Immediate versus prolonged visual exposure and object relevancy in a reaching and placing task.

This study investigated whether prolonged exposure of objects with varying levels of meaning changes the quality of movement based upon the length of time the object is viewed. Fifty-nine male and female volunteers aged 18 to 45 years participated in this study that involved reaching for and placing a cup or a clay mass in an immediate or a prolonged exposure condition. It was hypothesized that better performance would occur when reaching for the cup than when reaching for the mold of clay. Additionally, there would be a difference in performance depending on whether participants experience the immediate or prolonged exposure of the objects. The results showed that movement time was significantly shorter and there were fewer movement units during the prolonged condition. There were also significant interactions between visual exposure and object relevancy for both percentage of movement time to peak velocity and average velocity. Conversely, there were no differences between the two objects for any of the dependent variables. This study suggests that if a person is allowed prolonged visual exposure to an object in a reaching and placing task his or her movement will be more efficient. This implies that occupational therapists should implement functional tasks and allow adequate time for the person to visually process occupational forms in order to facilitate enhanced quality of movement. Introduction A central concept in occupational therapy involves the use of meaningful objects in order to enhance occupational performance. Occupational therapists strive to choose the right occupations that appropriately challenge their clients’ functional abilities in the most effective manner possible. A common strategy is to choose occupations in which the client finds meaning. Nelson defined meaning as “the person’s entire interpretive process when encountering an occupational form, including perceptual, symbolic, and affective experience”[1]. Several studies have suggested that when a patient engages in an occupational form that has meaning and purpose, his or her motor performance tends to improve. [2-4]. Having a purpose can also influence the patient’s performance. Nelson [1] defined purpose as “the experience of wanting an outcome from an anticipated occupational performance. ” Meaning and purpose can not be directly measured, however they can be inferred through observation and feedback from the patients themselves. The assumption that meaning and purpose are inferred is foundational to what the profession of occupational therapy is based upon. It is the responsibility of the occupational therapist to enhance meaning and purpose to the occupation. A person may perceive an object and though he or she may recognize the object, he or she may not ascribe meaning to the object. One of the assumptions in occupational therapy is that a person will perform better or with Al Ameen J Med. Sci, Volume 2, No.1, 2009 Rice MS . et al ©2009. Al Ameen Charitable Fund Trust, Bangalore 23 more enthusiasm if an object holds meaning. For example, a study by Kircher [5] recruited individuals who had expressed a prior interest in jumping rope. The participants involved were 26 women between the ages of 19 to 37 years. The task involved two exercises of jumping rope (purposeful activity) and jumping in place (nonpurposeful activity). The results showed that the participants’ heart rates increased at a given rate of perceived exertion and were significantly higher in the jumping rope condition. The results supported the concept that in a non-meaningful occupation, the workload was perceived by the participants to be greater. A study by Hsieh, Nelson, Smith, and Peterson [6], investigated whether giving participants added-purpose occupations would elicit more exercise repetitions. Participants included 21 subjects with hemiplegia between the ages of 51-78 years. Each participant was to complete the three conditions of a dynamic standing balance exercise. This exercise involved bending down, reaching, standing up, and extending the arm. The three conditions included the added purpose, the imaging, and the control conditions. The task involved the target being placed 4m in front of the subject and with small balls placed on the ground near the unimpaired leg. The subjects picked the small balls up and tossed as many as they could for as long as they could to the target. The participants completed significantly more repetitions in the added-materials condition and in the imagery-based condition than in the rote exercise. These results support the concept that when occupational forms are occupationally embedded the performance that is elicited is of a higher level than when the occupational forms are not occupationally embedded. Ferguson and Trombly [2] investigated the effects of both added-purpose and meaningful occupation on motor learning. Participants were assigned to an added-purpose or a rote exercise condition. The task in the added-purpose condition required participants to practice three separate five-note patterns to produce a musical tune. The rote condition required the participants to practice the same patterns as in the addedpurpose condition. The rote condition was meant only for learning purposes of a motor pattern without tone production. Participants in the rote exercise condition practiced the same three five-note patterns for the purpose of learning a motor pattern with production of a tune. Specifically the results were that the added-purpose condition demonstrated a significantly greater performance in motor learning. The results supported the concept that having an added-purpose can enhance performance in terms of permanent aspects, such as motor learning. Some studies suggest that the more contextually relevant the occupational forms are to the occupation, the better the occupational performance will be. For example, Ferguson and Rice [7] investigated whether practicing a complex self-care occupation in a contextually relevant environment would enhance the learning and transfer of skill. The participants included 56 college-aged women with a mean age of approximately 25 years. They were separated into either the contextually relevant group or the noncontextually relevant group. The task involved the contextually relevant group practicing tying a rope onto a pole using the style of knot as in the contextually relevant condition, which was practicing tying a necktie onto a mannequin. The results were that there was no difference in the rate of performance change during the acquisition phase between the contextually relevant and the non-contextually Al Ameen J Med. Sci, Volume 2, No.1, 2009 Rice MS . et al ©2009. Al Ameen Charitable Fund Trust, Bangalore 24 relevant groups. There was a significant difference in the rate of performance change among the three groups in movement time and movement units during the transfer phase. The results supported the concept that practicing an occupation in a contextually relevant environment would influence the learning and transfer of a motor skill. Ma, Trombly, and Robinson-Podolski [8] investigated the effect of context on skill acquisition and transfer. The participants included 12 male and 28 female college students without disabilities. The task involved using chopsticks in either a natural or a simulated context. In the acquisition phase participants in the natural condition picked up pieces of cheese with metal chopsticks and placed the cheese in a dish. In the simulated condition, participants picked up small pieces of eraser. In the transfer phase the participants used wooden chopsticks and picked up shell-shaped pasta noodles to eat. The results were that the natural context elicited significantly greater success during the acquisition phase, as well as significantly greater success during the transfer phase compared to the participants in the simulated context. No differences were found in kinematic variables between the two contexts. The results supported the concept of using natural contexts to facilitate the outcome of motor skill learning. Wu, Trombly and Lin [4] investigated whether reaching performance would show an enhanced quality of movement in a materials-based occupation (picking up a pencil and preparing to write their name) compared to both an imagery based occupation (imagining picking up a pencil and preparing to write their name) and in exercise (rote reaching pattern). The participants included 37 female college students. This study explored kinematic variables of reaction time, movement time, number of movement units, and amplitude of peak velocity and percentage of movement time at which peak velocity occurred. The materials based condition involved having the participants pick up a pencil from a pencil holder and prepare to write their name. In the imagery-based occupation they picked up the pencil from a point in space and in the exercise condition they performed a movement of reaching forward. The results were that the materials-based occupation elicited an enhanced quality of movement performance as compared to the imagery-based and exercise conditions. The results supported the concept that material-based occupations might be useful in eliciting an enhanced quality of reaching movement. Gasser-Wieland and Rice [9], investigated the effects of enhanced occupational embeddedness on upper extremity movement dynamics. Participants included 17 survivors of cerebral vascular accident (CVA). The experiment involved two conditions including the occupational embedded (labeled soup cans) and nonoccupationally embedded (clay masses) conditions. Participants were to move their assigned objects (either the soup cans or clay masses) from a kitchen counter to the cabinet with each limb. The results were that the occupational embedded condition demonstrated significantly fewer movement units and smaller movement times. The results supported the theory that greater occup