The influence of naturalistic materials on motor learning for assistive device use in adults with arthritis

Motor learning is an important aspect of occupational therapy, especially as it relates to learning the fine motor skills necessary to use a novel tool or assistive device in order to maximize independence. The present study aimed to assess the influence of occupational embeddedness on motor learning of a fine motor task involving a novel tool. The influence of the human mirror-neuron system on rate of motor learning, specifically action-observation (AO) and verbal instruction (V), was also analyzed and results are described in a separate study. It was hypothesized that rate of motor learning would be significantly greater in the occupationally embedded (OE) condition than in the non-occupationally embedded, or rote (R), condition. Twenty-six male and female adults with arthritis were recruited for this study and were randomly assigned to the OE and R conditions. The task involved using ergonomically modified pliers to pick up small objects and sort them into a divided container using either naturalistic or simulated materials. Kinematic data was analyzed for the dependent variables of movement time, average velocity, movement displacement, and movement units. Statistical significance was found for the repeated factor of trial, but not between the OE and R conditions except for the variable of displacement. A significant interaction was also found between the four groups in favor of AO/OE and V/R conditions. Our results suggest that occupational embeddedness alone does not significantly increase the rate of fine motor learning. Based on our results, pairing OE with AO or R with V can result in significantly improved rates of fine motor learning pertaining to the use of a tool or assistive device. This translates to the fundamental necessity of effectively manipulating occupational forms to elicit the best motor performance and subsequent therapeutic benefits. NATURALISTIC MATERIALS AND MOTOR LEARNING 3 Introduction At the core of occupational therapy is the use of objects and tasks meaningful to the client to encourage increased occupational performance. It is the role of the occupational therapist to create environments that elicit meaning and subsequent purpose for an individual which also challenge one’s functional competencies with an appropriate level of difficulty in order for progress to be made. Meaning can be defined as “the person’s entire interpretive process when encountering an occupational form, including perceptual, symbolic, and affective experience” (Nelson, 1996, p. 776). The functional abilities and characteristics of the client in combination with the environment surrounding the occupation at hand may facilitate the perception of meaning which is unique to that individual. To enhance one’s occupational performance, it is not enough for the occupational therapist to create only meaning for the client, as purpose must then be brought forth. Purpose is one’s motivation to do something, or as Nelson (1996, p. 777) describes, “. the experience of wanting an outcome from an anticipated occupational performance. ” Meaning must be first established before purpose can be formed. It is also important to note that even if something is perceived as meaningful for a certain person, he or she may or may not generate purpose, or in other words, be motivated to elicit a particular outcome. It is important for the occupational therapist to construct environments that will both facilitate the perception of meaning for an individual and subsequently generate a sense of purpose towards the situation. The literature supports the use of purposeful occupations over those which are nonpurposeful. Hsieh, Nelson, Smith, and Peterson (1996) studied whether adding purpose in a dynamic standing balance exercise would lead to more repetitions than rote exercise alone in clients with hemiplegia. Three conditions were established, materials-based, imagery-based, and NATURALISTIC MATERIALS AND MOTOR LEARNING 4 rote exercise. In the materials-based condition, subjects bent down, picked up a small ball from the ground with their unimpaired hand, stood back up, and threw the ball at a target. The imagery-based condition required performing this same movement pattern while imaging picking up and throwing the ball, while the rote condition involved only performing the movement pattern. The results of this study show a significant increase in the number of repetitions completed in the materialsand imagery-based conditions compared with rote exercise. The authors thus concluded that adding purpose to therapeutic occupations can lead to enhanced performance. Bakshi, Bhambhani, and Madill (1991) conducted a study in which healthy females participated in a most-preferred and least preferred task, each under a purposeful and nonpurposeful condition. For example, one of the tasks that could be chosen was painting. This modality was considered purposeful if the subject had actual paint, brushes, and a canvas with which to create a finished product; this was considered to be less meaningful if there were no materials or end product and the client repetitively moved the arm similar to as if he or she was actually painting. Subjects chose two tasks to engage in from a list of eight options, one being their most preferred and the other their least preferred. They engaged in each task under purposeful and non-purposeful conditions. Heart rate, blood pressure, repetitions, and rating of perceived exertion were measured under each of the four conditions. The number of repetitions was found to be lower during the purposeful condition for both the least preferred and most preferred tasks, but the difference was not significant. However, increase in heart rate and ratings of perceived exertion were significantly higher for the non-purposeful activity. Based on these results, the authors concluded that physiological and perceived stress is higher while NATURALISTIC MATERIALS AND MOTOR LEARNING 5 participating in non-purposeful activity, thus suggesting using purposeful tasks in therapy to decrease this stress. Keh-chung, Lin et al. (1997) conducted a meta-analysis of over fifty articles and abstracts which studied a relationship proposed by Nelson (1988) in which participation in purposeful activity produced better quality of movement compared to focusing on movement itself. Three typologies of environmental conditions were incorporated into studies included in this analysis. These were materials-based occupation, imagery-based occupation, and rote exercise. Conventional and process-oriented measures were conducted. Conventional outcome measures included range and duration of movements and the number of repetitions. Process-oriented measures included smoothness of movement, reaction and movement times, velocity, and displacement. Results of the analysis showed a relationship between occupational form and performance, thereby supporting the hypothesis that occupationally embedded tasks lead to enhanced motor performance in comparison with rote exercise. This effect was true for both materials-based and imagery-based occupational forms. Larger effects were found for the process-oriented measures, suggesting that the type of occupational form had a greater impact on the quality of one’s movement compared to conventional measures. Furthermore, it has been shown that conditions with added purpose can specifically enhance motor learning. Wu, Trombly, and Lin (1994) found that participants who performed a reaching task (picking up a pencil in preparation to write one’s name) under a materials-based condition performed with higher quality of movement than those in imagery-based and exercise conditions. Kinematic variables analyzed included reaction time, movement time, number of movement units, and total displacement among others. NATURALISTIC MATERIALS AND MOTOR LEARNING 6 Yuen, Nelson, Peterson, and Dickinson (1993) found that those who were trained to use an above-elbow training prosthesis in an added-materials method scored significantly better on a tracing test compared to those in the control group. Fifty-two college-aged males were randomly assigned to either an added-purpose group or control group. In each group, a flashlight was attached to a farmer’s hook at the distal end of the prosthesis. The added-materials group was trained to use the prosthesis by practicing connecting dots on the wall in front of them with the light beam as accurately as possible. Those in the control group were simply asked to move the forearm component of prosthesis however they could while trying to be as steady as possible. In this condition, the flashlight was fixed to the prosthesis in a non-functional way (toward the hook of the prosthesis) to ensure equal weight in each condition. Both groups then completed a tracing task, where it was found that the added-material’s group deviated from the line significantly less compared to the control group, demonstrating better motor learning of use of the prosthesis. Ferguson and Trombly (1996) conducted a study to test skill acquisition under purposeful and non-purposeful conditions. All participants (healthy university students) were taught three five-note sequences on a keyboard. In the added-purpose condition, musical notes were produced when the participant would press the keys on the device when performing the sequence, while those in the rote exercise condition performed the same movement pattern without the production of sound. All participants were given time to practice all three sequences in multiple acquisition trials, a thirty minute rest period, and then were tested for recall of the skill in several retention trials. Transfer of skill was tested as subjects in both groups were asked to play a new five-note tune. Number of errors was measured for each participant, defined by inaccurate finger placement on the keys and inaccurate sequencing of keys. Although there was no significant difference in the number of