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Research Article
Issue Date: May/June 2015
Published Online: April 08, 2015
Updated: April 30, 2020
Dual-Task Performance Involving Hand Dexterity and Cognitive Tasks and Daily Functioning in People With Schizophrenia: A Pilot Study
Author Affiliations
  • 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
Article Information
Mental Health / Mental Health
Research Article   |   April 08, 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, April 2015, Vol. 69, 6903250020. https://doi.org/10.5014/ajot.2014.014738
American Journal of Occupational Therapy, April 2015, Vol. 69, 6903250020. https://doi.org/10.5014/ajot.2014.014738
Abstract

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 = −.3 to −.5, ps = .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.

Dual 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 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, age- and 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] = .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 California, San Diego, Performance-Based Skills Assessment–Brief Version (UPSA–B; Patterson, 2010) is designed to directly assess functional capacity. This performance-based 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 = .66 to r = .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 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 = .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 single-task 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. Demographic data were analyzed using t tests and χ2. 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 = [number of pegs under single-task condition − 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 η2 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.
Table 1.
Participants’ Demographic and Clinical Characteristics
Participants’ Demographic and Clinical Characteristics×
CharacteristicSchizophrenia Group (n = 16), Mean (SD)Control Group (n = 16), Mean (SD)t or χ2p
Age, yr35.63 (7.80)35.63 (7.80)t (30) = 0.001.00
Gender, n
 Male88χ2(1) < .001.00
 Female88
Education level, yr13.13 (2.53)17.06 (1.48)t (30) = 5.38<.001
Preferred hand, n
 Left23χ2(1) = .24.63
 Right1413
MMSE score28.63 (1.54)29.63 (1.09)t (30) = 2.12.04
Table Footer NoteNote. MMSE = Mini-Mental State Examination; SD = standard deviation.
Note. MMSE = Mini-Mental State Examination; SD = standard deviation.×
Table 1.
Participants’ Demographic and Clinical Characteristics
Participants’ Demographic and Clinical Characteristics×
CharacteristicSchizophrenia Group (n = 16), Mean (SD)Control Group (n = 16), Mean (SD)t or χ2p
Age, yr35.63 (7.80)35.63 (7.80)t (30) = 0.001.00
Gender, n
 Male88χ2(1) < .001.00
 Female88
Education level, yr13.13 (2.53)17.06 (1.48)t (30) = 5.38<.001
Preferred hand, n
 Left23χ2(1) = .24.63
 Right1413
MMSE score28.63 (1.54)29.63 (1.09)t (30) = 2.12.04
Table Footer NoteNote. MMSE = Mini-Mental State Examination; SD = standard deviation.
Note. MMSE = Mini-Mental State Examination; SD = standard deviation.×
×
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 = .02, ηp2 = .17), a marginal interaction effect for the nonpreferred hand (p = .06, ηp2 = .11), and a moderate interaction effect for the preferred hand (p = .19, ηp2 = .06). Significant Condition and Group effects were documented for preferred, nonpreferred, and both hands (p < .001, ηp2 > .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.
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.
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.
×
Table 2.
Participant Performance on the Purdue Pegboard Test
Participant Performance on the Purdue Pegboard Test×
VariableSchizophrenia Group (n = 16), M (SD)Control Group (n = 16), M (SD)t TestCondition × Group EffectCondition EffectGroup Effect
t (30)pdF (1, 30)pPartial η2F (1, 30)pPartial η2F (1, 30)pPartial η2
Preferred hand
 Single, no. of pegs14.47 (1.70)18.06 (1.55)1.79.19.06105.94<.001.7845.27<.001.60
 Dual, no. of pegs9.03 (2.58)13.8 (2.77)
 Discrepancy, %37.17 (17.62)23.18 (13.63)2.51.020.89
Nonpreferred hand
 Single, no. of pegs13.22 (3.33)17.06 (1.97)3.76.06.1169.54<.001.7036.89<.001.55
 Dual, no. of pegs8.25 (2.67)13.97 (2.28)
 Discrepancy, %34.30 (22.04)18.26 (8.62)2.71.010.96
Both hands
 Single, no. of pegs20.53 (3.63)27.16 (3.26)6.15.02.1733.49<.001.5347.59<.001.61
 Dual, no. of pegs14.44 (4.90)27.72 (4.20)
 Discrepancy, %29.20 (20.16)8.63 (13.93)3.36.0020.78
Table Footer NoteNote. M = mean, SD = standard deviation.
Note. M = mean, SD = standard deviation.×
Table 2.
Participant Performance on the Purdue Pegboard Test
Participant Performance on the Purdue Pegboard Test×
VariableSchizophrenia Group (n = 16), M (SD)Control Group (n = 16), M (SD)t TestCondition × Group EffectCondition EffectGroup Effect
t (30)pdF (1, 30)pPartial η2F (1, 30)pPartial η2F (1, 30)pPartial η2
Preferred hand
 Single, no. of pegs14.47 (1.70)18.06 (1.55)1.79.19.06105.94<.001.7845.27<.001.60
 Dual, no. of pegs9.03 (2.58)13.8 (2.77)
 Discrepancy, %37.17 (17.62)23.18 (13.63)2.51.020.89
Nonpreferred hand
 Single, no. of pegs13.22 (3.33)17.06 (1.97)3.76.06.1169.54<.001.7036.89<.001.55
 Dual, no. of pegs8.25 (2.67)13.97 (2.28)
 Discrepancy, %34.30 (22.04)18.26 (8.62)2.71.010.96
Both hands
 Single, no. of pegs20.53 (3.63)27.16 (3.26)6.15.02.1733.49<.001.5347.59<.001.61
 Dual, no. of pegs14.44 (4.90)27.72 (4.20)
 Discrepancy, %29.20 (20.16)8.63 (13.93)3.36.0020.78
Table Footer NoteNote. M = mean, SD = standard deviation.
Note. M = mean, SD = standard deviation.×
×
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 = −.50, p = .047). Although the other correlations were not significant, the effect sizes were medium to high (r > −.30, p > .05; Table 3).
Table 3.
Correlation Between Daily Functioning and Discrepancy in Hand Dexterity Under Dual-Task Versus Single-Task Conditions in Participants With Schizophrenia (n = 16)
Correlation Between Daily Functioning and Discrepancy in Hand Dexterity Under Dual-Task Versus Single-Task Conditions in Participants With Schizophrenia (n = 16)×
MeasurePreferred HandNonpreferred HandBoth Hands
rprprp
ADLRS–III−.30.260−.46.080−.50.047
UPSA–B−.31.250−.45.100−.37.160
Table Footer NoteNote. ADLRS–III = total scores on the Activities of Daily Living Rating Scale–III; UPSA–B = total scores on the University of California, San Diego, Performance-Based Skills Assessment–Brief Version.
Note. ADLRS–III = total scores on the Activities of Daily Living Rating Scale–III; UPSA–B = total scores on the University of California, San Diego, Performance-Based Skills Assessment–Brief Version.×
Table 3.
Correlation Between Daily Functioning and Discrepancy in Hand Dexterity Under Dual-Task Versus Single-Task Conditions in Participants With Schizophrenia (n = 16)
Correlation Between Daily Functioning and Discrepancy in Hand Dexterity Under Dual-Task Versus Single-Task Conditions in Participants With Schizophrenia (n = 16)×
MeasurePreferred HandNonpreferred HandBoth Hands
rprprp
ADLRS–III−.30.260−.46.080−.50.047
UPSA–B−.31.250−.45.100−.37.160
Table Footer NoteNote. ADLRS–III = total scores on the Activities of Daily Living Rating Scale–III; UPSA–B = total scores on the University of California, San Diego, Performance-Based Skills Assessment–Brief Version.
Note. ADLRS–III = total scores on the Activities of Daily Living Rating Scale–III; UPSA–B = total scores on the University of California, San Diego, Performance-Based Skills Assessment–Brief Version.×
×
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 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 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 dual-task 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.
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-182-004-MY3), 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 [Article]
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 [Article] ×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
Chu, T.-F. (2004). Manual for the Activities of Daily Living Rating Scale III. New Taipei City, Taiwan: Hua-jian.
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.
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
Fuller, R. L., Van Winkle, E. P., Anderson, K. E., Gruber-Baldini, 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 [Article] [PubMed]
Fuller, R. L., Van Winkle, E. P., Anderson, K. E., Gruber-Baldini, 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 [Article] [PubMed]×
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 [Article]
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 [Article] ×
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. [Article] [PubMed]
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. [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
Kahneman, D. (1973). Attention and effort. Englewood Cliffs, NJ: Prentice-Hall.
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article]
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 [Article] ×
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 [Article] [PubMed]
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 [Article] [PubMed]×
Leifker, F. R., Patterson, T. L., Bowie, C. R., Mausbach, B. T., & Harvey, P. D. (2010). Psychometric properties of performance-based 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 [Article] [PubMed]
Leifker, F. R., Patterson, T. L., Bowie, C. R., Mausbach, B. T., & Harvey, P. D. (2010). Psychometric properties of performance-based 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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
Manning, R. T. (1982). The Serial Sevens Test. Archives of Internal Medicine, 142, 1192. http://dx.doi.org/10.1001/archinte.1982.00340190148022 [Article] [PubMed]
Manning, R. T. (1982). The Serial Sevens Test. Archives of Internal Medicine, 142, 1192. http://dx.doi.org/10.1001/archinte.1982.00340190148022 [Article] [PubMed]×
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. [Article]
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. [Article] ×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
Novak, S., Johnson, J., & Greenwood, R. (1996). Barthel revisited: Making guidelines work. Clinical Rehabilitation, 10, 128–134. http://dx.doi.org/10.1177/026921559601000208 [Article]
Novak, S., Johnson, J., & Greenwood, R. (1996). Barthel revisited: Making guidelines work. Clinical Rehabilitation, 10, 128–134. http://dx.doi.org/10.1177/026921559601000208 [Article] ×
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
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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
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 [Article] [PubMed]
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 [Article] [PubMed]×
Rubinov, M., & Bullmore, E. (2013). Schizophrenia and abnormal brain network hubs. Dialogues in Clinical Neuroscience, 15, 339–349. [PubMed]
Rubinov, M., & Bullmore, E. (2013). Schizophrenia and abnormal brain network hubs. Dialogues in Clinical Neuroscience, 15, 339–349. [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
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/10.1016/0022-3956(91)90006-V. [Article] [PubMed]
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/10.1016/0022-3956(91)90006-V. [Article] [PubMed]×
Smith, A. (1967). The Serial Sevens Subtraction Test. Archives of Neurology, 17, 78–80. http://dx.doi.org/10.1001/archneur.1967.00470250082008 [Article] [PubMed]
Smith, A. (1967). The Serial Sevens Subtraction Test. Archives of Neurology, 17, 78–80. http://dx.doi.org/10.1001/archneur.1967.00470250082008 [Article] [PubMed]×
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 [Article] [PubMed]
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 [Article] [PubMed]×
Tiffin, J., & Asher, E. J. (1948). The Purdue Pegboard: Norms and studies of reliability and validity. Journal of Applied Physiology, 32, 234–247.
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.
World Health Organization. (2010). International statistical classification of diseases and related health problems (10th rev.). Geneva: Author.×
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.
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.
×
Table 1.
Participants’ Demographic and Clinical Characteristics
Participants’ Demographic and Clinical Characteristics×
CharacteristicSchizophrenia Group (n = 16), Mean (SD)Control Group (n = 16), Mean (SD)t or χ2p
Age, yr35.63 (7.80)35.63 (7.80)t (30) = 0.001.00
Gender, n
 Male88χ2(1) < .001.00
 Female88
Education level, yr13.13 (2.53)17.06 (1.48)t (30) = 5.38<.001
Preferred hand, n
 Left23χ2(1) = .24.63
 Right1413
MMSE score28.63 (1.54)29.63 (1.09)t (30) = 2.12.04
Table Footer NoteNote. MMSE = Mini-Mental State Examination; SD = standard deviation.
Note. MMSE = Mini-Mental State Examination; SD = standard deviation.×
Table 1.
Participants’ Demographic and Clinical Characteristics
Participants’ Demographic and Clinical Characteristics×
CharacteristicSchizophrenia Group (n = 16), Mean (SD)Control Group (n = 16), Mean (SD)t or χ2p
Age, yr35.63 (7.80)35.63 (7.80)t (30) = 0.001.00
Gender, n
 Male88χ2(1) < .001.00
 Female88
Education level, yr13.13 (2.53)17.06 (1.48)t (30) = 5.38<.001
Preferred hand, n
 Left23χ2(1) = .24.63
 Right1413
MMSE score28.63 (1.54)29.63 (1.09)t (30) = 2.12.04
Table Footer NoteNote. MMSE = Mini-Mental State Examination; SD = standard deviation.
Note. MMSE = Mini-Mental State Examination; SD = standard deviation.×
×
Table 2.
Participant Performance on the Purdue Pegboard Test
Participant Performance on the Purdue Pegboard Test×
VariableSchizophrenia Group (n = 16), M (SD)Control Group (n = 16), M (SD)t TestCondition × Group EffectCondition EffectGroup Effect
t (30)pdF (1, 30)pPartial η2F (1, 30)pPartial η2F (1, 30)pPartial η2
Preferred hand
 Single, no. of pegs14.47 (1.70)18.06 (1.55)1.79.19.06105.94<.001.7845.27<.001.60
 Dual, no. of pegs9.03 (2.58)13.8 (2.77)
 Discrepancy, %37.17 (17.62)23.18 (13.63)2.51.020.89
Nonpreferred hand
 Single, no. of pegs13.22 (3.33)17.06 (1.97)3.76.06.1169.54<.001.7036.89<.001.55
 Dual, no. of pegs8.25 (2.67)13.97 (2.28)
 Discrepancy, %34.30 (22.04)18.26 (8.62)2.71.010.96
Both hands
 Single, no. of pegs20.53 (3.63)27.16 (3.26)6.15.02.1733.49<.001.5347.59<.001.61
 Dual, no. of pegs14.44 (4.90)27.72 (4.20)
 Discrepancy, %29.20 (20.16)8.63 (13.93)3.36.0020.78
Table Footer NoteNote. M = mean, SD = standard deviation.
Note. M = mean, SD = standard deviation.×
Table 2.
Participant Performance on the Purdue Pegboard Test
Participant Performance on the Purdue Pegboard Test×
VariableSchizophrenia Group (n = 16), M (SD)Control Group (n = 16), M (SD)t TestCondition × Group EffectCondition EffectGroup Effect
t (30)pdF (1, 30)pPartial η2F (1, 30)pPartial η2F (1, 30)pPartial η2
Preferred hand
 Single, no. of pegs14.47 (1.70)18.06 (1.55)1.79.19.06105.94<.001.7845.27<.001.60
 Dual, no. of pegs9.03 (2.58)13.8 (2.77)
 Discrepancy, %37.17 (17.62)23.18 (13.63)2.51.020.89
Nonpreferred hand
 Single, no. of pegs13.22 (3.33)17.06 (1.97)3.76.06.1169.54<.001.7036.89<.001.55
 Dual, no. of pegs8.25 (2.67)13.97 (2.28)
 Discrepancy, %34.30 (22.04)18.26 (8.62)2.71.010.96
Both hands
 Single, no. of pegs20.53 (3.63)27.16 (3.26)6.15.02.1733.49<.001.5347.59<.001.61
 Dual, no. of pegs14.44 (4.90)27.72 (4.20)
 Discrepancy, %29.20 (20.16)8.63 (13.93)3.36.0020.78
Table Footer NoteNote. M = mean, SD = standard deviation.
Note. M = mean, SD = standard deviation.×
×
Table 3.
Correlation Between Daily Functioning and Discrepancy in Hand Dexterity Under Dual-Task Versus Single-Task Conditions in Participants With Schizophrenia (n = 16)
Correlation Between Daily Functioning and Discrepancy in Hand Dexterity Under Dual-Task Versus Single-Task Conditions in Participants With Schizophrenia (n = 16)×
MeasurePreferred HandNonpreferred HandBoth Hands
rprprp
ADLRS–III−.30.260−.46.080−.50.047
UPSA–B−.31.250−.45.100−.37.160
Table Footer NoteNote. ADLRS–III = total scores on the Activities of Daily Living Rating Scale–III; UPSA–B = total scores on the University of California, San Diego, Performance-Based Skills Assessment–Brief Version.
Note. ADLRS–III = total scores on the Activities of Daily Living Rating Scale–III; UPSA–B = total scores on the University of California, San Diego, Performance-Based Skills Assessment–Brief Version.×
Table 3.
Correlation Between Daily Functioning and Discrepancy in Hand Dexterity Under Dual-Task Versus Single-Task Conditions in Participants With Schizophrenia (n = 16)
Correlation Between Daily Functioning and Discrepancy in Hand Dexterity Under Dual-Task Versus Single-Task Conditions in Participants With Schizophrenia (n = 16)×
MeasurePreferred HandNonpreferred HandBoth Hands
rprprp
ADLRS–III−.30.260−.46.080−.50.047
UPSA–B−.31.250−.45.100−.37.160
Table Footer NoteNote. ADLRS–III = total scores on the Activities of Daily Living Rating Scale–III; UPSA–B = total scores on the University of California, San Diego, Performance-Based Skills Assessment–Brief Version.
Note. ADLRS–III = total scores on the Activities of Daily Living Rating Scale–III; UPSA–B = total scores on the University of California, San Diego, Performance-Based Skills Assessment–Brief Version.×
×