The Sony PlayStation II EyeToy: Low-Cost Virtual Reality for Use in Rehabilitation

Rand, Debbie OT, PhD; Kizony, Rachel OT, PhD; Weiss, Patrice (Tamar) L. OT, PhD

Journal of Neurologic Physical Therapy:
doi: 10.1097/NPT.0b013e31818ee779

The objective of this study was to investigate the potential of using a low-cost video-capture virtual reality (VR) platform, the Sony PlayStation II EyeToy, for the rehabilitation of older adults with disabilities. This article presents three studies that were carried out to provide information about the EyeToy's potential for use in rehabilitation. The first study included the testing of healthy young adults (N = 34) and compared their experiences using the EyeToy with those using GestureTek's IREX VR system in terms of a sense of presence, level of enjoyment, control, success, and perceived exertion. The second study aimed to characterize the VR experience of healthy older adults (N = 10) and to determine the suitability and usability of the EyeToy for this population and the third study aimed to determine the feasibility of the EyeToy for use by individuals (N = 12) with stroke at different stages. The implications of these three studies for applying the system to rehabilitation are discussed.

Author Information

Laboratory for Innovations in Rehabilitation Technology, Department of Occupational Therapy, University of Haifa, Mount Carmel, Haifa, Israel (D.R., R.K., P.L.W.).

Address correspondence to: Debbie Rand,;

Article Outline
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Recent studies of neural plasticity and motor function retraining suggest that multiple repetitions of movement are essential to regain function.1,2 A great disparity exists between the number of repetitions experimental animals are required to do (400–600 repetitions per day) compared with the number of times a movement or task is practiced during rehabilitation therapy as documented by observation of participants with stroke who received occupational and physical therapy at an outpatient rehabilitation clinic.3 For example, during a single session of upper extremity therapy, there were only 39 repetitions of active movement, 34 repetitions of passive movement, and 12 repetitions of purposeful movements.3 This limited amount of practice decreases still further once clients finish their active rehabilitation programs, an outcome that is alarming in view of the early discharge policy implemented in many countries to reduce hospitalization costs.4,5 Moreover, most clients do not exercise by themselves between sessions or when they are at home after discharge.

Increasing the intensity and duration of rehabilitation to improve the quality of life of individuals with chronic diseases such as stroke can be achieved through physical activity because it reduces morbidity and prevents the development of secondary chronic diseases.6,7 Novel methods are needed to provide opportunities for functional activities that will increase the number of repetitions of purposeful movements during therapy and will support the implementation of home exercise programs.3 Maintaining the motivation of people to exercise independently at home is a related challenge because many exercise programs are monotonous and boring.8

Virtual reality (VR)–based therapy appears to provide an answer to these challenges. VR typically refers to the use of interactive simulations created with computer hardware and software to present users with opportunities to engage in environments that appear and feel similar to real-world objects and events.9,10 Users interact with displayed images, move and manipulate virtual objects, and perform other actions in a way that immerse them in the simulated environment thereby engendering a subjective feeling of presence in the virtual world. To achieve a stronger feeling of presence, users are provided with different feedback modalities such as visual and audio feedback.11 Depending on the characteristics of hardware, software, and task complexity, VR-based therapy aims to provide users with a meaningful experience in the context of the user's therapeutic objectives.

VR is considered appropriate for rehabilitation because of its well-known assets. These include the opportunity for active learning, which encourages and motivates the participant,12 the ability to objectively measure behavior in a challenging but safe and ecologically valid environment while maintaining strict experimental control over stimulus delivery and measurement. Another asset is the capacity to individualize treatment needs while gradually increasing the complexity of tasks and decreasing the support provided by the clinician.13,14 Several studies have reported that participants experienced high levels of enjoyment while interacting within virtual environments developed for rehabilitation14,15 and achieved a high degree of repetitions.16 This may lead to greater motivation to exercise more17 between sessions or at home.

For the past few years, a number of clinical research groups have explored the therapeutic potential of GestureTek's Gesture Xtreme and its rehabilitation counterpart, IREX VR ( IREX is a projected video-capture system in which participants stand or sit in a demarcated area, in front of a chroma key green backdrop, viewing a large monitor that displays an environment or functional tasks, such as touching virtual balls. A single-camera, vision-based tracking system captures and converts the user's movements for processing; the user's live, onscreen video image corresponds in real time to his or her movements, leading to engagement in the simulated task.18

This system was originally developed for entertainment purposes and has since been adapted for use in rehabilitation.19–21 Different researchers have investigated this system,15,18,22–25 demonstrating its suitability for use during the rehabilitation of people with disabilities caused by motor and/or cognitive deficits. Results from small samples have also demonstrated its potential for training the upper extremity after stroke and even showed evidence of brain plasticity associated with the use of VR.26 Its advantages include the fact that clients see themselves rather than being represented by an avatar. They do not have to wear special apparatus, such as gloves or sensors, which encourages the use of active movement, nor do they have to wear a head-mounted display, which reduces their chance of experiencing cybersickness side effects. In addition, the therapist can intervene easily during the session to support and guide the person's movements.18,19

Although the advantages of VR in general, and the IREX in particular, have become widely recognized within the clinical community, the rehabilitation team faces a daunting challenge—to find an off-the-shelf VR system that enables achievement of the goals stated above, yet affordable by the typical clinical facility27,28 or for individual home use.29

The PlayStation 2 EyeToy,30 released by Sony, Inc., in the early 2000s, is an off-the-shelf, low-cost gaming application that provides the opportunity to interact with virtual objects that can be displayed on a standard TV monitor. As with the IREX system, the EyeToy displays real-time images of the user. However, it requires neither a chroma key backdrop behind the user nor bright ambient lighting, which is necessary when running IREX applications. This makes for an easier setup of the system in any location but means that users see themselves manipulating virtual objects within a virtual environment that is superimposed on an image of the actual physical surrounding. EyeToy applications include many motivating and competitive environments that can be played by one or more players (eg, boxing, spinning plates) as well as different visual effects that encourage active movement without giving a score (eg, painting a rainbow, mirror image distortions, and popping bubbles). To date, Sony has released a number of compact discs that contain applications for the EyeToy that include functional tasks such as acting as a chef in a kitchen or serving meals in a fast-food restaurant. The EyeToy's low cost and easy setup are advantages that have encouraged us to consider its use in rehabilitation and to investigate its usability for wide segments of the population and not just for children who were the original population targeted by this system.

Various clinical settings have started to use the Sony PlayStation 2 EyeToy as part of rehabilitation,31 and recently two studies using the EyeToy for intervention were published. Lotan et al32 reported an improvement in the physical fitness of 30 individuals (mean age = 52.3 ± 5.8 years) with intellectual and developmental disability following a five- to six-week intervention (two 30-minute sessions per week) with the EyeToy; no improvement was seen in the physical fitness of an age-matched control group. Yavuzer et al33 reported results from a randomized, controlled study in which the EyeToy was used as an intervention tool for training movements of the paretic upper extremity during subacute rehabilitation after stroke in addition to the conventional therapy. Ten subjects participated in daily 30-minute therapy sessions for four weeks, whereas another 10 participants in a control group only watched the EyeToy games. They reported a significant improvement in the upper extremity movement and in self-care of the participants in the experimental group only. In addition, two case studies reported using the EyeToy for clients with burns34 and for a participant with stroke.6

Although these studies have demonstrated the application of the EyeToy with different populations and have shown that it may be an effective tool for rehabilitation, this system has not yet been assessed in a systematic manner. Therefore, the current study aimed to characterize the EyeToy and to determine its advantages and limitations as a tool for rehabilitation of older adults and individuals with stroke at different stages. This was achieved by conducting three separate studies focusing on these specific goals: (1) to compare the performance, side effects, sense of presence, enjoyment, and exertion evoked by two applications of the EyeToy to those evoked by two IREX applications; (2) to characterize the EyeToy experience of healthy older adults and to determine the suitability and usability of the EyeToy for this population; and (3) to determine the feasibility of the EyeToy for use by individuals with stroke at different stages of recovery. In addition, the sensitivity of the EyeToy to differences in user characteristics was probed by comparing the performance of the populations assessed in the three studies (healthy younger adults, healthy older adults, and adults with stroke).

All studies were approved by the University of Haifa Institutional Review Board, and all eligible subjects gave written informed consent before their participation.

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Objective and Hypotheses

To compare the performance, side effects, sense of presence, enjoyment, and exertion evoked by several applications of the EyeToy to those evoked by several IREX applications. We hypothesized that presence, but not exertion or enjoyment would differ between the two VR systems. We hypothesized that presence, enjoyment, and exertion would differ between the four environments.

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Thirty-four young participants without a disability, aged 19–40 years (mean age ± SD = 26.3 ± 4.5), 17 females and 17 males, volunteered to participate in the study.

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VR Systems and Environments

The IREX VR system was used with two virtual environments, Soccer [preventing balls from entering the goal (Figure 1a)] and Birds and Balls [touching balls that approach the user in a pastoral setting (Figure 1b)]. Both games require visual scanning and prompt response by the upper extremity to virtual stimuli dependent on the level of the game.15,18 These environments were chosen because our previous work has shown them to be suitable for use by various rehabilitation populations.15,18,19 The Sony PlayStation EyeToy was used with two virtual environments, Kung-Foo (Figure 1c) and Wishy-Washy (Figure 1e). These two environments were selected for their diverse characteristics; Kung-Foo environment requires visual attention to both sides of the screen and rapid movements in response to virtual opponents whereas Wishy-Washy entails slower, less specific actions related to a functional task (washing windows). It was not possible to find equivalent environments from both VR systems but for all four environments the participants were required to move their arms while maintaining whole-body balance to interact with virtual stimuli in a task-specific manner.

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Presence Questionnaire (PQ)

The PQ of Witmer and Singer35 was translated into Hebrew with the authors' permission and used to assess the users' sense of presence. Participants responded to 19 items using a seven-point scale to rate various experiences within the virtual environment; the maximum total score is 133 points, indicating a high level of presence. The items assess different aspects of presence including involvement, control, natural, interface quality, and resolution. High internal consistency reliability (α = 0.88) was reported by Witmer and Singer. The internal consistency reliability of the Hebrew version was found to be α = 0.89.36

On the basis of comments of Slater et al37 about the construct of presence, an additional question was asked: “During the time of the experience, which was strongest on the whole, your sense of being in the virtual environment, or of being in the real world of the laboratory?” This question was rated on a scale from one (being in the real world of the laboratory) to seven (being in the virtual environment).

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Short Feedback Questionnaire (SFQ)

The SFQ is based, in part, on a translated version of the PQ of Witmer and Singer and was administered after each environment (virtual game). These six items assessed the participant's (1) feeling of enjoyment, (2) sense of being in the environment, (3) success, (4) control, (5) perception of the environment as being realistic, and (6) whether the feedback from the computer was understandable. Responses to all questions were rated on a five-point scale, which were combined to give a global response to the experience for a maximum score of 30. An additional question was added to inquire whether the participants felt any discomfort during the experience. Internal consistency reliability of the SFQ ranged between α = 0.70 and α = 0.81 for different virtual environments. The concurrent validity of the presence part of the SFQ was established by determining correlations between the scores in the SFQ and the scores in the PQ. The correlations found were significant (P < 0.005) but moderate and ranged from r = 0.55 to r = 0.74 for different virtual environments.38 The total SFQ scores for each environment are presented. Because enjoyment is a key factor for enhancing motivation, the results from the first question of the SFQ, regarding enjoyment, are also presented separately.

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Borg's Scale of Perceived Exertion

This scale was used to assess how much physical effort the participants reported expending during each virtual environment experience.39 This is a 20-point scale that participants rated from six (no exertion at all) to 20 (maximal exertion).

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Performance Within the EyeToy

Performance was monitored using scores provided by each environment. For the Wishy-Washy environment, the number of windows washed during a period of 180 seconds was recorded and for Kung-Foo, the number of enemies repelled was recorded.

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Each participant experienced the two virtual environments for 180 seconds in addition to 60 seconds of practice on each of the EyeToy and IREX VR systems in a counterbalanced order. After experiencing each virtual environment, the participants were asked to complete the SFQ and rate their perceived exertion. After experiencing the two environments using the first VR system, the Witmer and Singer PQ was completed and the additional presence question from Slater et al was answered. Participants then underwent the same procedure with the second VR system. The entire experimental procedure took place during a single 40-minute session in a VR laboratory located on a university campus. At the end of the procedure, the participants were asked which of the four environments they found to be most and least enjoyable.

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Data Analysis

Paired t tests were used to determine differences between the sense of presence for the EyeToy system compared with the IREX system (using the PQ and the Slater et al presence question). Repeated-measures analysis of variance (α < 0.05) were used to assess differences between the four virtual environments (for the total SFQ, the level of enjoyment, and perceived exertion). This was followed by paired t tests to identify the source of the significance.

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There were no significant differences due to the order in which the VR systems were experienced by participants for any of the outcome measures. The data were henceforth pooled. Data are presented in Table 1.

Participants felt a great sense of presence while interacting in both VR systems, with no significant difference between them. The mean total PQ score for the IREX system was 95.9 ± 1.9 (maximum of 133 points) compared with 96.0 ± 1.5 for the EyeToy system. The mean scores for the Slater et al presence question was 3.6 ± 1.3 (out of a maximum score of seven points) for the IREX system vs 4.01 ± 1.7 for the EyeToy system.

Significant main effect of application on the mean SFQ (F(15) = 5.970, P < 0.007) was found. As presented in Table 1, the mean SFQ scores for all four environments were relatively high, ranging from 21.5 to 25.7 out of a maximum 30 points. The SFQ score for Kung-Foo was significantly higher than the scores for Soccer (t(33) = −5.9, P < 0.001), Birds and Balls (t(33) = −6.7, P < 0.001), and Wishy-Washy (t(33) = −2.5, P < 0.01). In some cases, eg, Kung-Foo vs Wishy-Washy, the actual difference in SFQ were small (1.5 points) and likely not to have any functional significance. In contrast, the SFQ scores for Soccer and Birds and Balls were four points lower, clearly indicative of their being perceived to be less enjoyable and motivating than Kung-Foo.

Level of enjoyment (the first question of the SFQ) was found to be significantly different (F(15) = 12.06, P < 0.00). The greatest enjoyment was reported for Kung Foo with differences as follows: between Kung-Foo and Birds and Balls (t(33) = −9.57, P < 0.000), between Kung-Foo and Soccer (t(33) = −4.806, P < 0.000), and between Kung-Foo and Wishy-Washy (t(33) = −3.88, P < 0.001. Soccer was reported as more enjoyable than Birds and Balls (t(33) = −2.56, P < 0.001).

Perceived exertion was significantly different between each of the four environments (F(15) = 12.068, P < 0.000). Birds and Balls was reported to be significantly easier than Soccer (t(33) = −9.1, P < 0.000), Wishy-Washy (t(33) = −5.5, P < 0.001), and Kung-Foo (t(33) = −6.13, P < 0.001).

To further characterize the Eyetoy, differences between genders were examined. There were no differences in the sense of presence between the male and female participants but there were significant differences in the level of perceived exertion, perhaps due to the differences in performance. Significant differences were found for performance within the two environments of the EyeToy system. The mean total number of windows cleaned in the Wishy-Washy game was 11.1 ± 2.2 for the men which was significantly higher compared with the number of windows the women managed to clean (5.4 ± 1.9 windows) (t(32) = 7.8, P < 0.001). The mean number of enemies that were repelled in the Kung-Foo game was 141.8 ± 12.5 for the men which was significantly higher than the 82.8 ± 51.4 enemies repelled by the women (t(32) = 4.5, P < 0.001).

The hypothesis that there would be significant differences in the sense of presence between the IREX and EyeToy systems was rejected. However, differences between the four virtual environments were found.

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Objectives and Hypotheses

To characterize the EyeToy gaming experience, by measuring presence, enjoyment and exertion of healthy older adults. To compare the performance on the EyeToy between the young adults in study 1 and the healthy older adults in study 2. We hypothesized that healthy adults would have a high sense of presence and would find the EyeToy gaming experience enjoyable but their performance would be inferior to that of the younger adults.

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Ten older adults without a disability (six women and four men) aged 59–80 years (mean age = 70.0 ± 5.7 years) who lived at home were tested.

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VR System and Environments

Sony's PlayStation 2 EyeToy was used with three virtual environments. Two of the environments (Wishy-Washy and Kung-Foo) are described above. A third environment, Keep-Ups, shown in Figure 1d, required the participant to keep a virtual soccer ball in the air by continually juggling it.

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The participants' perceived sense of presence, enjoyment, and exertion were assessed using the SFQ and Borg scales, described above. In addition, to assess the usability of the EyeToy system, specifically, how easy it is to operate the system, the System Usability Scale (SUS)40 was employed. This questionnaire includes 10 items which provide a global view of subjective assessment of a system's usability. Each item was rated on a five-point scale from one (disagree totally) to five (agree totally). Five items are positive statements, such as “I think that I would like to use this system frequently” and “I thought the system was easy to use” and the other five items are negative, for example, “I found the system unnecessarily complex” and “I think that I would need the support of a technical person to be able to use this system.” The item scores were calculated to give an overall score ranging from 10 to 100 points. The SUS has been shown by the authors to be a robust and reliable evaluation tool,40 but its psychometric properties have not been fully investigated.

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The participants experienced the EyeToy games in their homes after it was set up for them. Each of the three environments was used for 180 seconds preceded by 60 seconds for practice. After each environment they completed the SFQ and rated their perceived exertion. The participant's performance within each environment was recorded manually from the screen display window. During their experience, the researcher operated the EyeToy system while explaining to the participants how it was done. At the end of the session, the participants were requested to independently exit the Kung-Foo environment and to commence the Keep-Ups environment again. The sequence of their actions was recorded. They then completed the SUS.

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Data Analysis

Nonparametric statistics were used because the sample was abnormally distributed. To assess differences between the three environments for the total SFQ, the first question of the SFQ (level of enjoyment) and the perceived exertion, the Friedman test was used. This was followed by the Wilcoxon test between each of the two environments. The Mann-Whitney nonparametric test for two independent samples was used to compare the results of the 10 older adults with those of the 34 younger participants from study 1 in terms of their SFQ, perceived exertion, and performance in two of the environments (Wishy-Washy and Kung-Foo).

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All the participants enjoyed their experience with the EyeToy. The sense of presence as depicted by the total SFQ score was significantly different between the environments (χ2 = 12.74, P < 0.002). The highest SFQ score was for the Wishy-Washy environment (25.3 ± 3 points) followed by the Kung-Foo environment (23.2 ± 4.5 points). Both of these SFQ scores were significantly higher than the scores for Keep-Ups (18.0 ± 5.7, Z = −2.52, P < 0.012 and Z = −2.68, P < 0.007, respectively).

The level of enjoyment (question 1 on the SFQ) was significantly different for the three environments (χ2 = 7.35, P < 0.02); participants enjoyed Kung-Foo (4.5 ± 0.7 points) significantly more than Keep-Ups (3.5 ± 1.0 points, Z = −2.45, P < 0.014). The perceived exertion for all three environments was easy, with no significant differences between them. The mean score for the SUS was 82.7 ± 8.1 points (range = 75.0–97.5 out of a maximum of 100 points), indicating that the participants were capable of operating the system independently.

Significant differences were found for the performance of the young and healthy adults, but not for their sense of presence, enjoyment, or exertion. When playing in the Wishy-Washy environment, participants from the older group succeeded in cleaning a mean of five windows during the 180-second play period, whereas the younger group cleaned a mean of eight windows during the same time period (Z = −2.06, P < 0.038). In the Kung-Foo environment the older participants repelled less than half the number of enemies during a single game than did the younger participants (46 vs 112 enemies, Z = −3.49, P < 0.001). The VR experience for all participants was 180 seconds long. Most of the young participants were able to complete one full game, taking 180 seconds to do so. In contrast, the older participants who were eliminated faster by the Kong-Foo enemies had to play additional games to complete the 180 seconds. Therefore the older adults played 1.9 ± 1.1 games on average during the 180 seconds experience. This difference was significant (Z = −4.32, P < 0.001).

In summary, the EyeToy was found to be suitable for older adults and operated easily by them. Differences in the performance of the younger vs older group indicate that the EyeToy captured differences between younger and older adult characteristics.

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To determine the feasibility of using the EyeToy for individuals with stroke who are at different recovery stages.

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Twelve individuals with stroke participated in this study. Seven participants were at a chronic stage of rehabilitation (one to five years after stroke) and included four men and three women aged 50–80 years (mean ± SD = 63 ± 11 years). They had all sustained a right hemispheric stroke, lived at home, and were fully or partially independent in basic activities of daily living and instrumental activities of daily living even though they had a moderate to severe motor impairment of the left upper extremity. Six of these seven participants walked independently using a walking aid, and one was independent in mobility using a wheelchair. An additional five participants were at a subacute stage of rehabilitation (one to three months after stroke). They included four women and one man, aged 59–91 years (mean ± SD = 73 ± 11 years). They all used wheelchairs and were dependent on others for the basic activities of daily living with moderate to severe motor impairment of their affected upper extremity. Three participants had sustained a left hemispheric stroke, and two participants a right hemispheric stroke. One participant had dysphasia.

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The Sony PlayStation 2 EyeToy was used with the Wishy-Washy and Kung-Foo environments. Participants' gaming experiences were characterized by using the SFQ and Borg's Scale of Perceived Exertion as described above. The points generated by the EyeToy system for each of the two environments were recorded.

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The participants with chronic stroke experienced the two environments at home or at a rehabilitation center (where they came especially to participate in this study), whereas the participants in a subacute rehabilitation program experienced the environments at the hospital. As in study 2, each of the two environments (Wishy-Washy and Kung-Foo) was used for 180 seconds proceeded by 60 seconds for practice. After each environment they were asked to fill in the SFQ and rate their perceived exertion.

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Data Analysis

Because of the small sample size and heterogeneous characteristics of the sample tested in this study, only descriptive statistics were used; in some cases, it was only possible to report on participants' performance and response to the experience in the EyeToy as observed by the researcher.

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As shown in Table 2, all the participants in the chronic group enjoyed Kung-Foo more than Wishy-Washy, but the mean SFQ scores for both games was high (>26/30). The participants rated their perceived exertion as slightly higher for Kung-Foo and all reported fatigue of their weak upper extremity because they were encouraged to use both arms for interaction. The five participants with subacute stroke enjoyed the experience very much and said they would happily repeat it. However, two of the participants in this group became somewhat frustrated because they could not use their weak upper extremity to interact with the virtual objects. We also noted that all the participants had difficulty restricting their movements to the coronal plane, the only plane in which the virtual objects respond; rather, they primarily moved their hands in front of their body (ie, in the sagittal plane). Only one of the five participants in the subacute group aged 59 years and with considerable active movement in his left weak arm appeared to benefit from these environments.

The performance of the participants with acute stroke varied from that of the participants with chronic stroke. During the Wishy-Washy game, some participants with subacute stroke held a towel in their hand, a prop that appeared to help them perform the task of cleaning windows. Moreover, during the Kung-Foo game, their onscreen avatar was eliminated very quickly, causing the game to terminate; this took 18–30 seconds for the first game, 12–45 seconds for the second game, and 36–48 seconds for the third game. For this reason, some participants succeeded in repelling only a few virtual enemies.

Overall, the EyeToy was found to be feasible for individuals with acute and chronic stroke. The individuals with chronic stroke who were generally higher functioning seemed to benefit from the EyeToy more than the individuals with acute stroke. The performance of the participants with stroke was also compared with that of the healthy young and older adults to assess the sensitivity of the system; the results of this comparison are discussed below.

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A high sense of presence and enjoyment was reported by all healthy young and older adults as well as individuals after stroke who used the EyeToy gaming system. The young adults who also experienced the more costly IREX did not perceive differences in the sense of presence between these two systems. These findings are encouraging because a high sense of presence is thought to influence one's performance in a virtual environment. A high level of enjoyment, as reported by all the participants, can also lead to higher motivation to engage in an activity as well as influence performance.17

Any rehabilitation tool must generate outcomes that are sensitive to changes in performance to be useful clinically.41 The EyeToy was found to be sensitive to differences in performance of younger vs older adults and especially between people with and without a disability. The differences were found in both environments (Wishy-Washy and Kung-Foo) and were likely due to variations in the motor ability of the upper extremity, the ability to maintain sitting balance or visuoperceptual abilities (Table 3).

The restricted ability to grade the level of difficulty of the EyeToy applications emphasized a key limitation when it is used with individuals with stroke who are still engaged in subacute rehabilitation. We observed that the EyeToy encouraged nonisolated movements of the upper extremity and trunk especially for individuals with a moderate motor impairment. These movements can be corrected by a therapist located in the virtual environment with or behind the client, providing support and handling. However, this may limit its use by more severely involved clients. Indeed, some of the individuals with moderate hemiparesis who were in subacute rehabilitation expressed frustration especially when they could not manage to interact with the EyeToy environments with their weaker hand. In contrast to our experience, Yavuzer et al,33 who used the EyeToy to train upper extremity movements of 10 subjects with acute stroke, did not report a similar limitation. This difference may be because the subjects in the current study experienced the EyeToy during a single session, whereas the subjects in the latter study practiced these upper extremity movements using the EyeToy for a total of 20 sessions. They may have learned to cope with the game requirements or their functional level may have been higher.

Therapists are able to compensate for the some of the EyeToy's limitations by adjusting the physical setting to make the games easier to play. For example, a client can be positioned closer to the camera (to make movement have a greater effect) or to the side (to encourage different movements patterns) to meet different therapeutic goals. In addition, the client may be provided with physical guidance or help. This was not done during their one-time experience in the current study to maintain consistency between participants.

Another limitation of the EyeToy is the lack of any systematic recording of users' performance (beyond a minimal monitoring of scores). This makes it difficult to track improvement or deterioration within the VR system.

Despite these limitations, the EyeToy appears to have potential as a means to promote exercise for high-functioning individuals with stroke. This is an important consideration because exercise is often boring and hard to maintain, especially when done alone at home.8 A survey conducted by Shaughnessy et al42 on 315 people with stroke reported that only 31% of this sample exercised regularly (ie, at least four times a week). The use of music42,43 and gaming factors during exercise, such as in the EyeToy games, are factors that appear to make a major contribution toward enhancing enjoyment and motivation14 and therefore facilitate participation in regular exercise. This observation was supported by Lotan et al,32 who used the EyeToy to improve the physical fitness of adults with intellectual and developmental disability and by Flynn et al,6 who reported the experience of a woman with stroke who used the EyeToy for intervention at home. The woman reported that using the EyeToy was enjoyable and motivating, which helped her maintain an exercise program at home.

Participation in and maintenance of regular exercise has been recognized as one of the most important health behaviors in preventing and reducing the severity of many chronic diseases.44 Physical exercise is particularly important for older adults and for people who have restricted motor function such as occurs after a stroke.7 Reduced activity can lead to disuse atrophy and cardiovascular deconditioning. This can cause loss in the functional gains achieved during rehabilitation and lead to further deterioration of the person's physical condition.42 As is the case for all video-capture VR systems, the different EyeToy applications encourage the vigorous use of active movement of the upper extremities and trunk while the user is engaged in an enjoyable and motivating activity. In addition, the levels of exertion reported by the participants using the EyeToy fell within the light to somewhat hard exertion levels, which are the recommended levels of exertion for self-paced exercise.45 Although the duration of the experience in the present study was short, it still points to the suitability of the EyeToy as a medium for promoting and facilitating physical rehabilitation and activity.

Home-based rehabilitation after stroke is becoming a more commonly suggested solution to the problem of insufficient inpatient care and one that may facilitate the maintenance and even improvement of the patient's physical health status.46 Because of its low cost and technical simplicity, the EyeToy could be used to sustain a person's continued level of activity in his or her own home after being discharged from rehabilitation. The findings from this study indicate ease of use for older adults. Future studies should determine whether the use of the EyeToy at home is indeed sustainable by both individuals after stroke and their spouses.

In summary, the assets of the low-cost EyeToy for stroke rehabilitation, supported by the results of all three studies, are that it is easy to operate, is enjoyable, and generates a high sense of presence. Differences in participant performance and responses to the tested EyeToy applications suggest that therapists would be able to target diverse clinical objectives. These attributes are valuable in an intervention tool during the rehabilitation of individuals with stroke.

Nevertheless, given its limitations as indicated above, it is important to continue to search for other low-cost VR tools or gaming consoles. These tools need to be technically easy to use, be readily graded in difficulty, and provide a systematic report of performance. Certain products have become available in recent years (eg, by Intel and Reality Fusion) but are no longer marketed. Others, such as TheraGame,29 have just been developed and are in the initial testing stage. GestureTek Health is now in the process of simplifying their system to avoid the reliance on chroma key technology (Ron Kelusky, personal communication). Recently, the Nintendo Wii gaming system ( has also begun to be used in rehabilitation. The Wii is controlled by a client's movement while holding and using a remote control. Preliminary work is currently being done to assess its potential use for the rehabilitation of adults and children, and the results are encouraging.47,48 Future research should aim to test the utility of such low-cost VR systems as well as additional EyeToy games and other video-capture systems for intervention on a larger number of participants who have suffered a stroke.

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The authors gratefully thank Soraya Basha Abu-Rukan for her skillful help with data collection and the third year students in the Department of Occupational Therapy at the University of Haifa. A special thanks to Dr. Gottlieb, who was the first to bring the idea of using the Sony PlayStation 2 EyeToy for rehabilitation to our attention. The authors are grateful to the University of Haifa development fund and the Bollag Foundation for financial support.

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stroke rehabilitation; virtual reality; projected video-capture; low-cost system

© 2008 Neurology Section, APTA