Dual-Task Performance Involving Hand Dexterity and
Cognitive Tasks and Daily Functioning in People With
Schizophrenia: A Pilot Study
Keh-chung Lin, Yi-fang Wu, I-chen Chen, Pei-luen Tsai, Ching-yi Wu,
Chia-ling Chen
MeSH TERMS
activities of daily living
cognition
hand
psychomotor performance
schizophrenia
task performance and analysis
OBJECTIVE. This study investigated separate and concurrent performance on cognitive and hand dexterity
tasks and the relationship to daily functioning in 16 people with schizophrenia and 16 healthy control
participants.
METHOD. Participants performed the Purdue Pegboard Test and the Serial Seven Subtraction Test under
single- and dual-task conditions and completed two daily functioning evaluations.
RESULTS. The hand dexterity of all participants declined in the dual-task condition, but the discrepancy
between single-task and dual-task hand dexterity was greater in the schizophrenia group than in the control
group (p < .03, d > .70, for all). The extent of discrepancy in hand dexterity was negatively correlated with
daily functioning in the schizophrenia group (rs 5 2.3 to 2.5, ps 5 .04–.26).
CONCLUSION. Ability to perform dual tasks may be an indicator of daily functioning in people with
schizophrenia. Use of dual-task training may be considered as a therapeutic activity with these clients.
Lin, K.-C., Wu, Y.-F., Chen, I.-C., Tsai, P.-L., Wu, C.-Y., & Chen, C.-L. (2015). Dual-task performance involving hand
dexterity and cognitive tasks and daily functioning in people with schizophrenia: A pilot study. American Journal of
Occupational Therapy, 69, 6903250020. http://dx.doi.org/10.5014/ajot.2014.014738
Keh-chung Lin, ScD, is Professor, School of
Occupational Therapy, College of Medicine, National
Taiwan University, Taipei.
Yi-fang Wu, MS, is Occupational Therapist, Department
of Psychiatry, National Taiwan University Hospital, Taipei.
I-chen Chen, MS, is Research Assistant, School of
Occupational Therapy, College of Medicine, National
Taiwan University, Taipei.
Pei-luen Tsai, PhD, is Associate Professor, Department
of Occupational Therapy, College of Medicine, National
Cheng Kung University, Tainan, Taiwan.
Ching-yi Wu, ScD, is Professor and Chair, Department
of Occupational Therapy, College of Medicine, Chang
Gung University, Tao-Yuan County, Taiwan; cywu@mail.
cgu.edu.tw
Chia-ling Chen, PhD, is Professor, Department of
Physical Medicine and Rehabilitation, Chang Gung
Memorial Hospital, Tao-Yuan County, Taiwan.
D
ual tasking is performance of two tasks simultaneously (Kahneman, 1973;
Pashler, 1994). Combinations of hand dexterity tasks and cognitive tasks,
such as speaking on the telephone while writing a message or listening to the
teacher while taking notes in class, are ubiquitous in daily activities. People pay
less attention to each task when the demands of dual tasking exceed their attention capacity (Kahneman, 1973); this decrease in availability of attention for
each task is termed interference. Increased understanding of clients’ concurrent
motor and cognitive task performance is essential for evaluating their daily
functioning (Christofoletti, Andrade, Beinotti, & Borges, 2014; Haggard,
Cockburn, Cock, Fordham, & Wade, 2000).
Studies of dual-task performance in people with schizophrenia have suggested
that they experience more difficulties with concurrent cognitive and perceptual tasks
and concurrent motor tasks than healthy control participants (Fuller & Jahanshahi,
1999; Granholm, Asarnow, & Marder, 1996; Schwartz et al., 1989, 1991). Only
one study has explored performance of a concurrent motor and cognitive task in
people with schizophrenia (Lallart et al., 2014). Participants were required to count
forward, count backward, and speak animal names spontaneously (verbal fluency)
while walking. The participants with schizophrenia showed poorer walking performance than the healthy control participants because the cognitive tasks caused
greater interference under the dual-task condition (Lallart et al., 2014).
Like walking capacity, hand dexterity is critical in daily functioning, and
impaired hand dexterity has been correlated with compromised daily functioning
The American Journal of Occupational Therapy
Downloaded From: http://ajot.aota.org/ on 03/03/2016 Terms of Use: http://AOTA.org/terms
6903250020p1
in people with schizophrenia (Green, Kern, Braff, & Mintz,
2000; Lehoux et al., 2003; Midorikawa et al., 2008;
Sasayama et al., 2014). However, no studies to date have
considered hand dexterity when investigating dual-task
performance in people with schizophrenia. In addition,
deterioration in performance of dual tasks associated with
poor daily functional performance was reported in a study
of people with neurological deficits such as brain injury and
stroke (Haggard et al., 2000). Nevertheless, no studies have
yet investigated the relationship between daily activities and
dual-task performance in people with schizophrenia.
This study had two objectives: (1) to compare hand
dexterity in single-task and dual-task conditions in participants with schizophrenia with that of healthy control participants and (2) to examine the relationship between
discrepancy in hand dexterity between conditions and daily
functioning in the participants with schizophrenia. We hypothesized that in the dual-task condition hand dexterity
would decline significantly more in the participants with
schizophrenia than in the control participants and that daily
functional performance would be negatively correlated with
discrepancy in hand dexterity between conditions in participants with schizophrenia such that the smaller their discrepancy in hand dexterity, the better their daily functioning.
Method
The protocol for this study received ethical approval from
the National Taiwan University Hospital’s institutional
review board.
Participants
Occupational therapists recruited 16 patients with schizophrenia being treated at a psychiatric clinic and day care
rehabilitation center at the National Taiwan University
Hospital. Inclusion criteria were diagnosis of schizophrenia
by a psychiatric clinician according to World Health
Organization (2010) diagnostic criteria, age of 20–65 yr,
stable status with no change in antipsychotic medications in the previous 3 mo, adequate cognitive abilities
reflected in scores on the Mini-Mental State Examination
(MMSE) >24 (Folstein, Folstein, & McHugh, 1975; Heun,
Papassotiropoulos, & Jennssen, 1998), and signed informed
consent. The control group consisted of 16 healthy, ageand gender-matched volunteers. Exclusion criteria were
presence of another neurological or psychiatric diagnosis
and MMSE score of £24.
Measures
Purdue Pegboard Test. The Purdue Pegboard Test
(PPT; Tiffin & Asher, 1948) measures hand dexterity.
Although the test comprises four subtests, we used only
three: placing small metal rods into holes in a pegboard (1)
with the preferred hand, (2) with the nonpreferred hand,
and (3) with both hands. (The fourth subtest involves
assembly and measures not only dexterity but constructional praxis, so we chose not to use it.) The sequence of
subtests was determined randomly by drawing lots. The
participants were instructed to place the rods individually
into holes as quickly and correctly as possible, and the
number of rods placed in the pegboard in 30 s was recorded. All participants completed two trials for each
subtest in the single- and dual-task conditions, and the
averages of each pair of trials were used in the analysis.
The reliability of the PPT ranges from .60 to .91 and
the validity from .07 to .76 (Tiffin & Asher, 1948). The
test–retest reliabilities of the subtests are moderate to
good in people with schizophrenia (intraclass correlation
coefficient [ICC] 5 .73–.88; Lee et al., 2013).
Serial Sevens Subtraction Test. We chose the Serial
Sevens Subtraction Test (SSST; Manning, 1982) as
a cognitive task for the dual-task condition. All participants were instructed to subtract 7 from the beginning
number and then to subtract 7 from each successive
answer as quickly and correctly as possible. Clinicians
commonly administer the SSST starting from 100 to
examine cognitive ability; to avoid a learning effect, we
started with a random number between 290 and 300
(Proud & Morris, 2010). Participants completed two
trials in both the single- and dual-task conditions, and the
average number of correct responses in each pair of trials
was used in the analysis (Manning, 1982; Proud &
Morris, 2010; Smith, 1967).
University of California, San Diego, Performance-Based
Skills Assessment–Brief Version. The University of Cal-
ifornia, San Diego, Performance-Based Skills Assessment–
Brief Version (UPSA–B; Patterson, 2010) is designed to
directly assess functional capacity. This performancebased test contains communication and financial domains. The communication domain uses an unplugged
telephone in a series of role-play situations, including
making emergency calls, calling directory assistance to
request a telephone number, and rescheduling a medical
appointment. The financial domain involves counting
out given amounts and reading, filling out, and using
a check. Higher scores indicate better functional capacity
(Mausbach et al., 2011).
Test–retest reliabilities of the UPSA–B ranged from
r 5 .66 to r 5 .81 over follow-up periods of up to 36 mo
in people with schizophrenia (Leifker, Patterson, Bowie,
Mausbach, & Harvey, 2010). The UPSA–B has adequate
psychometric properties, predicts residential independence, is
6903250020p2
Downloaded From: http://ajot.aota.org/ on 03/03/2016 Terms of Use: http://AOTA.org/terms
May/June 2015, Volume 69, Number 3
sensitive to change, and requires only 10 to 15 min to administer (Mausbach, Harvey, Goldman, Jeste, & Patterson,
2007).
Activities of Daily Living Rating Scale–III. The Activities
of Daily Living Rating Scale–III (ADLRS–III; Chu,
2004) is a self-administered scale that assesses daily
functioning in people with schizophrenia. Items address
10 topics: independence, hygiene, leisure, graphics, news,
words, finance, traffic, communication, and adaptation.
Included are self-reported questions (e.g., Could you go
out for shopping?), questions of general knowledge with
standard answers (e.g., Who is the president now?), and approaches to problem solving (e.g., When you are in a bad
mood, what do you do?). Each item is scored from 0 to 10,
with a maximum total score of 100, and higher scores indicate
better functional abilities (Chu, 2004; Chu & Hsieh, 2004).
The ADLRS–III has demonstrated good test–retest reliability
(ICC 5 .87, p < .001), convergent validity, and discriminant
validity in psychiatric patients (Chu & Hsieh, 2004).
Procedures
Participants were individually evaluated in two sessions and
performed the tests in the same sequence. For the singletask condition, participants completed the ADLRS–III,
then the UPSA–B, then the SSST, and finally the PPT.
For the dual-task condition, participants were instructed to
complete the SSST and PPT simultaneously and as
quickly and correctly as possible.
Statistical Analysis
We used IBM SPSS Statistics Version 19.0 (IBM Corporation, Armonk, NY) to analyze study data. De2
mographic data were analyzed using t tests and x . We
used the t test to examine change in hand dexterity by
comparing the PPT scores under the dual-task versus the
single-task condition as follows: discrepancy in dexterity 5
[number of pegs under single-task condition 2 number of
pegs under dual-task condition] · 100/[number of pegs
under single-task condition] (Lin, Cermak, Kinsbourne, &
Trombly, 1996). We also used two-way mixed analysis of
variance (ANOVA) with one between-subjects factor
(Group: participants with schizophrenia vs. healthy control
participants) and one within-subjects factor (Condition:
single task vs. dual task) to analyze differences between the
two groups in two conditions. We used Spearman correlation analysis to investigate the relationship between discrepancy in hand dexterity and daily functioning in the
group with schizophrenia. The significance level was set at
.05, and effect size, Cohen’s d, and partial h2 were used to
estimate the magnitude of the effects.
Results
Participants
Demographic and clinical characteristics of the 16 participants with schizophrenia and 16 healthy control participants are summarized in Table 1. The schizophrenia
group had significantly lower educational levels and
MMSE scores than the control group.
Purdue Pegboard Test
Both groups placed fewer pegs in the dual-task condition than
in the single-task condition when using the preferred and the
nonpreferred hand (Figure 1). Significant differences in hand
dexterity were found under the dual-task versus single-task
condition between the two groups for the preferred, the
nonpreferred, and both hands (p < .03, d > .7 for all; Table 2).
Two-way mixed ANOVAs showed a significant interaction
effect for both hands (p 5 .02, h2p 5 .17), a marginal interaction effect for the nonpreferred hand (p 5 .06, h2p 5 .11),
and a moderate interaction effect for the preferred hand (p 5
.19, h2p 5 .06). Significant Condition and Group effects were
documented for preferred, nonpreferred, and both hands (p <
.001, h2p > .52 for all; Table 2). The performance of the
participants with schizophrenia declined considerably from the
single-task to the dual-task condition, and the participants with
schizophrenia placed fewer pegs than the control participants.
Relationship Between Discrepancy in Hand Dexterity
and Daily Functioning in Participants With Schizophrenia
Negative correlations were found between discrepancy in
hand dexterity from the single- to the dual-task condition
and daily functional performance in the schizophrenia
group (Table 3). Only one correlation, between discrepancy in dexterity for both hands and ADLRS–III
scores, was significant (r 5 2.50, p 5 .047). Although
the other correlations were not significant, the effect sizes
were medium to high (r > 2.30, p > .05; Table 3).
Table 1. Participants’ Demographic and Clinical Characteristics
Characteristic
Age, yr
Gender, n
Schizophrenia Control Group
Group (n 5 16),
(n 5 16),
Mean (SD)
Mean (SD)
35.63 (7.80)
35.63 (7.80)
Male
8
8
Female
8
8
13.13 (2.53)
17.06 (1.48)
Education level, yr
2
t or x
p
t (30) 5 0.00 1.00
x2(1) < .00
1.00
t (30) 5 5.38 <.001
Preferred hand, n
Left
Right
MMSE score
2
3
14
13
x (1) 5 .24
.63
29.63 (1.09)
t (30) 5 2.12
.04
28.63 (1.54)
2
Note. MMSE 5 Mini-Mental State Examination; SD 5 standard deviation.
The American Journal of Occupational Therapy
Downloaded From: http://ajot.aota.org/ on 03/03/2016 Terms of Use: http://AOTA.org/terms
6903250020p3
Figure 1. Number of pegs placed under single- and dual-task
conditions in two groups, (A) by preferred hand, (B) by nonpreferred hand, and (C) by both hands.
Note. Error bars indicate standard deviations.
Discussion
To our knowledge, this is the first study to investigate performance in concurrent hand dexterity and cognitive tasks in
people with schizophrenia. Adding a cognitive task interfered
with hand dexterity to a greater extent in the schizophrenia
group than in the control group. This finding is consistent
with studies indicating that cognitive interference with
motor function is greater in people with schizophrenia
(Lallart et al., 2014), in older people with mild cognitive
impairment (Montero-Odasso et al., 2009), and in people with Parkinson’s disease (Fuller et al., 2013; Proud &
Morris, 2010).
The fact that all participants in our study displayed better
hand dexterity under the single-task than the dual-task condition when using the preferred and nonpreferred hand
provides evidence for the capacity model of attention, which
indicates that people have lower capacity for mental work when
performing dual tasks and that implementing incompatible
tasks interferes with the performance of both (Kahneman,
1973; Pashler, Johnston, & Ruthruff, 2001; Ruthruff,
Pashler, & Klaassen, 2001). In our study, participants
performing the PPT (dexterity) and the SSST (cognition)
at the same time experienced similar dual-task interference.
Moreover, the schizophrenia group exhibited significantly worse hand dexterity under the dual-task condition
than did the control group. The effort participants with
schizophrenia required to perform the dexterity tasks rose
gradually when they changed from the preferred hand to
both hands, but for the control group the discrepancy in
dexterity decreased gradually as they moved from the preferred hand to the nonpreferred hand and then both hands.
These findings imply that the healthy control participants
could modulate and allocate attentional effort better to meet
the activity demands and complete tasks. For the participants
with schizophrenia, however, limited attentional resources
may have combined with cognitive deficits to result in poor
attentional modulation and performance. The other plausible explanation is that because the dorsolateral prefrontal
cortex is involved in dual-task conditions (D’Esposito et al.,
1995; Hartley, Jonides, & Sylvester, 2011; Tachibana et al.,
2012), deficits in the dorsolateral prefrontal cortex in the
participants with schizophrenia may have resulted in their
poor performance in the dual tasks (Behere, 2013; Chen
et al., 2014; Palaniyappan, Park, Balain, Dangi, & Liddle,
in press; Rubinov & Bullmore, 2013).
In addition, discrepancy in hand dexterity was negatively
associated with daily functional performance in the schizophrenia group. That is, the smaller the decrease in hand
dexterity performance from the single- to the dual-task
condition was, the better the participant’s daily functional
performance was. This negative correlation may indicate that
people with schizophrenia whose hand dexterity decreases
more when they perform dual tasks will exhibit worse daily
functional performance. Although only one negative correlation was significant (i.e., dexterity for both hands and
ALRS–III scores), the effect sizes of all correlations were
medium to large. A similar result was found in a study that
revealed a negative correlation between gait performance and
6903250020p4
Downloaded From: http://ajot.aota.org/ on 03/03/2016 Terms of Use: http://AOTA.org/terms
May/June 2015, Volume 69, Number 3
Table 2. Participant Performance on the Purdue Pegboard Test
Variable
Schizophrenia
Control Group
Group
(n 5 16),
(n 5 16), M (SD)
M (SD)
t (30)
Condition · Group
Effect
t Test
p
d
Condition Effect
Partial h2
p
Partial h2
105.94 <.001
.78
45.27
<.001
.60
.11
69.54 <.001
.70
36.89
<.001
.55
.17
33.49 <.001
.53
47.59
<.001
.61
p
Partial h2
1.79
.19
.06
3.76
.06
6.15
.02
F
(1, 30)
Group Effect
F
(1, 30)
F
(1, 30)
p
Preferred hand
Single, no. of pegs
Dual, no. of pegs
Discrepancy, %
Nonpreferred hand
14.47 (1.70)
9.03 (2.58)
18.06 (1.55)
13.8
(2.77)
37.17 (17.62)
23.18 (13.63)
13.22 (3.33)
17.06 (1.97)
8.25 (2.67)
13.97 (2.28)
34.30 (22.04)
18.26 (8.62)
Single, no. of pegs
20.53 (3.63)
27.16 (3.26)
Dual, no. of pegs
14.44 (4.90)
27.72 (4.20)
Discrepancy, %
29.20 (20.16)
8.63 (13.93)
Single, no. of pegs
Dual, no. of pegs
Discrepancy, %
2.51 .02
2.71 .01
0.89
0.96
Both hands
3.36 .002 0.78
Note. M 5 mean, SD 5 standard deviation.
scores on the Barthel Activities of Daily Living Index (Novak,
Johnson, & Greenwood, 1996) in a dual-task condition
(Haggard et al., 2000).
When performing activities of daily living, people often
must do more than one task at a time. People with schizophrenia may experience dual-task interference that results in
difficulties dealing with the hand dexterity and cognitive
demands of daily functional activities. It follows that dual-task
training that includes hand dexterity and cognitive activities may
help people with schizophrenia improve their daily functioning.
Limitations and Future Research
Our study has several limitations. First, we used convenience
sampling, and our sample size was relatively small. All
participants in the schizophrenia group were from one
hospital, and the healthy control group consisted of volunteers. The small sample size limits the power of our
analysis and the generalizability of the results. The study
used a controllable experimental task, so it is unknown
whether the findings can be transferred to real-life situations.
Second, although we matched our participants with
schizophrenia by age and gender with healthy control participants, the educational levels of the two groups were significantly different; the early onset of symptoms in the
schizophrenia group likely interfered with their educational
attainment. Future studies should match the educational levels
of the experimental group with those of the control group.
Third, all participants with schizophrenia received
antipsychotic treatment during the study, which might have
influenced their cognition and motor function. Therefore,
the test results should be interpreted with caution.
Several issues need further investigation. First, replication of this study with a larger population and probability
sampling is recommended to verify our preliminary findings. Second, according to the capacity model of attention,
the degree of difficulty of a cognitive task may influence
performance, so it would be worth investigating whether
decreasing the degree of difficulty of the cognitive task would
promote dual-task performance. Third, future research
could investigate whether providing participants with
feedback, such as whether they perform each element of the
cognitive task correctly, might facilitate their dual-task
performance. Finally, serial observations could be done to
compare performance in varied conditions within one group
of people with schizophrenia. Doing so could reduce overall
variability and remove participant differences to make the
error components independent from condition to condition.
Implications for Occupational
Therapy Practice
Our findings have the following implications for occupational therapy practice:
• Dual-task performance can be considered a behavioral
marker to assist in designing intervention programs to
address daily functional performance in people with
Table 3. Correlation Between Daily Functioning and Discrepancy
in Hand Dexterity Under Dual-Task Versus Single-Task
Conditions in Participants With Schizophrenia (n 5 16)
Preferred Hand
Measure
r
p
Nonpreferred
Hand
r
p
Both Hands
r
p
ADLRS–III
2.30
.260
2.46
.080
2.50
.047
UPSA–B
2.31
.250
2.45
.100
2.37
.160
Note. ADLRS–III 5 total scores on the Activities of Daily Living Rating Scale–
III; UPSA–B 5 total scores on the University of California, San Diego, PerformanceBased Skills Assessment–Brief Version.
The American Journal of Occupational Therapy
Downloaded From: http://ajot.aota.org/ on 03/03/2016 Terms of Use: http://AOTA.org/terms
6903250020p5
schizophrenia (e.g., work hardening programs, maintenance
functions within the areas of self-care and productivity).
• To improve or avoid deterioration in hand dexterity,
occupational therapy practitioners can simplify tasks
and contexts for people with schizophrenia.
• Practitioners can consider using dual tasks as a therapeutic activity for people with schizophrenia; improvements in hand dexterity in a dual-task situation might
promote ADL function.
Conclusion
This study is the first to examine the effects of performing
a dual task (a manual plus a cognitive task) on hand
dexterity in people with schizophrenia. Participants with
schizophrenia had poorer hand dexterity than healthy
control participants when engaging in dual tasks, and the
amount of discrepancy in hand dexterity between the dualtask and single-task conditions was associated with daily
functioning. Occupational therapy practitioners providing
treatment for people with schizophrenia might consider
using dual tasks as a therapeutic activity. Future research
with larger probability sampling and cognitive activities of
varying difficulties is warranted to validate the findings. s
Acknowledgments
This study was supported in part by the National Health
Research Institutes (NHRI-EX104-10403PI), the Ministry
of Science and Technology (102-2314-B-002-154-MY2,
102-2628-B-182-005-MY3, and 103-2314-B-182-004MY3), the Healthy Aging Research Center at Chang Gung
University (EMRPD1E1711), and the Chang Gung Memorial Hospital (CMRPD 1C0402) in Taiwan.
References
Behere, R. V. (2013). Dorsolateral prefrontal lobe volume and
neurological soft signs as predictors of clinical social and
functional outcome in schizophrenia: A longitudinal
study. Indian Journal of Psychiatry, 66, 111–116. http://
dx.doi.org/10.4103-0019-5545.111445
Chen, C.-M. A., Stanford, A. D., Mao, X., Abi-Dargham, A.,
Shungu, D. C., Lisanby, S. H., . . . Kegeles, L. S. (2014).
GABA level, gamma oscillation, and working memory performance in schizophrenia. NeuroImage: Clinical, 4, 531–539.
http://dx.doi.org/10.1016/10.1016/j.nicl.2014.03.007
Christofoletti, G., Andrade, L. P., Beinotti, F., & Borges, G.
(2014). Cognition and dual-task performance in older
adults with Parkinson’s and Alzheimer’s disease. International Journal of General Medicine, 7, 383–388. http://dx.
doi.org/10.2147/IJGM.S65803
Chu, T.-F. (2004). Manual for the Activities of Daily Living
Rating Scale III. New Taipei City, Taiwan: Hua-jian.
Chu, T.-F., & Hsieh, C.-L. (2004). Reliability and validity of
the Activities of Daily Living Rating Scale III for psychiatric patients: A preliminary study. Journal of Taiwan Occupational Therapy Association, 24, 1–14.
D’Esposito, M., Detre, J. A., Alsop, D. C., Shin, R. K., Atlas,
S., & Grossman, M. (1995). The neural basis of the central executive system of working memory. Nature, 378,
279–281. http://dx.doi.org/10.1038/378279a0
Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975).
“Mini-Mental State”: A practical method for grading the
cognitive state of patients for the clinician. Journal of Psychiatric Research, 12, 189–198. http://dx.doi.org/10.1016/
0022-3956(75)90026-6
Fuller, R., & Jahanshahi, M. (1999). Concurrent performance of motor tasks and processing capacity in patients
with schizophrenia. Journal of Neurology, Neurosurgery,
and Psychiatry, 66, 668–671. http://dx.doi.org/10.1136/
jnnp.66.5.668
Fuller, R. L., Van Winkle, E. P., Anderson, K. E., GruberBaldini, A. L., Hill, T., Zampieri, C., . . . Shulman, L. M.
(2013). Dual task performance in Parkinson’s disease: A
sensitive predictor of impairment and disability. Parkinsonism and Related Disorders, 19, 325–328. http://dx.doi.
org/10.1016/j.parkreldis.2012.11.011
Granholm, E., Asarnow, R. F., & Marder, S. R. (1996). Dual-task
performance operating characteristics, resource limitations,
and automatic processing in schizophrenia. Neuropsychology,
10, 11–21. http://dx.doi.org/10.1037/0894-4105.10.1.11
Green, M. F., Kern, R. S., Braff, D. B., & Mintz, J. (2000).
Neurocognitive deficits and functional outcome in schizophrenia: Are we measuring the “right stuff”? Schizophrenia
Bulletin, 26, 119–136.
Haggard, P., Cockburn, J., Cock, J., Fordham, C., & Wade,
D. (2000). Interference between gait and cognitive tasks in
a rehabilitating neurological population. Journal of Neurology, Neurosurgery, and Psychiatry, 69, 479–486. http://
dx.doi.org/10.1136/jnnp.69.4.479
Hartley, A. A., Jonides, J., & Sylvester, C. Y. (2011). Dual-task
processing in younger and older adults: Similarities and
differences revealed by fMRI. Brain and Cognition, 75,
281–291. http://dx.doi.org/10.1016/j.bandc.2011.01.004
Heun, R., Papassotiropoulos, A., & Jennssen, F. (1998). The
validity of psychometric instruments for detection of dementia in the elderly general population. International
Journal of Geriatric Psychiatry, 13, 368–380. http://dx.
doi.org/10.1002/(SICI)1099-1166(199806)13:6<368::
AID-GPS775>3.0.CO;2-9
Kahneman, D. (1973). Attention and effort. Englewood Cliffs,
NJ: Prentice-Hall.
Lallart, E., Jouvent, R., Herrmann, F. R., Perez-Diaz, F., Lallart,
X., Beauchet, O., & Allali, G. (2014). Gait control and
executive dysfunction in early schizophrenia. Journal of
Neural Transmission, 121, 443–450. http://dx.doi.org/
10.1007/s00702-013-1111-0
Lee, P., Liu, C.-H., Fan, C.-W., Lu, C.-P., Lu, W.-S., &
Hsieh, C.-L. (2013). The test–retest reliability and the
minimal detectable change of the Purdue Pegboard Test
in schizophrenia. Journal of the Formosan Association, 112,
332–337. http://dx.doi.org/10.1016/j.jfma.2012.02.023
6903250020p6
Downloaded From: http://ajot.aota.org/ on 03/03/2016 Terms of Use: http://AOTA.org/terms
May/June 2015, Volume 69, Number 3
Lehoux, C., Everett, J., Laplante, L., Émond, C., Trépanier, J.,
Brassard, A., . . . Roy, M.-A. (2003). Fine motor dexterity
is correlated to social functioning in schizophrenia. Schizophrenia Research, 62, 269–273. http://dx.doi.org/10.1016/
S0920-9964(02)00327-4
Leifker, F. R., Patterson, T. L., Bowie, C. R., Mausbach, B. T., &
Harvey, P. D. (2010). Psychometric properties of performancebased measurements of functional capacity: Test–retest reliability, practice effects, and potential sensitivity to change.
Schizophrenia Research, 119, 246–252. http://dx.doi.org/
10.1016/j.schres.2010.03.021
Lin, K.-C., Cermak, S. A., Kinsbourne, M., & Trombly, C. A.
(1996). Effects of left-sided movements on line bisection
in unilateral neglect. Journal of the International Neuropsychological Society, 2, 404–411. http://dx.doi.org/10.1017/
S135561770000148X
Manning, R. T. (1982). The Serial Sevens Test. Archives of
Internal Medicine, 142, 1192. http://dx.doi.org/10.1001/
archinte.1982.00340190148022
Mausbach, B. T., Depp, C. A., Bowie, C. R., Harvey,
P. D., McGrath, J. A., Thronquist, M. H., . . . Patterson,
T. L. (2011). Sensitivity and specificity of the UCSD
Performance-Based Skills Assessment (UPSA–B) for identifying functional milestones in schizophrenia. Schizophrenia, 132, 165–170. http://dx.doi.org/10.1016/j.
schres.2011.07.022.
Mausbach, B. T., Harvey, P. D., Goldman, S. R., Jeste, D. V.,
& Patterson, T. L. (2007). Development of a brief scale of
everyday functioning in persons with serious mental illness. Schizophrenia Bulletin, 33, 1364–1372. http://dx.
doi.org/10.1093/schbul/sbm014
Midorikawa, A., Hashimoto, R., Noguchi, H., Saitoh, O.,
Kunugi, H., & Nakamura, K. (2008). Impairment of motor dexterity in schizophrenia assessed by a novel finger
movement test. Psychiatry Research, 159, 281–289. http://
dx.doi.org/10.1016/j.psychres.2007.04.004
Montero-Odasso, M., Casas, A., Hansen, K. T., Bilski, P.,
Gutmanis, I., Wells, J. L., & Borrie, M. J. (2009). Quantitative gait analysis under dual-task in older people with
mild cognitive impairment: A reliability study. Journal of
Neuroengineering and Rehabilitation, 6, 35. http://dx.doi.
org/10.1186/1743-0003-6-35
Novak, S., Johnson, J., & Greenwood, R. (1996). Barthel
revisited: Making guidelines work. Clinical Rehabilitation, 10,
128–134. http://dx.doi.org/10.1177/026921559601000208
Palaniyappan, L., Park, B., Balain, V., Dangi, R., & Liddle, P.
(in press). Abnormalities in structural covariance of cortical gyrification in schizophrenia. Brain Structure and Function. http://dx.doi.org/10.1007/s00429-014-0772-2
Pashler, H. (1994). Dual-task interference in simple tasks:
Data and theory. Psychological Bulletin, 116, 220–244.
http://dx.doi.org/10.1037/0033-2909.116.2.220
Pashler, H., Johnston, J. C., & Ruthruff, E. (2001). Attention
and performance. Annual Review of Psychology, 52, 629–651.
http://dx.doi.org/10.1146/annurev.psych.52.1.629
Patterson, T. L. (2010). The UCSD Performance-Based Skills
Assessment (UPSA–BRIEF). La Jolla, CA: Author. Retrieved
from http://www.psychiatrist.com/education/Documents/
UPSA_Brief_Manual.pdf
Proud, E. L., & Morris, M. E. (2010). Skilled hand dexterity
in Parkinson’s disease: Effects of adding a concurrent task.
Archives of Physical Medicine and Rehabilitation, 91, 794–
799. http://dx.doi.org/10.1016/j.apmr.2010.01.008
Rubinov, M., & Bullmore, E. (2013). Schizophrenia and abnormal brain network hubs. Dialogues in Clinical Neuroscience, 15, 339–349.
Ruthruff, E., Pashler, H. E., & Klaassen, A. (2001). Processing
bottlenecks in dual-task performance: Structural limitation
or strategic postponement? Psychonomic Bulletin and Review, 8, 73–80. http://dx.doi.org/10.3758/BF03196141
Sasayama, D., Hori, H., Teraishi, T., Hattori, K., Ota, M.,
Matsuo, J., . . . Kunugi, H. (2014). Benzodiazepines,
benzodiazepine-like drugs, and typical antipsychotics impair manual dexterity in patients with schizophrenia. Journal of Psychiatric Research, 49, 37–42. http://dx.doi.org/
10.16/j.jpsychires.2013.10.019
Schwartz, F., Carr, A. C., Munich, R. L., Glauber, S., Lesser,
B., & Murray, J. (1989). Reaction time impairment in
schizophrenia and affective illness: The role of attention.
Biological Psychiatry, 25, 540–548. http://dx.doi.org/10.1016/
0006-3223(89)90214-X
Schwartz, F., Munich, R. L., Carr, A., Bartuch, E., Lesser, B.,
Rescigno, D., & Viegener, B. (1991). Negative symptoms
and reaction time in schizophrenia. Journal of Psychiatric
Research, 25, 131–140. http://dx.doi.org/10.1016/00223956(91)90006-V.
Smith, A. (1967). The Serial Sevens Subtraction Test. Archives of
Neurology, 17, 78–80. http://dx.doi.org/10.1001/archneur.
1967.00470250082008
Tachibana, A., Noah, J. A., Bronner, S., Ono, Y., Hirano, Y.,
Niwa, M., . . . Onozuka, M. (2012). Activation of dorsolateral prefrontal cortex in a dual neuropsychological
screening test: An fMRI approach. Behavioral and Brain
Functions, 8, 26. http://dx.doi.org/10.1186/1744-9081-8-26
Tiffin, J., & Asher, E. J. (1948). The Purdue Pegboard: Norms
and studies of reliability and validity. Journal of Applied
Physiology, 32, 234–247.
World Health Organization. (2010). International statistical classification of diseases and related health problems (10th rev.).
Geneva: Author.
The American Journal of Occupational Therapy
Downloaded From: http://ajot.aota.org/ on 03/03/2016 Terms of Use: http://AOTA.org/terms
6903250020p7