Introduction
he elderly population in Iran is growing rapidly so that in 2011 a total of 6.2% of the population of Iran was over 60 years old [1]. According to the World Health Organization forecasts, this rate will increase to 25% between 2040 and 2050 [2]. Aging is a natural phenomenon that causes changes in the cognitive and physical structure and functions [3]. The frontal lobe and its connections, which are responsible for executive functions, are among the structures that are affected by the aging process [4, 5]. Executive function is a cognitive ability that includes the design and execution of purposeful behaviors, abstract thinking, and judgment [6, 7].
Since these abilities require the necessary tools to perform daily activities, even a slight executive function problem can disrupt a person’s performance. For example, several cross-sectional studies have reported that the elderly with low scores on executive function tests have more functional problems than the elderly with normal executive functions [8, 9, 10]. Studies have also confirmed a relationship between low scores on cognitive tests such as Mini–Mental State Examination (MMSE) and functional dependence in the elderly [10, 11]. However, Johnson et al. stated that executive dysfunction is a better predictor of reduced functional independence in basic daily activities and requires tools [11].
Decreased executive functions can lead to more falling [13], more unsatisfactory driving performance, and impaired performance in daily activities that require tools, thereby reducing the independence of the elderly [14, 15, 16]. Executive dysfunction reduces performance and restricts physical activity [17]. Tobimatsu stated that daily activities that require tools arise before the basic activities of daily life [18]. Maintaining performance is important for the independent life of the elderly and reduces the pressure on caregivers, and affects the quality of life of the elderly and caregivers [19, 20, 21, 22].
Studies have revealed that interventions on improving activity were more successful than interventions on relieving symptoms [23]. In an organized review, Coninck et al. examined the effect of occupational therapy on the performance of the elderly, and the results indicated a positive effect of occupational therapy [24].
Early in this century, a client-centered, activity-based approach was developed to address children’s motor problems with developmental coordination disorders (which limited their functioning) using cognitive strategies [25]. In the cognitive approach to daily life activities, an individual first selects personal objectives based on daily activities, and then the therapist teaches the person general problem-solving strategies (goal setting, planning, implementation, checking) [26]. Next, the individual uses these strategies to implement the selected objectives.
In the meantime, the therapist monitors the individual’s performance using dynamic activity analysis. Suppose part of this activity encounters a problem or obstacle. In that case, the therapist, with the help of specific strategies (such as physical condition, attention to how to perform, and make changes or adaptations in the activity), tries to guide the client to find a suitable solution [27]. In this process, called “guided discovery,” instead of providing an answer to the clients, they are guided to find a solution to their problems [28].
Materials and Methods
This research was conducted by a single-subject quasi-experimental method of type A-B with a follow-up period. When the goal is to examine behavioral changes or conduct a new intervention pilot study, using a single-subject study design can be a good choice [29, 30]. This study included a 60-year-old woman and a 64-year-old man who lived in their private houses. Before the intervention, subscales of “Digit Span Forward” (to measure attention) and “Digit Span Backwards” and “Digit Symbol” (to measure working memory) were used to assess the participants’ cognitive status.
The Wisconsin Card Sorting Test assessed the participants’ executive function. This study was conducted in 3 phases. In the first phase, which lasted 2 weeks, initial sessions were held to determine the objectives. The participants’ baseline performance in the selected objectives was evaluated in three evaluation sessions, 5 days apart, using the Performance Quality Rating Scale (PQRS). In this phase, individual performance and satisfaction, daily life activities, and client self-efficacy were evaluated by Canadian Occupational Performance Measure (COPM), Functional Independence Measure (FIM), and tools. In the second phase, which lasted 8-10 sessions, general problem-solving strategies and field-specific strategies were explained to the participants, and then the implementation of the objectives commenced under the supervision of the therapist. At this stage, the performance of clients was evaluated 5 times. Finally, during the follow-up period, participants’ performance was evaluated 3 times with an interval of 1 week. At the end of the intervention and follow-up period, changes in performance and satisfaction, daily life activities, and self-efficacy were assessed.
Canadian Occupational Performance Measure (COPM) 
COPM is a client-centered tool for personal understanding one’s performance in daily life activities. The tool examines 3 areas of activity, including self-care (personal hygiene, functional mobility, and managing community issues), productivity (working with or without pay, home management, play/school), and leisure (quiet recreation, active recreation, social interactions).
An occupational therapist implements this tool. The client is asked to identify performance problems, rank those on a 10-point scale from “trivial” to “extremely important,” and then identify the 5 activities. This tool has been translated into Persian by Dehghan et al. and its “validity” has been reported as 80.95±0.222, and “reliability for performance” and “satisfaction” have been reported as 0.84 and 0.87, respectively [31].
Functional Independence Measure (FIM)
The FIM is a tool to assess the level of functional independence of individuals in daily life activities. This tool has 13 movement items in self-care, sphincter control, movement and transfer, and 5 cognitive items in the areas of communication and social cognition [32]. This tool can be used in all motor defects and all conditions [33]. Naqdi et al. reported the reliability of the Persian version of the test-retest of this tool between 0.88 and 0.98 [34].
Performance Quality Rating Scale (PQRS)
PQRS is used to record performance. For this purpose, the individuals’ performance is filmed, and then the quality of their performance is scored by two evaluators. This scoring is based on the definition of a function that has already been created for the selected objectives of clients by an occupational therapist with experience in the field of activity analysis, from 1 (cannot perform any part of the activity without help) to 10 (complete and appropriate performance of the activity). PQRS is a non-standard tool that requires an experienced evaluator to implement.
Results
Because of this study’s nature, it was impossible to statistically evaluate the tools for assessing functional independence and the COPM. However, the net scores of these tools are presented in Table 1 to show the changes and the descriptive information of the participants. 


In single-subject studies, the results are better interpreted through visual analysis of the graphical data [35, 36]. For this purpose, the rating scale scores for each objective’s quality of performance were sketched on the chart using R software. The evaluator gave these scores to the clients’ performance in three phases (primary, intervention, and follow-up).
Examining the significance of changes was performed using the semi-statistical 2 SD band method. In this method, the change is considered “significant” when at least two consecutive scores are above or below two standard deviations [37]. A visual examination of the graphs reveals that both participants showed fluctuations in their performance in the intervention phase with a general tendency to progress. As measured by the evaluator, this improvement is consistent with the results of the COPM, which indicates performance improvement from the clients’ point of view.
The first participant’s objectives were to wear earrings, prepare breakfast, and use a sewing machine. The first participant received 8 sessions of CO-OP services, of which one session was dedicated to the first objective, two sessions to the second objective, and two sessions to the third objective, and in other sessions, a combination of two or three objectives was considered. Three sessions were dedicated to wearing earrings, five sessions to preparing breakfast, and five sessions using a sewing machine. Figure 1 displays the performance quality scale scores, mean baseline (bottom line), and line 2 (top line) of standard deviation for each of the first participant’s objectives. Significant improvement in the participant’s performance was observed in all objectives during the intervention and follow-up period. Descriptively speaking, the first participant’s performance quality score using the sewing machine in the baseline was almost 4 because she could not complete part or all of the activity. This score increased to 8 during the intervention and then remained constant at 7 during follow-up. This performance improvement was mainly due to the client developing appropriate strategies to implement her chosen objectives.
 The bottom line shows the baseline assessments’ average scores, and the top line represents two standard deviations.The second participant’s objectives included increasing the ability to bathe, improving handwriting, and performing ablutions. He received a total of 9 CO-OP service sessions, of which three sessions were devoted to bathing, two sessions to handwriting improvement, two sessions to ablution, and the remaining two sessions to a combination of the three objectives. In total, bathing was done in 5 sessions, handwriting improvement in 4 sessions, and ablution in 4 sessions. Figure 2 displays the scores of the PQRS, the mean baseline (bottom line), and line 2 (top line) standard deviation for each of the objectives of the second participant.  The results revealed a significant improvement in “bathing” and “handwriting” performance during the intervention and follow-up period. However, there was no statistically significant improvement in ablution performance. Regarding the first objective of this participant, due to the existing cultural issues, it was impossible to perform this activity naturally and photograph it, and therefore simulation was used. The participant performed bath-related activities in the natural environment of the bath without taking off his clothes. The bottom line shows the average scores of the baseline assessments, and the top line represents two standard deviations.
Discussion and Conclusion
The CO-OP approach was first applied in children with developmental coordination disorders to acquire the skills necessary to improve performance using general and specific cognitive strategies. However, its use is not limited to this field, and today its effect in addition to children with developmental coordination disorders, in diagnoses such as cerebral palsy and acquired brain injuries have been confirmed [38]. Also, studies have been conducted since 2009 on the possibility of using CO-OP in other interventions such as stroke and head trauma [39].
These studies have confirmed that people with cognitive disabilities have also set realistic objectives and plan and use cognitive strategies [40]. Dawson et al. were the first to examine the impact of the CO-OP approach on healthy older adults. They observed that this approach improved participants’ performance on practiced and unpracticed objectives, which confirmed that learning could be transferred using this approach [41].
In this study, both participants could set functional objectives related to daily life activities independently. Participants’ performance improved significantly in 5 of the 6 selected objectives, which continued until one month after the intervention. However, the second participant’s performance in his second objective (ablution) did not improve significantly. The change in performance and satisfaction scores given by the participants themselves, although generally improved, showed a decrease in follow-up assessment in some objectives (such as preparing breakfast and handwriting), which after examination, it was found that these objectives were out of their original state and had changed. For example, in the case of handwriting, the original objective was to maintain the status of gripping the pen and write on a straight line, legibly and appropriately sized, but in the follow-up review, the objective was changed, and “signing” replaced the original objective. Also, in the case of an objective such as “ablution,” as a religious practice that required the observance of specific pre-determined rules and principles, it was impossible to make changes in the activity components; only changes in environmental conditions became possible.
Naturally, since satisfaction with such an objective largely depends on the performance of the activity while maintaining all its main criteria, the level of the participant’s satisfaction with his performance in this objective was low. One of the reasons that participants rated their satisfaction or performance below the initial level may be related to the fact that after the interventions and achieving the initial results, the prioritization of objectives for the participants changed. In other words, the initial objective lost its importance, and just achieving the initial objective did not satisfy the participants.
Participant's goals usually develop and change during intervention, and new features may be added to them, so their goals become more complex. It is also possible that as participants’ ability to perform activities increases, their initial perception of their initial performance’s good or bad quality will change. Because in the final evaluation, researchers examine individuals’ performance and satisfaction with the initial objectives set, this change in objectives can reduce the participant’s performance and satisfaction. This fact has been seen in similar studies, such as McEwan et al. study of people with stroke [42].
Although the mechanism of the CO-OP approach and why it improves performance is still unclear and under investigation, we believe that the interaction between some critical features of this approach, such as the use of general cognitive strategies, guided discovery, and motivational factors related to the selectivity of objectives can be the reason for the effects of this approach.
The use of general cognitive and guided discovery strategies for planning and problem-solving in a structured manner is necessary to achieve the goals. This CO-OP structuring of executive processes involved in the acquisition of complex skills may increase learning efficiency. Some studies suggest that motor skills are based mainly on cognition, and to have successful motor learning, movement-related cognitive processes (such as problem-solving, planning, attention, and concentration) should be practiced along with motor patterns [43]. Therefore, in a cognitive-based approach such as CO-OP, it is expected that practicing cognitive strategies along with performing movements will improve performance. Also, many studies have emphasized the role of cognition, especially executive function, in the acquisition of motor skills.
The results of a study that examined the relationship between action and cognition indicate that in complex motor tasks that require response selection, follow-up, and cognitive and executive control, the function of the frontal lobe is constantly observed [44]. Also, involvement of cognitive areas is prominent in the early stages of task learning [45], or when the brain is exposed to pathological damages or aging [46, 47], or when external and environmental requirements for motor activity increase [48]. This evidence suggests that even in activities that are considered purely motor, there are cognitive components that support the use of cognitive-based approaches such as CO-OP. General cognitive strategies in CO-OP (including objective, planning, performance, and reviewing) help people organize their cognitive skills such as planning, problem-solving and evaluating results, and these can increase the effectiveness of motor skills acquisition. 
The improvement reported in the results may be due to the textural nature of the exercises. In this study, all exercises were performed with the participants’ selected objectives, derived from specific, meaningful, and purposeful daily activities. Learning theory in adults predicts that adults’ readiness to learn is related to their perception of what they need and that their learning is problem-oriented and life-focused. In our opinion, individuals’ selection of training activities is one of the essential components of this intervention.

Ethical Considerations
Compliance with ethical guidelines
The purpose and method of the study were explained to the participants. A written consent was obtained and they were assured that their information would remain confidential and that they could leave the study at any time. Assessments and interventions were conducted individually with respect to the privacy of individuals. They would be provided with a copy of the results of the intervention. This study did not cause any harm or cost to the participants.

Funding
This study was extracted from the PhD. dissertation of first author at the Department of Occupational Therapy, Faculty of Rehabilitation Sciences, University of Social Welfare and Rehabilitation Sciences, Tehran.

Authors' contributions
Conceptualization: Nazila Akbarfahimi, Seyed Ali Hosseini; Methodology: Nazila Akbarfahimi, Mohsen Vahedi; Investigation: Mehrdad Saeidi Borujeni, Elaheh Ebrahimi; Writing-original draft: Nazila Akbarfahimi, Mehrdad Saeidi Borujeni, Elaheh Ebrahimi; Writing-review & editing: All author.

Conflict of interest
The authors declared no conflict of interest.

Acknowldgment
The authors would like to thank Mr. Iraj Ebrahimi Ghasemabadian and colleagues at Ramsar Health Center for helping us access the study participants. We also thank the participants in this study and their families for their support during the study.


References

1. Afshar PF, Asgari P, Shiri M, Bahramnezhad F. A review of the Iran’s elderly status according to the census records. Galen Medical Journal. 2016; 5(1):1-6. http://www.gmj.ir/index.php/gmj/article/view/397
2. Sadeghu R. [Population and development in Iran: Dimensions and challenges (Persian)]. Tehran: National Population Studies & Comprehensive Management Institute; 2009.
3. Chehelamirani N, Sahaf R, Rassafiani M, Bakhshi E. [Validity and reliability of WHOQOL-DIS Questionnaire in Iranian older people with disability (Persian)]. Archives of Rehabilitation. 2016; 16(4):334-45. https://rehabilitationj.uswr.ac.ir/browse.php?a_id=1708&slc_lang=en&sid=1&ftxt=1
4. Buckner RL. Memory and executive function in aging and AD: Multiple factors that cause decline and reserve factors that compensate. Neuron. 2004; 44(1):195-208. [DOI:10.1016/j.neuron.2004.09.006] [PMID]
5. Ohnishi T, Matsuda H, Tabira T, Asada T, Uno M. Changes in brain morphology in Alzheimer disease and normal aging: Is Alzheimer disease an exaggerated aging process? American Journal of Neuroradiology. 2001; 22(9):1680-5. http://www.ajnr.org/content/22/9/1680.short
6. Lezak MD, Howieson DB, Loring DW, Fischer JS. Neuropsychological assessment. Oxford: Oxford University Press; 2004.
7. Cahn-Weiner DA, Malloy PF, Boyle PA, Marran M, Salloway SJTCN. Prediction of functional status from neuropsychological tests in community-dwelling elderly individuals. The Clinical Neuropsychologist. 2000; 14(2):187-95. [DOI:10.1076/1385-4046(200005)14:2;1-Z;FT187]
8. Carlson MC, Fried LP, Xue QL, Bandeen-Roche K, Zeger SL, Brandt J, et al. Association between executive attention and physical functional performance in community-dwelling older women. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences. 1999; 54(5):S262-S70. [DOI:10.1093/geronb/54B.5.S262] [PMID]
9. Grigsby J, Kaye K, Baxter J, Shetterly SM, Hamman R. Executive cognitive abilities and functional status among community-dwelling older persons in the San Luis valley health and aging study. Journal of the American Geriatrics Society. 1998; 46(5):590-6. [DOI:10.1111/j.1532-5415.1998.tb01075.x] [PMID]
10. Agüero-Torres H, Thomas VS, Winblad B, Fratiglioni L. The impact of somatic and cognitive disorders on the functional status of the elderly. ournal of Clinical Epidemiology. 2002; 55(10):1007-12. [DOI:10.1016/S0895-4356(02)00461-4]
11. Johnson JK, Lui LY, Yaffe K. Executive function, more than global cognition, predicts functional decline and mortality in elderly women. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences. 2007; 62(10):1134-41.‏ [DOI:10.1093/gerona/62.10.1134] [PMID] [PMCID]
12. Rastegar M, Hoseini SH, Naser Melli M, Taffah M. The effects of age and walking speeds on vertical ground reaction force in younger and older adults. Journal of Rehabilitation. 2017; 17(4):290-9. [DOI:10.21859/jrehab-1704290]
13. Anstey KJ, Wood J, Lord S, Walker J. Cognitive, sensory and physical factors enabling driving safety in older adults. Clinical Psychology Review. 2005; 25(1):45-65. [DOI:10.1016/j.cpr.2004.07.008] [PMID]
14. Herman T, Mirelman A, Giladi N, Schweiger A, Hausdorff JM. (2010). Executive control deficits as a prodrome to falls in healthy older adults: A prospective study linking thinking, walking, and falling. Journals of Gerontology Series A: Biomedical Sciences and Medical Sciences. 2010; 65(10):1086-92. [DOI:10.1093/gerona/glq077] [PMID] [PMCID]
15. Royall DR, Lauterbach EC, Kaufer D, Malloy P, Coburn KL, Black KJ. The cognitive correlates of functional status: A review from the Committee on Research of the American Neuropsychiatric Association. The Journal of Neuropsychiatry and Clinical Neurosciences. 2007; 19(3):249-65.‏ [DOI:10.1176/jnp.2007.19.3.249] [PMID]
16. Melis R, Van Eijken M, Teerenstra S, Van Achterberg T, Parker S, Borm G, et al. A randomised study of a multidisciplinary programme to intervene on geriatric syndromes in vulnerable older people who live at home (Dutch EASYcare Study). Journals of Gerontology A, Biological Sciences and Medical Sciences. 2008; 63(3):283-90. [DOI:10.1093/gerona/63.3.283] [PMID]
17. Tobimatsu YJ. [Locomotive syndrome: its clinical features and aggravation process (Japanese)]. Bone Joint Nerve. 2014; 4(3):467-72.
18. Sh S, Takian A, Sari A, Kamali M, Majdzadeh S, Karami Matin B. [Disregarded health problems of people with disabilities: A qualitative study of policymakers’ perspective (Persian)]. Archives of Rehabilitation. 2019; 20(2):136-49. [DOI:10.32598/rj.20.2.136]
19. Peters M, Jenkinson C, Doll H, Playford ED, Fitzpatrick R. arer quality of life and experiences of health services: a cross-sectional survey across three neurological conditions. Health and Quality of Life Outcomes. 2013; 11(1):103. [DOI:10.1186/1477-7525-11-103] [PMID] [PMCID]
20. Banimahdi R, Akbarfahimi N, Sahaf R, Rezasoltani P. [Comparing the attitudes of occupational therapy students and alumni towards old people (Persian)]. Iranian Journal of Ageing. 2019; 14(1):64-73. http://salmandj.uswr.ac.ir/article-1-1438-en.html
21. Kazemi N, Sajjadi H, Bahrami G. Quality of life in Iranian elderly. Dspace Repository; 2019. [DOI:10.32598/SIJA.13.Special-Issue.518]
22. Glendinning C, Clarke S, Hare P, Maddison J, Newbronner L. Progress and problems in developing outcomes-focused social care services for older people in England. Health & Social care in the Community. 2008; 16(1):54-63. [DOI:10.1111/j.1365-2524.2007.00724.x] [PMID]
23. De Coninck L, Bekkering GE, Bouckaert L, Declercq A, Graff MJ, Aertgeerts B. Home and community based occupational therapy improves functioning in frail older people: A systematic review. Journal of the American Geriatrics Society. 2017; 65(8):1863-9. [DOI:10.1111/jgs.14889] [PMID]
24. Polatajko HJ, Mandich AD, Missiuna C, Miller LT, Macnab JJ, Malloy-Miller T, et al. Cognitive Orientation to daily Occupational Performance (CO-OP) part III-the protocol in brief. Physical & Occupational Therapy in Pediatrics 2001; 20(2-3):107-23. [DOI:10.1080/J006v20n02_07]
25. Rodger S, Pham C, Mitchell S. Cognitive strategy use by children with Asperger’s syndrome during intervention for motor based goals. Australian Occupational Therapy Journal. 2009; 56(2):103-11. [DOI:10.1111/j.1440-1630.2007.00719.x] [PMID]
26. McEwen S, Polatajko H, Baum C, Rios J, Cirone D, Doherty M, et al. Combined cognitive-strategy and task-specific training improve transfer to untrained activities in subacute stroke: an exploratory randomized controlled trial. Neurorehabilitation and Nneural repair. 2015; 29(6):526-36. [DOI:10.1177/1545968314558602] [PMID] [PMCID]
27. Polatajko HJ, McEwen SE, Ryan JD, Baum C. Pilot randomized controlled trial investigating cognitive strategy use to improve goal performance after stroke. American Journal of Occupational Therapy. 2012; 66(1):104-9. [DOI:10.5014/ajot.2012.001784] [PMID]
28. McEwen SE, Polatajko HJ, Huijbregts MP, Ryan J. Exploring a cognitive-based treatment approach to improve motor-based skill performance in chronic stroke: Results of three single case experiments. Brain Injury. 2009; 23(13-14):1041-53. [DOI:10.3109/02699050903421107] [PMID]
29. Ng EM, Polatajko HJ, Marziali E, Hunt A, Dawson D. Telerehabilitation for addressing executive dysfunction after traumatic brain injury. Brain Injury. 2013; 27(5):548-64. [DOI:10.3109/02699052.2013.766927] [PMID]
30. Dawson DR, Binns MA, Hunt A, Lemsky C, Polatajko HJ. Occupation-based strategy training for adults with traumatic brain injury: A pilot study. Archives of Physical Medicine and Rehabilitation 2013; 94(10):1959-63. [DOI:10.1016/j.apmr.2013.05.021] [PMID]
31. Dawson DR, Gaya A, Hunt A, Levine B, Lemsky C, Polatajko HJ. Using the Cognitive Orientation to Occupational Performance (CO-OP) with adults with executive dysfunction following traumatic brain injury. Canadian Journal of Occupational Therapy. 2009; 76(2):115-27. [DOI:10.1177/000841740907600209] [PMID]
32. Franzen MD, Harris CV. Neuropsychological rehabilitation: Application of a modified multiple baseline design. Brain Injury. 1993; 7(6):525-34. [DOI:10.3109/02699059309008180] [PMID]
33. Ottenbacher KJ. Evaluating clinical change: Strategies for occupational and physical therapists. Philadelphia: Williams & Wilkins; 1986.
34. Dehghan L, Dalvand H, Pourshahbaz A. [Translation of Canadian occupational performance measure and testing Persian version validity and reliability among Iranian mothers of children with cerebral palsy (Persian)]. Journal of Modern Rehabilitation. 2015; 9(4), 25-31.‏ http://mrj.tums.ac.ir/article-1-5349-en.html
35. Linacre JM, Heinemann AW, Wright BD, Granger CV, Hamilton BB. The structure and stability of the functional independence measure. Archives of Physical Medicine and Rehabilitation. 1994; 75(2):127-32. [DOI:10.1016/0003-9993(94)90384-0]
36. Ottenbacher KJ, Hsu Y, Granger CV, Fiedler RC. The reliability of the functional independence measure: A quantitative review. Archives of Physical Medicine and Rehabilitation. 1996; 77(12):1226-32. [DOI:10.1016/S0003-9993(96)90184-7]
37. Naghdi S, Ansari NN, Raji P, Shamili A, Amini M, Hasson S, et al. Cross-cultural validation of the Persian version of the Functional Independence Measure for patients with stroke. Disability and Rehabilitation. 2016; 38(3):289-98. [DOI:10.3109/09638288.2015.1036173] [PMID]
38. Martini R, Rios J, Polatajko H, Wolf T, McEwen S. The Performance Quality Rating Scale (PQRS): Reliability, convergent validity, and internal responsiveness for two scoring systems. Disability and Rehabilitation 2015; 37(3):231-8. [DOI:10.3109/09638288.2014.913702] [PMID]
39. Kazdin AE. Single-case research designs: Methods for clinical and applied settings. New York: Oxford University Press; 1982.
40. Kratochwill TR, Levin JR, Horner RH, Swoboda CM. Single-case intervention research: Methodological and statistical advances. Kratochwill TR, Levin JR, editors. Washington, DC, US: American Psychological Association; 2014.
41. Sideridis GD, Greenwood CR. Evaluating treatment effects in single-subject behavioral experiments using quality-control charts. Journal of Behavioral Education. 1996; 6(2):203-11. [DOI:10.1007/BF02110233]
42. Lee TD, Swinnen SP, Serrien DJ. Cognitive effort and motor learning. Quest. 1994; 46(3):328-44. [DOI:10.1080/00336297.1994.10484130]
43. Serrien DJ, Ivry RB, Swinnen SP. The missing link between action and cognition. Progress in Neurobiology. 2007; 82(2):95-107. [DOI:10.1016/j.pneurobio.2007.02.003] [PMID]
44. Debaere F, Wenderoth N, Sunaert S, Van Hecke P, Swinnen SP. Changes in brain activation during the acquisition of a new bimanual coordination task. Neuropsychologia. 2004; 42(7):855-67. [DOI:10.1016/j.neuropsychologia.2003.12.010] [PMID]
45. Murase N, Duque J, Mazzocchio R, Cohen LG. Influence of interhemispheric interactions on motor function in chronic stroke. Annals of Neurology: Official Journal of the American Neurological Association and the Child Neurology Society. 2004; 55(3):400-9. [DOI:10.1002/ana.10848] [PMID]
46. Wu T, Hallett M. A functional MRI study of automatic movements in patients with Parkinson’s disease. Brain. 2005; 128(10):2250-9. [DOI:10.1093/brain/awh569] [PMID]
47. Jantzen K, Oullier O, Marshall M, Steinberg F, Kelso JAS. A parametric fMRI investigation of context effects in sensorimotor timing and coordination. Neuropsychologia. 2007; 45(4):673-84. [DOI:10.1016/j.neuropsychologia.2006.07.020] [PMID] [PMCID]
48. Merriam SB, Caffarella RS, Baumgartner LM. Learning in adulthood: A comprehensive guide. Hoboken: John Wiley & Sons; 2006.