Cappelletti, M., Freeman, E.
D., & Butterworth, B. L.
(2011).Time processing in
dyscalculia. Frontiers in psychology, 2.
How do we judge the length of time of events
(without looking at our watch…)? Of events that last a few seconds? We probably
conduct an inner counting of the number of "seconds" the event
lasted. This means that we use numbers
to measure time.
This is obvious when we learn to tell time
(especially with an analogical watch). In
order to be able to tell time we have to master a few arithmetic concepts
("half past four"; "a quarter to nine"; "a quarter
past seven") and to know the "time system" (there are sixty
seconds in a minute, sixty minutes in an hour, 24 hours in a day), that in some
respects is similar to the base 10 number system.
This interesting study looked into aspects of
these phenomena. Twelve dyscalculic
adults and 22 non-dyscalculic adults participated.
It seems to me, that the assigning of
participats to the dyscalculic and non-dyscalculic groups wasn't optimal. This might have, in my opinion, weakened the
results.
How were participants deemed dyscalculic? They had to satisfy four criteria:
·
A score in the Dyscalculia Screener that is one standard
deviation or more below average (more on this test here http://beyondiq.blogspot.co.il/2014/07/dyscalculia-screener-computerized-test.html ). They
did satisfy this criterion.
·
An average IQ score (at least).
They satisfied this criterion as well.
·
A low score in an arithmetic achievement test (GAD, Graded
Difficulty Arithmetic Task). A look at the data reveals that eight of the
twelve dyscalculic participants had a "dull average" score in this
test. A dull average score is not a
score that is significantly below average.
The average score of all twelve participants in this test was dull
average.
·
Deficient functioning in the arithmetic subtest of the
WAIS-R. A look at the data reveals that
out of twelve participants, four scored between 8 and 9 and another had a score
of 7. Since the subtest's average is 10
and the standard deviation is 3, these five participants did not satisfy this
criterion.
The authors write that the 22 participants in
the control group were not given the dyscalculia screener. They don't supply the control group's data on
the three other criteria.
Under these limitations I will consider the
results with caution. The questions that
were asked in this study are interesting in themselves.
The authors first asked the participants
questions about everyday situations involving time estimation or knowledge
about time:
An example of questions that require time
estimation: How much time is needed to make a cup of tea?(they are English…) How much time is needed to fly from London to
New York? (this question is influenced by general information knowledge).
An example of a question that requires exact
calculation: If the time is now 10.35 p.m., what time will it
be in 2 h and 50 min?
An example of a question that requires knowledge about time facts: How many hours are
in a day?
An example of a question that requires time
comparison: What time is the latest:
11:45 or 15:30?
There was no difference between the
dyscalculics and the control group on questions about time estimation, time
comparison and time facts. Dyscalculics performed
significantly worse than controls on questions requiring exact time
calculations.
After this phase, the authors looked into the
influence of numerical stimuli on the perception of time. For this purpose the participants performed
two tasks. I'll refer here to one of
them:
The participants saw the digit 5 projected on a computer screen for a certain
length of time. Then a second digit was projected for a certain length of
time. The second digit could have been 1
or 9. The participants had to decide
whether the second digit was projected for a longer or a shorter period of time
than the first digit.
We already know that children who are not dyscalculic display a
numerical stroop effect. The numerical
stroop task involves making a fast decision about the physical size of digits
(which digit is physically larger?). When
there is congruence between the digits' value and physical size (5 3) performance of typically developing
children is faster than when there is incongruence between the digits' value
and physical size (5 3). This effect does not happen with dyscalculic
children. The reason for that may be
that dyscalculic children don't link numbers with their quantitative value.
The numerical stroop effect indicates that we link quantitative value with physical
size. Do we likewise link between quantitative
value and time perception?
This leads us to the hypothesis that
participants in the control group would think that "1" is projected for a shorter period of
time than "5" was (disregarding the actual situation). That's because the low value of 1 would
affect the subjective perception of time.
We may also hypothesize that participants in
the control group would think that "9" is projected for a
longer period of time than "5" was (disregarding the actual
situation). That's because the higher
value of "9", compared to "5", would affect the subjective
perception of time.
We may also hypothesize that this effect will
not appear with dyscalculic participants.
They will not perceive the digit 1 as projected for a shorter period of
time relative to the digit 5, and will not perceive the digit 9 as projected
for a longer period of time than the digit 5.
That's because dyscalculics don't link digits with their quantitative
value. When digits or numbers are not
linked with their quantitative value, it's hard to take the next step and link
the quantitative value with perceived time length.
The results indeed show
that the perception of time of dyscalculic participants was not affected by the
quantitative value of numbers. The perception
of time of control subjects was affected by the quantitative value of numbers. The control
group participants perceived the number 9 as projected for a longer period of
time than the number 5. They also perceived
the number 1 as projected for a shorter period of time than the number 5, but
as projected for a shorter period of time than the number 9.
The meaning of these
findings may be that we link between quantitative value and subjective time
perception. People with dyscalculia
apparently don’t make such a link. More research is needed
with larger groups and stricter group criteria in order to confirm these
findings.
No comments:
Post a Comment