Shannon Lim | University of British Columbia (original) (raw)
Papers by Shannon Lim
Journal of rehabilitation medicine, Jan 15, 2015
It is important for older adults to be physically active, but many older adults walk slowly. This... more It is important for older adults to be physically active, but many older adults walk slowly. This study examined the accuracy of a commercially available step-count device (Fitbit One) at slow speeds and compared the accuracy of the device when worn at the ankle and waist in older adults. The Fitbit One was placed at the ankle and waist of participants (n=42; mean age 73 years) while they performed walking trials at 7 different speeds (0.3-0.9 m/s). Step counts obtained from video recordings were used as the gold standard comparison to determine the accuracy of the device. The ankle-worn device had significantly less error than the waist-worn device at all speeds. The percentage error of the ankle-worn device was less than 10% at speeds of 0.4-0.9 m/s and did not record zero steps at any speed. The percentage error of the waist-worn device was below 10% at only the 2 fastest speeds (0.8 and 0.9 m/s) and recorded zero steps for numerous participants at speeds of 0.3-0.5 m/s. The Fitb...
Physical therapy, Jan 6, 2015
As physical activity in individuals post-stroke is low, devices that monitor and provide feedback... more As physical activity in individuals post-stroke is low, devices that monitor and provide feedback of walking activity provide motivation to engage in exercise and may assist rehabilitation professionals in auditing walking activity. However, most feedback devices are not accurate at slow walking speeds. This study assessed the accuracy of one accelerometer, the Fitbit One, to measure walking steps of community-dwelling individuals post-stroke. Cross-sectional study METHODS: Two accelerometers were positioned on the non-paretic waist and ankle of participants (n=43) and walking steps from these devices were recorded from seven speeds (0.3-0.9m/s) and compared to video recordings (gold standard). When positioned at the waist, the accelerometer had more than 10% error at all speeds, except 0.8 and 0.9m/s, and numerous participants recorded zero steps at 0.3-0.5m/s. The device had 10% or less error when positioned at the ankle for all speeds between 0.4-0.9m/s. Some participants were un...
Journal of motor behavior, 2014
There is evidence that the learning benefits of contextual interference (CI) are moderated by exp... more There is evidence that the learning benefits of contextual interference (CI) are moderated by experience, yet we do not know if these experiences are related to specific practice with random schedules. In two experiments, CI practice schedule was manipulated on Day 1. We evaluated its impact on 3 new tasks on Day 2; in the same or different practice schedule (Experiment 1) or when participants chose their practice (Experiment 2). Typical CI effects were observed for both sets of tasks, although on Day 2, there were no longer any costs from random practice. Previous practice affected how practice was scheduled. The prior random group switched more than the prior blocked group. Although switching was related to retention, overall the groups did not differ. Therefore, specific experiences with a method of practice influence later choices about how to practice, performance in practice, but not necessarily what is retained.
Experimental Brain Research, 2014
Observers can learn to move in novel, adapted environments after watching a learning or expert mo... more Observers can learn to move in novel, adapted environments after watching a learning or expert model. Although this is an effective practice technique, it is unclear how this learning is achieved and if observers update an internal model of their visual-motor environment, as shown through the presence of after-effects (i.e., negative carry-over effects when aiming in a normal environment following exposure to perturbed conditions). For such updating to occur via observational practice, it has been reasoned that the observer requires the motor capabilities to perform the task they are observing. To test this, we first trained three groups to physically move in clockwise (CW) or counterclockwise (CCW) rotated environments. When immediately returned to a normal environment, after-effects were seen. We then attempted to wash out these effects before allowing two of these groups (CW and CCW), and a naïve observation only group, to watch a video of an actor performing in a CW environment. This observation phase was immediately followed by another test for after-effects and a direct test of learning when aiming in the rotated environment. Consistent with previous data, there were direct learning effects due to observation. Although after-effects increased for the experienced observers, these were small and were not significantly different from a physical practice only group that did not undergo the observation phase. Therefore, even with a motor repertoire for the rotated environment, there was a lack of evidence that observational practice results in implicit (re)updating of an internal model for aiming.
BIO Web of Conferences, 2011
We review data from 4 experiments where we have been studying what is learnt through observation.... more We review data from 4 experiments where we have been studying what is learnt through observation. In these experiments people learnt to reach in a distorted visual-motor, virtual environment. In all experiments observers successfully adapted to new visual-motor environments just by watching. Importantly, however, they adapted differently to actors. At no time did naïve observers show after-effects when returned to a known normal environment. However, if observers had previously practiced in this environment, after-effects were subsequently seen following an observation phase. Further, again different to actors, they showed good retention and lack of interference when performing in two opposing environments. We argue that observation does not result in the updating of an internal (motor) model, that it is primarily strategically mediated and that only after physical experience in the environment can 'motor-simulation' through observation take place.
Journal of rehabilitation medicine, Jan 15, 2015
It is important for older adults to be physically active, but many older adults walk slowly. This... more It is important for older adults to be physically active, but many older adults walk slowly. This study examined the accuracy of a commercially available step-count device (Fitbit One) at slow speeds and compared the accuracy of the device when worn at the ankle and waist in older adults. The Fitbit One was placed at the ankle and waist of participants (n=42; mean age 73 years) while they performed walking trials at 7 different speeds (0.3-0.9 m/s). Step counts obtained from video recordings were used as the gold standard comparison to determine the accuracy of the device. The ankle-worn device had significantly less error than the waist-worn device at all speeds. The percentage error of the ankle-worn device was less than 10% at speeds of 0.4-0.9 m/s and did not record zero steps at any speed. The percentage error of the waist-worn device was below 10% at only the 2 fastest speeds (0.8 and 0.9 m/s) and recorded zero steps for numerous participants at speeds of 0.3-0.5 m/s. The Fitb...
Physical therapy, Jan 6, 2015
As physical activity in individuals post-stroke is low, devices that monitor and provide feedback... more As physical activity in individuals post-stroke is low, devices that monitor and provide feedback of walking activity provide motivation to engage in exercise and may assist rehabilitation professionals in auditing walking activity. However, most feedback devices are not accurate at slow walking speeds. This study assessed the accuracy of one accelerometer, the Fitbit One, to measure walking steps of community-dwelling individuals post-stroke. Cross-sectional study METHODS: Two accelerometers were positioned on the non-paretic waist and ankle of participants (n=43) and walking steps from these devices were recorded from seven speeds (0.3-0.9m/s) and compared to video recordings (gold standard). When positioned at the waist, the accelerometer had more than 10% error at all speeds, except 0.8 and 0.9m/s, and numerous participants recorded zero steps at 0.3-0.5m/s. The device had 10% or less error when positioned at the ankle for all speeds between 0.4-0.9m/s. Some participants were un...
Journal of motor behavior, 2014
There is evidence that the learning benefits of contextual interference (CI) are moderated by exp... more There is evidence that the learning benefits of contextual interference (CI) are moderated by experience, yet we do not know if these experiences are related to specific practice with random schedules. In two experiments, CI practice schedule was manipulated on Day 1. We evaluated its impact on 3 new tasks on Day 2; in the same or different practice schedule (Experiment 1) or when participants chose their practice (Experiment 2). Typical CI effects were observed for both sets of tasks, although on Day 2, there were no longer any costs from random practice. Previous practice affected how practice was scheduled. The prior random group switched more than the prior blocked group. Although switching was related to retention, overall the groups did not differ. Therefore, specific experiences with a method of practice influence later choices about how to practice, performance in practice, but not necessarily what is retained.
Experimental Brain Research, 2014
Observers can learn to move in novel, adapted environments after watching a learning or expert mo... more Observers can learn to move in novel, adapted environments after watching a learning or expert model. Although this is an effective practice technique, it is unclear how this learning is achieved and if observers update an internal model of their visual-motor environment, as shown through the presence of after-effects (i.e., negative carry-over effects when aiming in a normal environment following exposure to perturbed conditions). For such updating to occur via observational practice, it has been reasoned that the observer requires the motor capabilities to perform the task they are observing. To test this, we first trained three groups to physically move in clockwise (CW) or counterclockwise (CCW) rotated environments. When immediately returned to a normal environment, after-effects were seen. We then attempted to wash out these effects before allowing two of these groups (CW and CCW), and a naïve observation only group, to watch a video of an actor performing in a CW environment. This observation phase was immediately followed by another test for after-effects and a direct test of learning when aiming in the rotated environment. Consistent with previous data, there were direct learning effects due to observation. Although after-effects increased for the experienced observers, these were small and were not significantly different from a physical practice only group that did not undergo the observation phase. Therefore, even with a motor repertoire for the rotated environment, there was a lack of evidence that observational practice results in implicit (re)updating of an internal model for aiming.
BIO Web of Conferences, 2011
We review data from 4 experiments where we have been studying what is learnt through observation.... more We review data from 4 experiments where we have been studying what is learnt through observation. In these experiments people learnt to reach in a distorted visual-motor, virtual environment. In all experiments observers successfully adapted to new visual-motor environments just by watching. Importantly, however, they adapted differently to actors. At no time did naïve observers show after-effects when returned to a known normal environment. However, if observers had previously practiced in this environment, after-effects were subsequently seen following an observation phase. Further, again different to actors, they showed good retention and lack of interference when performing in two opposing environments. We argue that observation does not result in the updating of an internal (motor) model, that it is primarily strategically mediated and that only after physical experience in the environment can 'motor-simulation' through observation take place.