In the clock drawing
test, the subject is presented with a
white paper with the
instructions to draw a clock. There is
no time limit. In the free-drawn method, the subject is asked to draw a clock
from memory. In the pre-drawn method,
the subject is presented with a circular contour and is expected to draw in the
numbers on the clock face. Sometimes the subject is asked to draw the hands at
a fixed time, often 10 past 11, but in many
cases the hands are excluded. In still another
method the subject is asked only to set the hands at a fixed time on a
pre-drawn clock, complete with contour and numbers.
Performance of this test requires verbal understanding
(of the directions), memory and retrieval of information stored visually, and
constructive skills. Error types typically included deficits in the
spatial arrangement of numbers, incorrect sequencing
of numbers, omission or repetition of numbers, perseveration, number rotation
or reversal, incorrect placement of hands to a specified time, and incorrect proportion
of the hour and minute hands.
According to
Watson's method, the subject is instructed to draw numbers within a pre-drawn
circle 10 cm in diameter to make it look like the face of a clock. After
completion, the clock face is divided into quadrants by drawing one line
through the centre of the circle and the number 12 and a second line
perpendicular to the first line. The number of digits in each quadrant is
counted. If a digit falls on the reference line, it is included in the quadrant
that is clockwise to the line. The placing of any three digits in a quadrant is
considered to be correct. An error score of one is assigned for each of the
first three quadrants containing any erroneous number of digits and an error
score of four is assigned for the fourth quadrant if it contains an erroneous
number of digits. Thus a maximum error score of seven can be obtained. The
normal range for the score is 0-3. A score of 4 or greater in this scoring
system has a high sensitivity for
identifying dementia.
The
clock-drawing test is used for screening for cognitive impairment and dementia
and as a measure of spatial dysfunction and neglect. Neglect is a condition
in which, after damage to one hemisphere of the brain is sustained, a deficit
in attention to and awareness of one side of space is observed. It is defined
by the inability of a person to process and perceive stimuli on one side of the
body or environment, where that inability is not due to a lack of sensation. Neglect is usually apparent in the opposite
side to the damaged hemisphere, and it is more common in the left side of the
space (following damage to the right hemisphere).
Adults with neglect tend to draw all numbers in the
right side of the clock. Neglect can be compensated for with a planning
strategy (for example, placing the numbers 12,3,6 and 9 first, and then placing
the other numbers).
Most children aged eight and above can set the hands to
the requested time, while the ability to draw the clock face itself continues
to improve gradually at least up to the age of 12 (Cohen studied this with
children up to the age of twelve, in 2000.
I wonder if it's different nowadays, when children mainly use the
digital watch in their cellular phone).
Cohen
also found that by age 7, the vast majority of children no longer demonstrated
number reversals. By age 8, children no longer neglected quadrants of the clock
face (neglect referring to not placing numbers in an entire quadrant as opposed
to omitting numbers).
For those 6- and 7-year-olds who failed to use a quadrant, the pattern
generally was
of upper
left quadrant neglect as opposed to hemineglect, lower left, or lower right
quadrant neglect;
none of the children neglected the upper right quadrant. This form of apparent "neglect"
results from difficulties in planning and organization related to the lack of
maturity of the frontal lobes in this age, and not from neurological problems.
Cohen found a development in the ability to draw equal intervals between the numbers
from age 6 to 11. This ability is not
fully developed by the age of 12.
Clock face drawing in children with
attention-deficit/
hyperactivity
disorder
Children with ADHD have difficulties with
self regulation, planning and executive functions. Studies found that children with ADHD perform
significantly below average in terms of sequencing and positioning numbers
despite adequate visual–spatial and visual–motor integrative abilities. Qualitatively, planning errors in the
placement of numbers around the clock face were found frequently. Further, when
children were subsequently provided with a predrawn clock that had anchoring
stimuli in place (e.g., the numbers 3, 6, 9, and 12 were predrawn), their clock
construction improved significantly, validating that errors on their original
drawings were due to planning as opposed to visual–spatial deficits.
Forty one children
with ADHD and forty one in a control group participated in Kirby, Cohen and
Hynd's study (reference below). The
children were 5-12 years old and did not take medication during testing. All children did not have learning or
behavior problems. Children with ADHD performed less
well than controls on both clock face construction and setting of the requested
time. It should be noted, however, that
children with ADHD still performed within the low average range on these
measures.
Neglect was defined for
the purposes of this study as the failure to use at least one entire quadrant
of the clock face, with numbers 1–12 typically present but crowded together. None of the children older than 8 years of age
neglected a quadrant. Some degree of left visual–spatial neglect was evident in
children with ADHD through age 8, whereas neglect was present through
age 7 in matched controls. Further, neglect appeared to be specific to the ability
to plan the figure. All children with ADHD who neglected a quadrant failed to
use the top left quadrant, and 67% neglected both left quadrants. All controls
who neglected a quadrant neglected the top left quadrant, with 33% neglecting
both left quadrants. None of the participants neglected quadrants on the right
side.
For both groups,
spacing errors were noted at all ages, but for control children the proportion of errors slowly
decreased as they matured. For example, none of the 6- and 7-year-olds demonstrated
equidistant spacing between numbers, while 27% of 10- and 11-year-olds were able to evenly space
numbers around the clock. In
contrast, all of the children with ADHD continued to demonstrate poor spacing
at ages 10 through 12.
A positive correlation was found between the ability to
draw a clock and measures of executive functions like perseverations and
difficulty maintaining set in the WCST (Wisconsin card sorting test). Visuospatial
perception and grapho-motor skills were not related to ADHD
children's ability to draw a clock, but the Wechsler Block Design test was a
significant predictor of this ability (maybe because it also
requires a certain amount of planning and executive functions).
Clock face drawing in children with dyslexia
Eden, Wood and Stein (reference below)
compared between four groups of fifth grade children:
Children with
dyslexia – 26 children who scored below 85 in the Woodcock-Johnson
Psychoeducational Battery reading standardized score and an average IQ
score in the WISCR.
Children without
dyslexia (ND) – 39 children with Woodcock-Johnson reading
standardized score between 85 and 115.
Their score on the WISC-R was also between 85 and 115.
Garden variety poor
readers – 12 children whose reading scores below 85 on the Woodcock-Johnson and
whose IQ on the WISC-R was also below 85.
Sixteen
miscellaneous children were also included.
They were all typical readers, but they had IQs below 85 or above 115.
To identify the number of children with dyslexia who drew
defective clocks, the authors investigated how many children in each group
performed 2 SD or more below the group
mean (calculated from the ND sample). About eight percet of the no dyslexia group, 46% of the dyslexia group, and 25% of the garden variety
poor reader group performed below this level.
Children with dyslexia tended to draw all the digits on the right side
of the clock compared with the non dyslexia group.
This moderate
neglect of the left side, hints that children with dyslexia may have right
hemisphere damage. These children
usually noticed that their clocks "don't look good" and could tell
why. It can be argued that since a clock
is usually drawn clockwise, it's possible that the clock drawing test causes
bias towards grouping of the numbers to the right side. However the non – dyslexia group showed the
opposite pattern – a slight tendency to group the numbers to the left
side.
There
were no differences between the children with and without dyslexia in clock
size or in the order of the numbers drawn.
The clock drawing test was not correlated with verbal or performance
IQ.
Since some of the children with dyslexia
in this study also had ADD, the researchers tried to see if ADD affected clock
drawing performance. It did not, but
this study did not include a group of children with ADD and without reading
disabilities.
To summarize, these studies do not have
norms for clock drawing. Qualitatively,
it seems that this test is suitable for children aged 12 or older. Children with ADHD perform on this test less well than children without ADHD, but still within normal limits. Their mistakes result from difficulties in
planning and executive functions. Children
with dyslexia also tend to perform less well on this test than children without
dyslexia. They tend to group the numbers
and to draw less numbers in the upper left quadrant of the clock.
Agrell, B., & Dehlin, O. (1998). The clock-drawing test. Age and
Ageing, 27(3).
Kibby, M. Y., Cohen, M. J., & Hynd, G. W. (2002). Clock face drawing in children with attention-deficit/hyperactivity
disorder. Archives of clinical neuropsychology, 17(6), 531-546.
Eden, G. F.,
Wood, F. B., & Stein, J. F. (2003). Clock drawing in
developmental dyslexia. Journal of
Learning Disabilities, 36(3), 216-228.
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