaningless figures
differs. To compare responses to left-right and up-down re-
versed images, each child was asked to perform a simultaneous
matching-to-sample task by selecting a stimulus from a set of
comparison stimuli that included both left-right and up-down
This study included 42 4-year-olds (12 boys and 30 girls;
mean age: 4 years and 2 months; range: 3 years and 8 months to
4 years and 6 months), 41 5-year-olds (24 boys and 17 girls;
mean age: 5 years and 2 months; range: 4 years and 7 months to
5 years and 6 months), and 45 6-year-olds (26 boys and 19 girls;
mean age: 6 years and 2 months; range: 5 years and 7 months to
6 years and 6 months) from a nursery school in a suburb of a
large city near Tokyo. All were middle-class, Japanese-speak-
ing children. This study was conducted under the supervision of
the school, and written consent from the parents of participants
was obtained through the school prior to the participation of
their children. All children who participated in this study did so
voluntarily and none dropped out before the study was com-
Ten stimulus sheets (210 mm × 297 mm) were used for the
test (explained in the next section), and four were used for
practice trials that were performed before the test trials. A sam-
ple stimulus was presented in the upper half of each stimulus
sheet, and six comparison stimuli were presented in the lower
half in a 2 × 3 layout (see Figure 1). The six comparison stim-
uli were comprised of the same figure as the sample stimulus
(in the upper half), a left-right reversal of the sample stimulus,
an up-down reversal of the sample stimulus, and three figures
that appeared similar to the sample stimulus. Each of the three
figures differed from the sample stimulus in a few respects. For
example, if the sample were a shirt, one of the comparison fig-
ures would have a crooked sleeve and another would not have a
collar (Figure 1).
Thus, 10 sample stimuli and 60 (10 × 6) comparison stimuli
were used for the test trials, whereas four sample stimuli and 24
(4 × 6) comparison stimuli were used for the practice trials. The
10 sample stimuli in the test trials consisted of five meaningful
figures and five meaningless figures used by a previous study
(Uehara, 2012) in which seven elementary school children
(aged 7.6 - 9.3 years) correctly chose all the meaningful and
meaningless figures. Meaningful figures included a shirt, a cup,
and a boot, and meaningless figures were geometrical figures
Illustration of the placement of stimuli on a test sheet. A sample
stimulus was placed on the upper half of the paper, and six com-
parison stimuli were placed on the lower half. a) An example of
meaningful stimuli. b) An example of meaningless stimuli.
consisting of lines and curves (Figure 1). The four sample
stimuli in the practice trials were simple meaningless figures
and were never used in the test trials. All figures were prepared
by computer software and hard copies were used for the ex-
periment. The presentation order of the 10 test sheets was ran-
domized across participants, and the locations of the six com-
parison figures on each sheet were also randomized for each
Each participant performed the task in a quiet classroom
during his or her free time during the regular school day. Before
the test trials, each subject completed four practice trials and
received feedback after each response. By the end of the prac-
tice trials, the researcher confirmed that each participant under-
stood the task requirements: namely, to choose the figure that
looked most similar to the sample.
For the test trials, the researcher presented each child with 10
figure sheets one at a time. The researcher asked the child to
choose the comparison figure that was most similar to the sam-
ple figure by asking the child, “Which figure looks most like
this figure?” Children responded by pointing with their finger.
The test trials did not include feedback concerning the accuracy
of the response; rather, the same verbal prompt was given each
time, “Well, then, next.” All participants finished the test trials
in approximately 3 - 5 minutes.
Preliminary analyses did not reveal any sex differences in
accuracy or error type; thus, sex was not considered in the fol-
Effects of Age and Meani n gf u ln e s s o n
The mean correct response rate of the children was plotted as
a function of age and meaningfulness (Figure 2), and only an
exact match-to-sample response was considered correct. A
three (age: 4-, 5-, or 6-year-old) × two (meaningfulness: mean-
ingful or meaningless) analysis of variance (ANOVA) revealed
statistically significant main effects for age (F[2,125] = 53.7,
4-year-old 5-year-old 6-year-old
M ean percen t ag e o f corr e ct an swers
The mean correct response rate plotted as a function of age (4-year-olds,
5-year-olds, and 6-year-olds) with meaningfulness (meaningful or
meaningless figures) as a parame ter. Error bars indicate standard errors.
Copyright © 2013 SciRes. 737
p < .01, partial η2 = .46) and meaningfulness (F[1,125] = 8.79,
p < .01, partial η2 = .07). No significant interaction between age
and meaningfulness was observed (F[2,125] = .46 p > .05, par-
tial η2 = .00). Post hoc multiple comparison tests for age
(Tukey HSD, p = .05) revealed a significantly poorer perform-
ance by 4-year-olds compared with 5-year-olds and 6-year-olds
and by 5-year-olds compared with 6-year-olds. These findings
indicate that older children performed better than younger ones
and that children performed more accurately in response to
meaningful than to mea nin gless figures.
Analysis of Errors: Choice of Left-Right Mirror
To investigate whether children erroneously chose the
left-right reversed stimuli more frequently than expected by
chance (chance level: 16.7%), one-sample t-tests were con-
ducted. Children in each age group chose the left-right reversed
stimuli significantly more frequently than chance in response to
both meaningful and meaningless stimuli: 4-year-olds for
meaningful stimuli: t(41) = 7.37, p < .01; 4-year-olds for
meaningless stimuli: t(41) = 9.40, p < .01; 5-year-olds for
meaningful stimuli: t(40) = 4.40, p < .01; 5-year-olds for mean-
ingless stimuli: t(40) = 4.65, p < .01; 6-year-olds for meaning-
ful stimuli: t(44) = 4.29, p < .01; 6-year-olds for meaningless
stimuli: t(44) = 2.08, p < .05). In other words, when children
failed to choose the exact match, they chose the left-right re-
versed stimulus more frequently, regardless of meaningfulness.
Differences in the choice of left-right mirror images accord-
ing to age and meaningfulness were also assessed. The mean
response rate of the children when choosing left-right reversed
stimuli was plotted as a function of age and meaningfulness
(Figure 3). A three (age: 4-, 5-, or 6-year-old) × two (mean-
ingfulness: meaningful or meaningless) ANOVA revealed a
statistically significant main effect for age (F[2,125] = 14.8, p
< .01, partial η2 = .19) but not for meaningfulness (F[1,125] =
1.71, p > .05, partial η2 = .01) or for the interaction between
these two factors (F[2,125] = 1.94 p > .05, partial η2 = .03).
Post hoc multiple comparison tests for age (Tukey HSD, p
= .05) revealed a significantly greater number of choices of the
left-right reversed stimulus by 4-year-olds than by 5-year-olds
4-year-old 5-year-old 6-year-old
Mean percentage of left-right reversal
mean i n gless
The mean response rate of children choosing left-right reversed fig-
ures plotted as a function of age (4-year-olds, 5-year-olds, and 6-
year-olds) with meaningfulness (meaningful or meaningless figures)
as a parameter. Error bars indicate standard errors.
and 6-year-olds. No significant difference was found between
5-year-olds and 6-year-olds. These findings indicate that young
children aged 4 - 6, especially 4-year-olds, often confused fig-
ures with their left-right mirror images regardless of meaning-
Analysis of Errors: Choice of Up-Down Mirror
To investigate whether children erroneously chose the
up-down reversed stimulus more frequently than expected by
chance (chance level: 16.7%), one-sample t-tests were per-
formed. Only the 4-year-olds chose the up-down reversed
stimulus significantly more frequently than would be expected
by chance regardless of meaningfulness: for meaningful stimuli:
t(41) = 3.83, p < .01; for meaningless stimuli: t(41) = 8.02, p
< .01. The 5-year-olds and 6-year-olds chose the up-down
stimulus significantly more frequently than would be expected
by chance in response to meaningless but not meaningful stim-
uli; 5-year-olds for meaningful stimuli: t(40) = 1.53, p > .05;
5-year-olds for meaningless stimuli: t(40) = 4.39, p < .01;
6-year-olds for meaningful stimuli: t(44) = .16, p > .05;
6-year-olds for meaningless stimuli: t(44) = 5.83, p < .01. In
other words, when children failed to choose the exact match,
4-year-olds chose the up-down reversed figures more fre-
quently than expected by chance regardless of meaningfulness,
whereas 5-year-olds and 6-year-olds chose the up-down re-
versed stimulus more frequently than expected by chance only
in response to meaningless figures.
The mean response rate of children choosing the up-down
reversed stimuli was plotted as a function of age and meaning-
fulness (Figure 4). A three (age: 4-, 5-, or 6-year-old) × two
(meaningfulness: meaningful or meaningless) ANOVA re-
vealed statistically significant main effects for age (F[2,125] =
10.1, p < .01, partial η2 = .14) and meaningfulness (F[1,125] =
36.7, p < .01, partial η2 = .23). The interaction of these two
factors was not significant (F[2,125] = .38, p > .05, partial η2
= .00). Post hoc multiple comparison tests for age (Tukey HSD,
p = .05) indicated a significantly greater number of choices of
the up-down reversed stimulus by 4-year-olds compared with
5-year-olds and 6-year-olds. No significant difference was
Mean per centag e of up-dow n rever sal
me aningfu l
The mean response rate of children choosing up-down reversed figures
plotted as a function of age (4-year-olds, 5-year-olds, and 6-year-olds)
with meaningfulness (meaningful or meaningless figures) as a parame-
ter. Error bars indicate standard errors.
Copyright © 2013 SciRes.
observed between 5-year-olds and 6-year-olds. These findings
indicate that children, regardless of age, chose up-down re-
versed figures more frequently in response to meaningless than
meaningful figures and that 4-year-olds chose meaningful
up-down reversed figures more frequently than did older chil-
Analysis of Errors: Left-Right Reversed Stimuli
versus Up-Down Reversed Stimuli
The relative frequencies of choosing left-right and up-down
reversed stimuli were compared. For meaningful figures, a
three (age: 4-, 5-, or 6-year-old) × two (reversal direction:
left-right or up-down ) ANOVA revealed statistically signifi-
cant main effects for age (F[2,125] = 12.5, p < .01, partial η2
= .17) and reversal direction (F[1,125] = 33.8, p < .01, partial
η2 = .21). The interaction between these two factors was not
significant (F[2,125] = 1.14, p > .05, partial η2 = .02). Post hoc
multiple comparison tests for age (Tukey HSD, p = .05) indi-
cated a significantly greater number of choices of reversed
stimuli by 4-year-olds than by 5-year-olds and 6-year-olds, but
no significant difference was found between 5-year-olds and
6-year-olds. In other words, children, regardless of age, chose
meaningful left-right reversed figures more often than they
chose meaningful up-down reversed figures when they failed to
choose the exact match. Additionally, 4-year-olds chose both
meaningful left-right and up-down reversed stimuli more fre-
quently than did 5-year-olds and 6-year-olds.
In terms of meaningless figures, a three (age: 4-, 5-, or
6-year-old) × two (reversal direction: left-right or up-down)
ANOVA revealed a statistically significant main effect for age
(F[2,125] = 23.8, p < .01, pa rtial η2 = .28). No main effects for
reversal direction (F[1,125] = .01, p > .05, partial η2 = .00) and
no interactions between these two factors (F[2,125] = 2.02, p
> .05, partial η2 = .03) were observed. Post hoc multiple com-
parison tests for age (Tukey HSD, p = .05) indicated a signifi-
cantly greater number of choices of the up-down reversed
stimulus by 4-year-olds than by 5-year-olds and 6-year-olds,
but no significant difference was found between 5-year-olds
and 6-year-olds. In other words, the difference in the selection
of meaningless left-right and up-down reversed figures was not
significant, and 4-year-olds chose both meaningless left-right
and up-down reversed stimuli more frequently than did 5-year-
olds and 6-year-olds.
The present study investigated confusion in preschool chil-
dren when selecting left-right and up-down mirror images of
figures by including meaningful and meaningless figures within
the same paradigm. Consistent with previous studies, left-right
reversal confusion was frequently observed in children regard-
less of meaningfulness. Specifically, 4-year-olds confused
original figures with their up-down reversals regardless of
meaningfulness, whereas 5-year-olds and 6-year-olds confused
only meaningless figures. With regard to meaningful figures,
children confused the originals with their left-right reversals
more frequently than with their up-down reversals; this differ-
ence was not significant for meaningless figures. This type of
confusion was more frequently observed in 4-year-olds com-
pared with 5-year-olds and 6-year-olds, and we found no dif-
ference in the confusion of 5-year-olds and 6-year-olds.
Matching-to-sample performance improved with age between 4
and 6 years, and children performed more accurately for mean-
ingful than meaningless figures.
The present study provides new basic data and insights re-
garding reversal confusion in young children, and these data
suggest that several critical aspects of phenomenon have been
overlooked in children. First, up-down reversal confusion in
children has rarely been investigated, and knowledge concern-
ing this phenomenon is very limited. In the present study, pre-
school children confused not only left-right but also up-down
reversed images. Additionally, up-down reversal confusion
decreased earlier than did left-right reversed confusion. As
left-right reversal confusion, such as in mirror writing, is com-
monly observed when children begin to learn to write, research
tends to focus on its relationship to linguistic skills. However,
up-down reversal confusion in writing tasks has rarely been
investigated in children. The current findings suggest differen-
tial associations between up-down reversal confusion and
left-right reversal confusion, on the one hand, with linguistic
development, on the other, such that up-down confusion de-
pends on factors other than linguistic skills, such as directional
or visuospatial sense, whereas left-right confusion depends
more on linguistic skills.
Less frequent reversal confusion for meaningful relative to
meaningless figures suggests that meaningfulness influences
difficulty during the differentiation of stimuli. Thus, if children
are encouraged to find meaning in shapes or figures, they might
be less confused by reversed shapes. Previous studies indicate
that children younger than 8 - 9 years tend to confuse left-right
reversed letters. Based on the present findings, the ability to
find meaning in a word or to imagine a word from a letter may
contribute to avoidance of left-right reversal confusion. How-
ever, the ability to only pronounce and/or copy the target letter
may not be enough to reduce confusion about the left-right
reversal of a lette r.
The difference in performance between 4-year-olds and older
children suggests that the development of reversed image dis-
crimination may be related to other types of cognitive func-
tioning. Similar abilities known to be related to age differences
are theory of mind (e.g., Perner, et al., 2007; Perner & Ruffman,
1995), appearance-reality distinction (e.g., Flavell, Green, &
Flavell, 1986; Sapp, Lee, & Muir, 2000), suggestibility (e.g.,
Bruck & Ceci, 1999; Leichtman & Ceci, 1995; Uehara, 2000),
executive function (e.g., Lyons & Zelazo, 2011; Zelazo & Frye,
1998), and other functions (e.g., Gerstadt, Hong, & Diamond,
1994; Povinelli, Landau, & Perilloux, 1996; Uehara, 1998).
However, the relationships among these abilities remain unclear.
Zelazo (2004) proposed that reflective consciousness develops
together with metacognitive skills and that this development
could lead to the control of thought, emotion, and action. The
development of metacognition and/or self-reflective con-
sciousness may be one factor involved in the changes in per-
formance that have been observed over a wide range of cogni-
tive abilities, including reversal differentiation. In this manner,
the use of conscious metacognitive judgment may lead to an
avoidance of confusion when stimuli have similar appearances,
such as with reversed images. Further investigation is necessary
to elucidate the specific mechanisms underlying this process.
In conclusion, the present study demonstrates that, although
the documented relationship between left-right confusion and
linguistic skills is important, other factors also play critical
roles in reversal confusion in young children.
Copyright © 2013 SciRes. 739
Copyright © 2013 SciRes.
This research was supported by MEXT KAKENHI Grant
Numbers 19730457. I thank Ikuya Murakami for his thoughtful
comments on earlier versions of this paper and his help in sub-
mitting this paper. Most of all, I am grateful to the children and
teachers at the nursery school for their cooperation.
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