TMT Enfant
TMT Enfant
TMT Enfant
* amychan@uow.edu.au
Abstract
In this paper we report an initial validation of the Shape Trail Test–Child Version (STT-CV)
with a non-clinical sample of children aged 6 to 9 years. The STT-CV has been developed
as an age-appropriate and culturally fair direct downward extension of the Trail Making Test
a1111111111 (TMT) for the assessment of cognitive flexibility. Children completed the STT-CV and four
a1111111111
established measures of executive functions that assessed working memory, inhibitory con-
a1111111111
a1111111111 trol and task switching. Results showed the expected age-based differences in completion
a1111111111 times for both parts of the STT-CV (Trail A and Trail B). Children’s performance on the STT-
CV correlated significantly with all four measures of executive functions. After controlling for
the effects of chronological age, completion times for Trail B remained correlated with most
other measures of executive functions. These findings provide emerging evidence for the
OPEN ACCESS utility of the STT-CV, and highlight the need for designing and using appropriate variants of
Citation: Chan AYC, Morgan S-J (2018) Assessing
the TMT in the behavioural assessment of cognitive flexibility in developmentally and cultur-
children’s cognitive flexibility with the Shape Trail ally diverse populations.
Test. PLoS ONE 13(5): e0198254. https://doi.org/
10.1371/journal.pone.0198254
in performance within specific tasks (e.g., [9, 10]), as well as correlations in performance across
different tasks that purport to assess the various components of executive function [11, 12, 13].
For instance, by 2 years of age, children begin to show the ability to inhibit a prepotent
response in order to produce an alternative, task-appropriate response (e.g., [14]), with sub-
stantial improvement in such ability in the preschool period (e.g., [15, 16, 17, 18]). By 4 years
of age, children show clear evidence of their ability to engage both the storage and processing
aspects of working memory in cognitive activities [19, 20]; they also show an emergent ability
to respond to tasks that demand cognitive flexibility [20, 21, 22]. Despite evidence that the key
components of executive function are in place by early childhood, the development of the
effectiveness of these cognitive processes continues into middle childhood and beyond [3, 9,
11, 20].
Notably, in reconciling between earlier findings that suggested a lack of prefrontal functions
in preadolescents and more current findings that indicate at least partial prefrontal functioning
in early childhood, researchers are increasingly acknowledging the importance of using devel-
opmentally appropriate behavioural measures to assess the developmental trajectory of pre-
frontal skills during childhood [22, 23, 24]. A wide range of developmentally sensitive and well
established measures is available for assessing preschool children’s executive function (for an
overview of representative tasks appropriate for 2- to 6-year-old children and the relative diffi-
culties of those tasks, see [22]). Relatively few developmentally appropriate behavioural mea-
sures are available for assessing the continued improvement in different facets of executive
function in primary school age children.
In this paper, we sought to contribute to the knowledge regarding normal executive func-
tion development in childhood by reporting findings from an initial test of the Shape Trail
Test–Child Version (STT-CV)–for the assessment of cognitive flexibility of children in their
early primary school years. To foreshadow, the STT-CV is a downward extension of the Trail
Making Test–Child Version [25, 26] and reflects key features of a Shape Trail Test that has
been used as a culturally fair assessment tool of cognitive flexibility in elderly adults [27]. We
focus on the development and assessment of cognitive flexibility because this component of
executive function is expected to be supported by the more basic cognitive processes of inhibi-
tory control and working memory [1, 28]. Inasmuch as other behavioural measures have been
devised to assess behaviours associated with cognitive flexibility development (for a review, see
[1]), we reason that the STT-CV may be a culturally fair, developmentally appropriate, as well
as time- and cost-effective tool that can provide additional information on the development of
cognitive flexibility in childhood, to complement other existing measures of this construct.
a few minutes to administer. The original Adult Version of the TMT entails drawing pencil
lines quickly and accurately to sequentially connect a set of 25 encircled numbers that are ran-
domly arranged on a page. In the first task, the circles have the numbers 1 to 25 embedded in
them (Trail A). In a second task (Trail B), the circles contain the numbers 1 to 13 and the let-
ters A to L, and the task requires connecting the numbers and letters in alternating order (1-A-
2-B, . . . etc.). The Children’s Version of the TMT has been designed for children 9 to 14 years
of age, and it contains 15 circles in both parts to reduce the complexity of the visual search
required (i.e., the numbers 1 to 15 for Trail A, and the numbers 1 to 8 and the letters A to H
for Trail B) [31].
A key merit of the TMT is the simplicity of its task instructions and time efficiency of
administration, thus allowing it to be incorporated into a larger battery of measures to assess
executive function more comprehensively. As an example of its utility, Trail B has been shown
to correlate significantly with other measures of cognitive flexibility that may require longer
task administration time (e.g., percentage of perseverative errors in the Wisconsin Card Sort-
ing Task–[32]). Furthermore, reliable difference in TMT performance has been shown
between individuals with brain damage and normal controls, both in adults [33] and children
[25].
Despite its simplicity and utility, successful and efficient completion of the TMT requires
the abilities to: (i) automatically recognise the symbolic significance of numbers and letters,
(ii) visually scan the page continuously to identify relevant target stimuli, (iii) integrate the
numerical and alphabetical series flexibly, and (iv) complete task requirements under the pres-
sure of time [31]. At least by the middle primary school years, children in an English-speaking
environment can be expected to have fully mastered the symbolic significance of the English
alphabet and its applications so that they can recall it effortlessly while completing tasks such
as the TMT. However, for younger primary school children and individuals with limited
English language proficiency, their performance in Trail B would presumably reflect a combi-
nation of their efficiency in mental flexibility as well as their development in other aforemen-
tioned areas crucial for successful TMT task completion. Indeed, some studies have involved
administering the Child Version of the TMT to 6-year-old children [34] or the Adult Version
of the TMT to children [35], and have yielded rather slow task completion times, particularly
for Trail B. Such results highlight the need for an appropriate further downward extension of
the TMT and to validate it with children in their early to middle primary school years.
The Color Trails Test [36, 37] and Shape Trails Test (STT; [27]) have been designed to be
culturally unbiased analogues of the traditional TMT. Part 1 of both of these tests are similar to
Trail A in the traditional TMT. Part 2 of the Color Trails Test requires the test taker to connect
numbers embedded in circles in two alternating colours (pink and yellow–e.g., Pink 1 –Yellow
2 –Pink 3 –Yellow 4, . . . etc.); and Part 2 of the STT requires connecting numbers embedded
in two alternating shapes (circles and squares–e.g., Circle 1 –Square 2 –Circle 3 –Square 4, . . .
etc.). Zhao et al. [27] propose that the STT is in line with the Color Trails Test as a time-effi-
cient assessment tool for task switching competence; but given that the STT instead requires
test takers to join two sets of numbered dots that are enclosed by squares and circles, the STT
has the added benefit that it does not require test takers to have good colour vision, nor does it
require test administrators to have access to colour printing to produce the stimuli. Perfor-
mance in the Color Trails and STT has been shown to be significantly correlated to each other
[27].
Zhao et al. [27] provided an initial validation of the STT with a large sample of elderly Chi-
nese adults, and demonstrated that completion times for Parts A and B of the STT reliably dif-
fered across cognitively normal controls, patients with amnesic mild cognitive impairment
and patients with Alzheimer’s Disease. Furthermore, these authors provided some evidence
that the STT might be harder than the TMT or the Color Trail Test, and highlighted the need
for further validation studies on the STT.
A notable departure of Part 2 of the Color Trails and STT from the traditional TMT is that
in these tests, the display for Part 2 contains duplicates of every number in the first part, with
each number embedded with both yellow and pink circles (Color Trails) and a square and a
circle (STT). Thus in Part 2 of these tests, the visual scanning requirement is substantially
increased because the test taker has to scan for correct responses efficiently from a visually
more complex display that contains twice as many stimuli as that in Part 1. Hence, the greater
time taken to complete Part 2 may not only represent switch cost, but also extra time taken to
scan for appropriate stimuli in the more complex display.
a greater consciousness of errors. Second, Davidson et al. [20] have noted that when young
children and adults are subjected to the same executive function tasks, effects seen in differ-
ences in response times in adults are typically manifested as the same effects seen in differences
in accuracy in young children. These authors therefore highlighted the importance of examin-
ing both speed and accuracy of children’s executive function task performance where possible.
Consequently, within the inhibitory control and card sort tasks in the present study, we used a
composite performance index (“scaled completion time”–see Method for further details) that
took into account different “grades” of accuracy in children’s responses, as well as their time
efficiency of task completion.
We hypothesised that:
H1a: Children would show a switch cost when the task requires alternating between num-
bered dots enclosed by squares and circles (Trail B) as opposed to joining numbered dots
enclosed by circles only (Trail A) (i.e., completion time for Trail B would be longer than that
for Trail A); and
H1b: The switch cost in completing the STT-CV would reduce with age.
H2: Children’s performance in the STT-CV would correlate significantly with their perfor-
mance in other executive function measures (working memory, inhibitory control and another
task switching measure).
Method
Participants
This study was part of a larger research project on cognitive and emotional development. The
sample comprised 68 children who were recruited either from one school in central western
New South Wales (n = 22) or through social media (n = 46). There were 17 children aged 6
years (M = 75.94 months, SD = 3.47, 6 girls, 11 boys); 17 children aged 7 years (M = 89.53
months, SD = 2.92, 10 girls, 7 boys); 19 children aged 8 years (M = 101.53 months, SD = 2.59,
14 girls, 5 boys); and 15 children aged 9 years (M = 112.67 months, SD = 3.52, 8 girls, 7 boys).
Potential participants’ parents were contacted via the school and social media platforms to
invite children aged 6 to 9 years for their voluntary participation. All children who met the age
criterion and returned a signed parental consent form were included in the study. The study
was further explained verbally in age-appropriate terms to each child at the outset of each ses-
sion, and verbal consent was gained from each child before participation in each session. All
children spoke fluent English and only one child spoke a second language (Japanese) in addi-
tion to English. This study was approved by the University of Wollongong Human Research
Ethics Committee (research protocol HE16/065).
Day/Night task [15]. The experimenter verified that the participant associated the sun
with daytime and the moon with night-time. The participant was then shown a black card
with a white moon and stars on it, and was instructed that each time they saw this card they
were to say ‘day’. They were then shown a white card with a yellow sun on it and were
instructed that each time they saw this card they were to say ‘night’. Two practice trials fol-
lowed in which the child was shown one of each card. All children answered correctly without
the need for the experimenter to repeat the rules for each card and the practice trials. Follow-
ing this, 16 test trials were run in a fixed random order with no feedback on errors, and the
total time taken (to the nearest hundredth of a second) to complete all 16 trials was recorded.
To calculate accuracy scores for the Day/Night Task, participants received a score of 0 for an
incorrect response, 1 for a response that was initially incorrect but subsequently self-corrected,
and 2 for a correct response. Scores for the trials were then summed to create a composite
score with a maximum possible total of 32. We calculated an overall index of task performance
by dividing the total completion time by the composite accuracy score on this task (scaled
completion time). Thus a lower score would indicate better performance.
Counting span test [40]. This test comprised five levels with each level containing three
sets of items. The items for this test were white cards on which were printed red dots (the tar-
get items) along with yellow, green and blue distractor dots. There were 18 dots randomly
placed on each card, with between 2 to 6 of these dots red. The card sets varied in size from
one card per set (Level 1) to five cards per set (Level 5). The participant was required to count
the red dots only on each card by pointing to the dots and counting aloud. After the participant
counted the dots, each card was turned face down and the next card in the set was presented
for counting. After the last card in the set was turned face down, the participant was asked to
recall the number of dots counted on each card in order from first card to last. To proceed to
the next level, the participant had to have correctly recalled at least two of the three sets com-
prising the preceding level. Responses were scored as 0 for an incorrect response, and 1 for a
correct response on each trial. The scores for each trial were then summed to create a compos-
ite accuracy score with a maximum possible total of 15.
Digit Span Backward [39]. The Digit Span Backward subtest of the Australian version of
the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV; [39]) was used. In this
task, the participant listened to the experimenter reading a sequence of digits out loud (e.g. 6,
8) and then was to repeat the sequence of numbers backwards out loud (the correct response
would be 8, 6) to the experimenter. This task comprised 8 levels with two trials per level. Levels
1 and 2 consisted of two numbers per trial; level three trials comprised three numbers per trial;
finishing with eight-number sets in the level eight trials. The task was discontinued if the par-
ticipant was incorrect on both trials on a level. Responses were scored as 0 for an incorrect
response, and 1 for a correct response on each trial, with scores for each trial then summed to
create a composite accuracy score with a maximum possible total of 16.
Card sort task [15]. The participant was shown two same-sized silver boxes with slots cut
into the lids. One box had a picture of a red rabbit attached and the other had a picture of a
blue boat attached. The experimenter then produced a stack of five cards depicting red rabbits,
blue rabbits, red boats, and blue boats. The participant was instructed to sort all of the cards
according to their shape, with rabbits going into the rabbit container and boats going into the
boat container. After demonstrating with one of each card, the experimenter asked the partici-
pant to sort five cards in a fixed set order. Errors were not corrected, but were recorded and
scored as per the Day/Night task. The total time taken (to the nearest hundredth of a second)
to sort the cards was also recorded. Afterwards, the experimenter asked the participant to sort
the cards by colour: all the blue cards into the blue box and all of the red cards into the red
box. Five post switch trials then followed with the experimenter recording errors and the total
time taken to sort the cards in the same manner as for the pre-switch trials. Scores for the
responses were summed for each of the pre- and post-switch trials to form a composite accu-
racy score for pre-switch trials and for post switch trials, each with a maximum possible score
of 10 (indicating 5 correct answers). For this task, we focussed on children’s performance on
the post-switch trials. As per the Day/Night task, we calculated an overall performance index
of the Card Sort task (scaled completion time) by dividing participants’ completion time by
their accuracy score on post-switch trials.
Shape Trail Test–child version (STT-CV; adapted from [27]). The STT-CV has been
adapted specifically for this study to produce a child version by mirroring the number and
position of items in the child version of the TMT [31]. This test requires basic numerical
knowledge but does not require any knowledge of the English alphabet. The STT-CV com-
prises two trails printed on A4-size sheets; Trail A and Trail B. Trail A is identical to Part A of
the Child Version of the TMT, which displays a sequence of numbers from 1 to 15, with each
number enclosed by a small circle. Trail B (S1 Fig) displays the numbers 1 through 8 enclosed
by small circles and the numbers 1 through 7 enclosed by small squares.
Instructions were given to the participant as per the instruction manual for the TMT–Child
Version [31] and the participant completed a sample page for Trail A containing eight items, the
experimenter stopping the participant for corrections if they made any mistakes. Participants
were then asked to complete Trail A as quickly as possible while trying not to make any mistakes.
The time taken to complete the trail (to the nearest hundredth of a second) was recorded.
Afterwards, the experimenter showed a sample page for Trail B containing eight items to
the participant to complete, informing the participant that that the rules have now changed
and they were now to draw a line alternating between the circles and squares in sequential
numerical order (1 in the circle, 1 in the square, 2 in the circle, 2 in the square, . . . etc.). The
experimenter stopped the participant for corrections if they made any mistakes. Participants
then completed Trail B, working as quickly as possible while trying not to make any mistakes.
The time taken to complete the trail (to the nearest hundredth of a second) was recorded.
Results
The pattern of children’s performance in Trail A and Trail B of the STT-CV is shown in Fig 1.
Table 1 shows the descriptive statistics on children’s performance on all other measures in the
present study. As expected, older children performed better than younger children on all tasks.
There was a statistically significant effect of age group on the key performance index for each of
the Day/Night task [F(3, 64) = 10.72, p < .001, η2 = .33], Backward Digit Span task [F(3, 64) =
4.79, p = .004, η2 = .18], Counting Span task [F(3, 64) = 7.05, p < .001, η2 = .25], and Card Sort
task [F(3, 64) = 3.43, p = .02, η2 = .14]. Notably, as per the scaled completion time data for the
Card Sort task, younger children were less efficient in accomplishing the same ceiling-level
accuracy compared to their older counterparts. By comparison, for the Day/Night task, while
6-year-old children were slower in their responses and showed relatively high proportions of
incorrect and self-corrected responses, children at the older age levels showed predominantly
correct and self-corrected responses and completed the task more efficiently (see Table 1).
In the STT-CV, both Trail A and Trail B showed the predicted decrease in completion
times with age. To test for an age-related reduction in the switch cost in completing the two
parts of the STT-CV, we conducted a 4 (age group) x 2 (STT trial) mixed design analysis of var-
iance (ANOVA) on participants’ completion times for Trail A and Trail B. As predicted, the
main effects of age group [F(3,64) = 23.56, p < .001, η2p = .53] and STT trial [F(1,64) = 162.64,
p < .001, η2p = .72] were both statistically significant. Averaged across age groups, children
were faster in completing Trail A (M = 25.55 secs, SD = 9.52) than Trail B (M = 44.00 secs,
Fig 1. Mean completion times for Trail A and Trail B in the Shape Trail Test–child version for each age group.
Error bars indicate one standard error of the mean.
https://doi.org/10.1371/journal.pone.0198254.g001
Table 1. Summary of means [and standard deviations] for the major study variables.
Age group
6 Years 7 Years 8 Years 9 Years
(n = 17) (n = 17) (n = 19) (n = 15)
Day/Night task
Completion time (secs) 32.34 (3.70) 26.89 (5.09) 26.13 (4.01) 22.98 (2.58)
Accuracy 26.35 (4.87) 29.59 (1.97) 29.47 (3.01) 29.73 (2.69)
Proportion of responses
Incorrect .11 (.12) .03 (.04) .04 (.08) .02 (.05)
Self-corrected .13 (.12) .08 (.07) .09 (.08) .11 (.10)
Correct .76 (.20) .88 (.09) .88 (.12) .88 (.13)
Scaled completion time 1.29 (.42) .91 (.18) .91 (.24) .79 (.16)
BDS accuracy 4.53 (1.33) 5.65 (1.54) 6.58 (2.29) 6.33 (1.54)
Counting span accuracy 6.82 (1.38) 8.47 (2.03) 9.21 (2.15) 9.67 (1.99)
Card sort task
Pre-switch trials
Completion time (secs) 8.24 (3.34) 6.71 (1.91) 6.48 (1.98) 5.50 (1.42)
Accuracy 9.88 (.33) 9.71 (.59) 9.89 (.32) 9.80 (.56)
Post-switch trials
Completion time (secs) 7.83 (3.27) 6.39 (2.15) 5.55 (1.52) 5.04 (1.77)
Accuracy 9.71 (.99) 9.94 (.24) 9.63 (1.38) 9.87 (.35)
Proportion of responses
Incorrect .01 (.05) .00 (.00) .03 (.14) .00 (.00)
Self-corrected .04 (.11) .01 (.05) .01 (.05) .03 (.07)
Correct .95 (.15) .99 (.05) .96 (.14) .97 (.07)
Scaled completion time .84 (.45) .65 (.24) .60 (.25) .51 (.18)
BDS = Backward Digit Span task; Scaled completion time = Completion time divided by accuracy score
https://doi.org/10.1371/journal.pone.0198254.t001
Table 2. Summary of means, standard deviations, and intercorrelations [and 95% confidence intervals] for age and performance indices on inhibitory control,
working memory and cognitive flexibility measures.
M SD 2 3 4 5 6 7
1. Age (in months) 94.59 13.82 -.52 .37 .49 -.40 -.69 -.59
[-.63, -.45] [.19, .55] [.29, .65] [-.54, -.25] [-.78, -.58] [-.71, -.46]
2. Day/Night 0.98 0.33 - -.37 -.39 .39 .46 .53
[-.48, -.25] [-.54, -.22] [.13, .63] [.30, .65] [.30, .70]
3. BDS accuracy 5.78 1.88 - .48 -.30 -.41 -.47
[.23, .66] [-.51, -.04] [-.56, -.23] [-.61, -.30]
4. Counting span accuracy 8.53 2.16 - -.27 -.55 -.43
[-.42, -.11] [-.69, -.40] [-.48, -.27]
5. Card Sort 0.65 0.32 - .47 .42
[.14, .70] [.12, .65]
6. STT-CV Trail A 25.55 9.52 - .71
[.56, .84]
7. STT-CV Trail B 44.00 17.96 -
BDS = Backward Digit Span task; STT-CV = Shape Trail Test—Child Version
p < .01
p < .05
https://doi.org/10.1371/journal.pone.0198254.t002
SD = 17.96). These main effects were qualified by a significant age group x STT trial interaction,
[F(3,64) = 6.05, p = .001, η2p = .22]. Pairwise comparisons between Trail A time and Trail B
time within each age group (with Bonferroni-adjusted α at .05) indicated that for all age groups,
children took significantly longer to complete Trail B than they did for Trail A (all ps < .001).
More importantly, as age level increased, there was a general reduction in the mean difference
between the completion times for Trail A and Trail B (see means in Fig 1). These findings were
in support of H1.
Next, we examined the correlations among age and children’s performance on the STT-CV
and other executive function measures. To account for the relatively small sample size of the
present study, we used a bootstrapping procedure [41] with 1000 iterations to generate the bias
corrected and accelerated (BCa) 95% confidence interval for each correlation.
The results are shown in Table 2. Children’s performance on all of our executive function-
ing measures was significantly correlated with one another in the expected direction. Not sur-
prisingly, age was significantly correlated with performance on all measures in our study.
Comparing our two task switching measures (i.e., Card Sort and the STT-CV), the STT-CV
variables correlated more strongly with performance on the Day/Night, Backward Digit Span
and Counting Span tasks.
We conducted a further correlation analysis on the relationships among the executive func-
tioning variables after controlling for variability associated with children’s chronological age.
The partial correlations (see Table 3) indicated that Trail B completion time remained signifi-
cantly correlated with performance in the Day/Night and Backward Digit Span tasks, and its
correlation with performance in the Counting Span task was marginally significant. However,
Trail A completion time and Card Sort task performance were no longer correlated with the
other executive function measures. On the basis of the bootstrapped confidence intervals (refer
to Table 3), the correlations of Card Sort task performance with Trail A and Trail B completion
times were not statistically reliable either. These findings thus provided partial support for H2.
Discussion
The Shape Trail Test has been identified as a time-efficient and culturally fair analogue of the
traditional TMT in the assessment of task switching competence, a core component of
Table 3. Summary of partial intercorrelations [and 95% confidence intervals] for performance indices on inhibitory control, working memory and cognitive flexi-
bility measures.
2 3 4 5 6
1. Day/Night -.22# -.18 .23# .18 .33
[-.38, -.05] [-.35, .04] [-.01, .48] [-.01, .35] [.03, .53]
2. BDS accuracy - .36 -.18 -.22# -.33
[.07, .57] [-.40, .10] [-.42, -.01] [-.50, -.15]
3. Counting span accuracy - -.09 -.35 -.21#
[-.26, .07] [-.57, -.06] [-.38, -.03]
4. Card Sort - .29 .25
[-.06, .60] [-.11, .52]
5. STT-CV Trail A - .52
[.29, .72]
6. STT-CV Trail B -
BDS = Backward Digit Span task; STT-CV = Shape Trail Test—Child Version
p < .01
p < .05
# p < .10
https://doi.org/10.1371/journal.pone.0198254.t003
executive function [18]. In the present study, we developed and tested a child version of the
STT that included key features of the adult version of the STT while also preserving important
features of the child version of the traditional TMT. Consistent with previous research on the
STT [27], the development of the STT-CV has been guided by the assumption that by 6 years
of age, children are competent in discriminating between basic geometric shapes (square vs.
circle) and that they have developed basic numerical literary for counting. Normally develop-
ing 6- to 9-year-old children showed reliable age-based differences in performance on both
Trail A and Trail B of the STT-CV. As expected, the switch cost in completion time from Trail
A and Trail B decreased as age increased. Our data suggest that the STT-CV may be a valid
assessment task to observe the development of task switching competence in the early school
years. Furthermore, children’s performance in the STT-CV correlated significantly with mea-
sures of working memory, inhibitory control and task switching, thus providing early evidence
of the construct validity of the STT-CV.
However, we also found that once children’s chronological age was statistically controlled
for, some of the observed correlations were no longer statistically reliable. Although this find-
ing may simply highlight the influence of general age-related gains in executive function
competence on children’s performance across various relevant measures, the diminished cor-
relation between the STT-CV and the card sort task was somewhat unexpected, because both
tasks were supposed to measure children’s cognitive flexibility via their task switching perfor-
mance. When age-based variations in task performance was statistically controlled for and a
more stringent criterion for assessing the reliability of correlations was used (i.e., using boot-
strapped confidence intervals), the positive relationships of children’s STT-CV performance in
Trail A and Trail B with their performance on the Card Sort task was no longer clearly evident.
A potential explanation is that the small number of items included in the card sort task might
have restricted the range of observable individual differences in this task. Further validation
studies are needed to determine the relationship of the STT-CV with other developmentally
appropriate measures of children’s cognitive flexibility. This could potentially involve a modi-
fied version of the card sort task that includes additional pre-switch and post-switch items, to
enable more scope for individual differences in responding to be adequately captured (e.g.,
[3]). It would be beneficial to assess children’s performance on the STT-CV against other
established indices of cognitive flexibility also (e.g., the number of perseverative errors on the
Wisconsin Card Sorting Task).
A limitation of the present study was that we did not concurrently assess children’s perfor-
mance on the STT-CV against that on other trails tests such as the Color Trails or the child
version of the traditional TMT. However, it is noteworthy that children across all age levels
within our sample could fully understand the task instructions and successfully completed
both parts of the STT-CV, with both parts of this task showing expected individual differences
within and across the four age levels. Moreover, Trail A and Trail B completion times for our
subsample of 9-year-old children (see full data set in S1 File) were consistent with the distribu-
tions of completion times for normally developing 9- to 14-year-old children on the child ver-
sion of the TMT (see [25]). The requirement for further validation of the STT-CV
notwithstanding, our data provide initial evidence that the STT-CV may be a useful direct
downward extension of the child version of the TMT. Further research is warranted to exam-
ine the psychometric properties of the STT-CV more closely. Another limitation was that the
present study involved a relatively small convenience sample of Australian children. We did
not gather information on each child’s ethnicity or the family’s socioeconomic status.
Although we did not expect these factors to influence children’s performance on the STT-CV,
further research is needed to establish the population-based and cross-cultural generalisability
of the current findings.
An implication of the current findings is that the STT-CV may provide a sensitive measure
of children’s developing cognitive flexibility in a way that is intended in the traditional TMT.
This is because this variant of the traditional TMT does not have extra visual search demands
or assume immediate recognition of the symbolic significance of the English alphabet. There-
fore the switch cost from Trail A to Trail B cannot be attributed to difficulties with cognitive
demands beyond those required for monitoring and shifting.
A further implication of our findings is that the STT-CV has the potential to be included as
part of a larger test battery for the behavioural assessment of executive function development.
There is substantial theoretical interest in the operationalisation of the cognitive flexibility con-
struct in behavioural paradigms (e.g., [28]). Furthermore, there is practical interest in the roles
of components of executive function in other important areas of development such as mathe-
matics skills [2, 3] and major health and wealth outcomes later in life [42]. All of these avenues
of enquiry would typically entail children being assessed on multiple tasks that index the rela-
tionship between relevant executive function components and criterion variables. All else
being equal, it would be desirable to include briefer tasks that can help to keep the length of
the testing procedure as short as possible. In this paper, we have provided emerging evidence
that the STT-CV is an effective assessment tool to complement the traditional TMT to chart
the development of cognitive flexibility from the early school years onwards. Further research
is needed to replicate the present findings with a larger sample, and to develop appropriate age
norms for the STT-CV. Furthermore, given that the STT-CV has a simple task format that
children can readily understand, it would be useful to explore the appropriateness of the
STT-CV for assessing task switching performance in children younger than 6 years of age also.
In summary, our results suggest that the STT-CV is a meaningful assessment tool of the
development of cognitive flexibility in the early school years. This task may complement the
traditional TMT and other available measures to contribute to knowledge on children’s grow-
ing ability to monitor and shift their responses flexibly as per current task demands. Closer
examination in further research is required to establish the utility of this task in assessing the
development of cognitive flexibility in normally developing children across different cultural
and education backgrounds, as well as in clinical populations.
Supporting information
S1 Fig. Trail B of the Shape Trail Test–child version.
(PDF)
S1 File. Raw data file for the present study.
(XLSX)
Acknowledgments
The authors would like to thank the participants and their parents for donating their time and
consenting to participate.
Author Contributions
Conceptualization: Amy Y. C. Chan, Sarah-Jane Morgan.
Data curation: Sarah-Jane Morgan.
Formal analysis: Amy Y. C. Chan, Sarah-Jane Morgan.
Funding acquisition: Amy Y. C. Chan.
Investigation: Sarah-Jane Morgan.
Methodology: Amy Y. C. Chan, Sarah-Jane Morgan.
Project administration: Amy Y. C. Chan, Sarah-Jane Morgan.
Resources: Amy Y. C. Chan, Sarah-Jane Morgan.
Supervision: Amy Y. C. Chan.
Validation: Amy Y. C. Chan, Sarah-Jane Morgan.
Visualization: Amy Y. C. Chan.
Writing – original draft: Amy Y. C. Chan.
Writing – review & editing: Amy Y. C. Chan, Sarah-Jane Morgan.
References
1. Diamond A. Executive functions. Annual Review of Psychology. 2013; 64: 135–168. https://doi.org/10.
1146/annurev-psych-113011-143750 PMID: 23020641
2. Bull R, Scerif G. Executive functioning as a predictor of children’s mathematics ability: Inhibition, switch-
ing and working memory. Developmental Neuropsychology. 2001; 19: 273–293. https://doi.org/10.
1207/S15326942DN1903_3 PMID: 11758669
3. Van der Ven SHG, Kroesbergen EH, Boom J, Leseman PPM. The development of executive functions
and early mathematics: A dynamic relationship. British Journal of Educational Psychology. 2012; 82:
100–119. https://doi.org/10.1111/j.2044-8279.2011.02035.x PMID: 22429060
4. Carlson SM, Wang TS. Inhibitory control and emotion regulation in preschool children. Cognitive Devel-
opment. 2007; 22: 489–510. https://doi.org/10.1016/j.cogdev.2007.08.002
5. Diamond A. Normal development of prefrontal cortex from birth to young adulthood: Cognitive functions,
anatomy, and biochemistry. In Stuss D and Knight R (Eds.) Principles of Frontal Lobe Function. 2002:
Oxford University Press: New York, NY.
6. Welsh MC, Pennington BF, Groisser DB. A normative-developmental study of executive function: A
window on prefrontal function in children. Developmental Neuropsychology. 1991; 7: 131–149.
7. Bell MA, Fox NA. The relations between frontal brain electrical activity and cognitive development dur-
ing infancy. Child Development. 1992; 63: 1142–1163. PMID: 1446545
8. Giedd JN, Blumenthal J, Jeffries NO, Castellanos FX, Liu H, Zijdenbos A, et al. Brain development dur-
ing childhood and adolescence: A longitudinal MRI study. Nature Neuroscience. 1999; 2: 861–863.
https://doi.org/10.1038/13158 PMID: 10491603
9. Dick AS. The development of cognitive flexibility beyond the preschool period: An investigation using a
modified Flexible Item Selection Task. Journal of Experimental Child Psychology. 2014; 125: 13–34.
https://doi.org/10.1016/j.jecp.2014.01.021 PMID: 24814204
10. Lee NR, Wallace GL, Raznahan A, Clasen LS, Giedd JN. Trail making test performance in youth varies
as a function of anatomical coupling between the prefrontal cortex and distributed cortical regions. Fron-
tiers in Psychology. 2014; 5: 144–157. https://doi.org/10.3389/fpsyg.2014.00144
11. Brocki KC, Bohlin G. Executive functions in children aged 6 to 13: A dimensional and developmental
study. Developmental Neuropsychology. 2004; 26: 571–593. https://doi.org/10.1207/
s15326942dn2602_3 PMID: 15456685
12. Levin HS, Culhane KA, Hartmann J, Evankovich K, Mattson AJ, Harward H., et al. Developmental
changes in performance on tests of purported frontal lobe functioning. Developmental Neuropsychol-
ogy. 1991; 7: 377–395.
13. McClelland MM, Cameron CE, Duncan R, Bowles RP, Acock AC, Miao A, et al. Predictors of early
growth in academic achievement: The head-toes-knees-shoulders task. Frontiers in Psychology. 2014;
5: 300–313. https://doi.org/10.3389/fpsyg.2014.00300
14. Carlson SM, Mandell DJ, Williams L. Executive function and Theory of Mind: Stability and prediction
from ages 2 to 3. Developmental Psychology. 2004; 40: 1104–1122. https://doi.org/10.1037/0012-
1649.40.6.1105 PMID: 15535760
15. Carlson SM, Moses LJ. Individual differences in inhibitory control and children’s theory of mind. Child
Development. 2001; 72: 1032–1053. PMID: 11480933
16. Diamond A, Taylor C. Development of an aspect of executive control: Development of the abilities to
rembmer what I said and to “Do as I say, not as I do.” Developmental Psychobiology. 1996; 29: 315–
334. https://doi.org/10.1002/(SICI)1098-2302(199605)29:4<315::AID-DEV2>3.0.CO;2-T PMID:
8732806
17. Gerardi-Caulton G. Sensitivy to spatial conflict and the development of self-regulation in children 24–36
months of age. Developmental Science. 2000; 3: 397–404.
18. Kochanska G, Murray KT, Harlan ET. Effortful control in early childhood: Continuity and change, ante-
cedents, and implications for social development. Developmental Psychology. 2000; 36: 220–232.
https://doi.org/10.1037/0012-1649.36.2.220 PMID: 10749079
19. Alloway TP, Gathercole SE, Pickering SJ. Verbal and visuospatial short-term and working memory in
children: Are they separable? Child Development. 2006; 77: 1698–1716. https://doi.org/10.1111/j.
1467-8624.2006.00968.x PMID: 17107455
20. Davidson MC, Amso D, Anderson LC, Diamond A. Development of cognitive control and executive
functions from 4 to 13 years: Evidence from manipulations of memory, inhibition, and task switching.
Neuropsychologia. 2006; 44: 2037–2078. https://doi.org/10.1016/j.neuropsychologia.2006.02.006
PMID: 16580701
21. Burns P, Riggs KJ, Beck SR. Executive control and the experience of regret. Journal of Experimental
Child Psychology. 2012; 111: 501–515. https://doi.org/10.1016/j.jecp.2011.10.003 PMID: 22115451
22. Carlson SM. Developmentally sensitive measures of executive function in preschool children. Develop-
mental Neuropsychology. 2005; 28: 595–616. https://doi.org/10.1207/s15326942dn2802_3 PMID:
16144429
23. Anderson P. Assessment and development of executive function (EF) during childhood. Child Neuro-
psychology. 2002; 8:71–82. 0929-7049/02/0802-071 https://doi.org/10.1076/chin.8.2.71.8724 PMID:
12638061
24. Macdonald JA, Beauchamp MH, Crigan JA, Anderson PJ. Age-related differences in inhibitory control
in the early school years. Child Neuropsychology. 2014; 20: 509–526. https://doi.org/10.1080/
09297049.2013.822060 PMID: 23909718
25. Reitan RM. Trail Making Test results for normal and brain-damaged children. Perceptual and Motor
Skills. 1971; 33: 575–581. https://doi.org/10.2466/pms.1971.33.2.575 PMID: 5124116
26. Reitan RM, Wolfson D. Neuropsychological Evaluation of Older Children. 1992: Neuropsychology
Press: South Tucson, Arizona.
27. Zhao Q, Guo Q, Li F, Zhou Y, Wang B, Hong Z. The Shape Trail Test: Application of a new variant of
the Trail Making Test. PLoS ONE. 2013; 8(2): e57333. https://doi.org/10.1371/journal.pone.0057333
PMID: 23437370
28. Dajani DR, Uddin LQ. Demystifying cognitive flexibility: Implications for clinical and developmental neu-
roscience. Trends in Neurosciences. 2015; 38: 571–578. https://doi.org/10.1016/j.tins.2015.07.003
PMID: 26343956
29. Grant DA, Berg E. A behavioral analysis of degree of reinforcement and ease of shifting to new
responses in Weigl-type card-sorting problem. Journal of Experimental Psychology. 1948; 38, 404–
411. PMID: 18874598
30. Zelazo PD, Müller U, Frye D, Marcovitch S. The development of executive function in early childhood.
Monographs of the Society for Research in Child Development. 2003; 68: Serial No. 274.
31. Reitan RM. Trail Making Test: Manual for Administration and Scoring. 1992: Reitan Neuropsychology
Laboratory: South Tucson, Arizona.
32. Kortte KB, Horner MD, Windham WK. The Trail Making Test, Part B: Cognitive flexibility or ability to
maintain set? Applied Neuropsychology. 2002; 9: 106–109. https://doi.org/10.1207/
S15324826AN0902_5 PMID: 12214820
33. Reitan R. Validity of the Trail Making Test as an indicator of organic brain damage. Perceptual and
Motor Skills. 1958; 8: 271–276.
34. Bialystok E. Global-Local and Trail-Making tasks by monolingual and bilingual children: Beyond inhibi-
tion. Developmental Psychology. 2010; 46: 93–105. https://doi.org/10.1037/a0015466 PMID:
20053009
35. Anderson V. Assessing executive functions in children: Biological, psychological, and developmental
considerations. Neuropsychological Rehabilitation. 1998; 8: 319–349.
36. Maj M, D’Elia L, Satz P, Janssen R, Zaudig M, Uchiyama C, et al. Evaluation of two new ncuropsycholo-
gical tests designed to minimize cultural bias in the assessment of HIV-1 seropositive persons: A WHO
study. Archives of Clinical Neuropsychology. 1993; 8: 123–135. PMID: 14589670
37. Williams J, Rickert V., Hogan J, Zolten AJ, Satz P, D’Elia LF, et al. Children’s Color Trails. Archives of
Clinical Neuropsychology. 1995; 10: 221–223.
38. Tombaugh TN. Trail Making Test A and B: Normative data stratified by age and education. Archives of
Clinical Neuropsychology. 2004; 19: 203–214. https://doi.org/10.1016/S0887-6177(03)00039-8 PMID:
15010086
39. Wechsler D. Wechsler Intelligence Scale for Children: Administration and scoring manual (Australian
Version; 4th Ed). 2003: Pearson Clinical and Talent Assessment: Sydney, Australia.
40. Case R, Kurland DM, Goldberg J. Operational efficiency and the growth of short-term memory span.
Journal of Experimental Child Psychology. 1982; 33: 386–404.
41. Efron B, Tibshirani RJ. An Introduction to the Bootstrap. 1993: Chapman & Hall: New York, NY.
42. Moffitt TE, Arseneault L, Belsky D, Dickson N, Hancox RJ, et al. A gradient of childhood self-control pre-
dicts health, wealth, and public safety. Proceedings of the National Academy of Science. 2011; 108:
2693–2698.