The correlation between sex or use of (non)dominant hand
and the speed-accuracy trade-off
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Faculty of Health, Medicine, and Life Sciences (FHML)
Maastricht University
Course BBS1004
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, Introduction
Fitts’ law states that there is a relationship between the time it takes to move to a target and the
distance and size of the target. To resemble this, a wide range of tasks such as a simple point-select
task that requires participants to tap on two targets on a screen alternately shows the clear
correlations Fitts’ law assumes between the movement time and accuracy trade-off, and the size of
the targets or the distance between the targets (1, 2, 3). The law is defined by the following formula:
MT =a+b∗log 2 ( 2WA )
This equation describes the movement time (MT) as a function of A, amplitude, and W, width. a and
b are the intercept and slope and depend on the specific data. Log to the base two of twice the
amplitude between two targets (A) divided by the target width (W) is called the index of difficulty
(ID). The MT and ID are linearly related according to Fitts’ law (5), and the index of difficulty
expresses how challenging the point-select task is for different combinations of A and W.
Not only the MT plays a major role during such a point-select task, but the accuracy of the performed
movement is also of importance, it is expressed as the variable error (VE). A large VE reflects a larger
spread of the movement endpoints around the target, and therefore a more inaccurate movement.
Several studies on differences in motor skills based on sex have established that women have an
evolutionary advantage and will be more accurate, though slower, when performing fine-motor tasks
(6, 7, 8). This has led to research showing evidence of a speed and accuracy trade-off, in which males
are more likely to prefer speed over accuracy, and females will focus more on accurate movements
while performing them slower (1, 8). Maastricht University arranged this experiment to establish
whether these different movement strategies adopted by men and women will act on these point-
select task results by showing a greater MT amongst female Biomedical Sciences students at
Maastricht University, but a lower VE than male students.
Besides investigating the differences in accuracy based on sex using Fitts’ law test, this study also
aims to establish whether there is an influence of the use of one’s dominant hand on the outcomes
of the Fitts’ law test. To simplify, only the biomedical sciences students whose dominant hand is the
right one participated in this research, and in general, to right-handed people it applies that they are
faster and more accurate with their dominant, right, hand (9, 10). Therefore, the same is expected
for the outcomes of this research, a lower mean VE and MT when the dominant hand is used.
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