CHAPTER 5 Applications
5.6 Application on Two Persons with Cerebral Palsy
5.6 Application on Two Persons with Cerebral Palsy
Cerebral palsy is a clinical syndrome characterized by movement disorders caused by a non-progressive injury to the immature brain. Computer access for people with severe cerebral palsy is a complicated task. It is not only to support an alternative input device, but should develop an appropriate intervention and training based on the individual’s condition.
5.6.1 Case Study A
5.6.1.1 The Profile of Bob
Bob is a second grade student at a special education high school in Taiwan. He is a 19-year-old adolescent with severe cerebral palsy of athetoid type (which covers 15% ~ 20% of cerebral palsy caused by jaundice, anoxia, and asphyxia that injure the basal ganglia and extra pyramidal tracts of the brain). He has severe impairment with his both hands, and has difficulty in communicating with others due to enormous problem in articulating.
Bob used direct access to the keyboard for text entry and had used the QWERTY
keyboard as his text entry device for five years. Bob used no adaptive devices to access the computer keyboard. He could only use his left foot independently to control the QWERTY keyboard placed on the floor. However, unintentional pressing on keys occurred with this technique. Therefore, it is a difficult task for him to make effective communication through computers. Yet with instructions and help, he is able to type in easy vocabulary for communication.
5.6.1.2 The Intervention of Bob
In the comprehensive evaluation of computer access from Bob, the problems of
Figure 5-6 The comprehensive evaluation for Bob
alternative input device to meet the participant’s needs.
Before the intervention, Bob was assessed on his motor ability with the scale of the computer access assessment (Wu, Meng, Wang, Wu & Li, 2002) to determine on the most appropriate input method and the alternative computer device that best suits the participant’s needs. The result shows that his both hands are not able to access a computer, but his left foot is usable and he had the experience. Additionally, the mouse evaluation program (Chen, Meng, Hsieh, Chu & Li, 2002) was to analyze the utilization of the possible alternative input devices. The comprehensive evaluation is demonstrated in figure 5-6. The participants were required to navigate the mouse cursor to the target and click as correctly and quickly.
As demonstrated in Figure 5-7, an alternative keypad substituted the standard number keypad and used a USB interface. The size of the alternative keypad is 40cm x 20cm. The diameter for each key is 3.2 cm, with 1 cm. interval between two keys.
Figure 5-7 The prototype of customized alternative input device for Bob
To diminish the fatigue caused by the participant, a pulley could be added and the user was able to travel freely. However, the participant prefers the device without pulley.
Result and discussion
The CPM performance of Bob is shown in Figure 5-9. The mean of the QWERTY keyboard in baseline was 8.5 characters per minute. The performance was stable.
Therefore, Bob entered comparison phase after four trials. The CPM performance in the comparison phase improved from 8.7 to 9.9 CPM with practical zero slope (z=.02).
The mean of the first three trails was 9.5 CPM as well as 9.2 CPM for the last tree trails.
Bob generated 6.9 CPM during the first trial of D3 on-screen keyboard only.
However, his performance improved rapidly and at the third trail he achieved the rate of 10.8 CPM on D3 on-screen keyboard, thus his performance assisted by D3
on-screen keyboard exceeding that by QWERTY keyboard. His average performance Figure 5-8The condition of new device intervention for Bob
was 9.88 CPM in the comparison phase. Although the mean of the last three trails
(11.7 CPM) was 1.39 times as fast as the first three trails (8.4 CPM), and the trend
was positive. The trend of the phase was not significant (z=2.04) for D3 on-screen
keyboard. The comparison phase was terminated at session 8 when the performances
of last three trails were not improved continually. The mean of the first three trails
was 88.4% of the QWERTY keyboard; however, the mean of the last three trials was
1.27 times as fast. In the final phase, Bob typed 14.9 CPM on average which was 1.27
times as fast as the mean of the last three trails on the comparison phase.
Figure 5-9 The typing speed of the two text entry systems during the three phases for Bob
As Figure 5-10 indicates, the accuracy for Bob’s QWERTY keyboarding was less
than 90% across the phases and the mean for accuracy was 79.2% during baseline
with no trend. The accuracy for QWERTY keyboarding during the comparison phase
remained less than 90% (mean=83.4%) with stable and insignificant slope change
(Z=-.56). The mean of the first three trials was 86.1% and the last three trails was
81.8%. For D3 on-screen keyboard, the accuracy of the first trial was 92.2% during
the comparison phase. The mean of the first three trails was 91.3% while the last three
trials was 95.3%. The mean of the phase was 93.1%. The variety was stable and the
change of slope was not significant (Z=.51). The accuracy of D3 on-screen keyboard
remained high in the final phase (mean=95.8%).
Figure 5-10 The accuracy of the two text entry systems during the three phases for Bob
The Profile and Intervention of Carl
Carl, diagonsized with cerebral palsy, athetoid type, was 19 years old at the start of
the study. He was a twelfth grade student at a special senior high school in Taiwan. He
has poor head and neck control and limited upper extremity control. Communication
is a problem for him. His teacher encourages him to use computers as expressive
instruments. He cannot hold a pen and employs a keyguard to access the standard
keyboard to do class work (As shown in Figure 5-11). He could only depend on his
right middle finger for most motor control. With over 7 years of computer experience,
he used the computer for education, leisure and communication activities. In the study,
Carl used the number keys on the standard keyboard with a keyguard.
Figure 5-11 Carl used his right middle finger with a keyguard to interact with computer
Result and discussion
The CPM performance of Carl is shown in Figure 5-12. The mean of the QWERTY
keyboard in baseline was 15.3 CPM. The performance slope and trend were both zero.
Carl’s CPM performance improved in the comparison phase, varying from 15.2 to
20.7 CPM with no trend. The mean for the phase was 18.2 CPM. The slope changed
significantly (z=3.25, p<.01). However, the mean for the last three trails (17.4 CPM)
was only 1.08 times as fast as the first three trails (16.1CPM).
Figure 5-12 The typing speed of the two text entry systems during the three phases for Carl
performance improved progressively and at the 17th trial when he achieved the rate of
19.8 CPM on D3 on-screen keyboard, thus exceeding that of the QWERTY keyboard.
The mean of the phase was 16.1 CPM. The mean of the last three trails (21.1 CPM)
was 2.15 times as fast as the first three trails (9.8 CPM). The slope of the phase was
significant (z=4.88, p<.01) for D3 on-screen keyboard. The comparison phase was
terminated at session 28 since the performance of the final three trials did not improve.
The first mean of three trials of D3 on-screen keyboard was only 60.8% of the
QWERTY; however, the mean of last three trials was 1.21 times as fast as the
QWERTY. In the final phase, Bob typed 21.9 CPM on average with no trend.
Figure 5-13 The accuracy of the two text entry systems during the three phases for Carl
Carl’s accuracy using both keyboards was above 90% across the phases. As
Figure 5-13indicates, the mean for accuracy was 96.1% during baseline. The variety
was stable with no visible trend. The accuracy for QWERTY keyboarding during the
comparison phase remained high (mean=95.9%). For D3 on-screen keyboard, the
accuracy of the first trial was 94.5% during the comparison phase. The mean of the
first three trails was 94.2% while the last three trials was 93.4%. The mean of the
phase was 93.5%. The variety was stable with no observed trend (Z=-.26). The
accuracy using D3 on-screen keyboard was maintained in the final phase
(mean=91.3%).