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Distinct haptic cues do not reduce interference when learning to reach in multiple force fields.

Cothros N, Wong J, Gribble PL - PLoS ONE (2008)

Bottom Line: The idea that different haptic cues (e.g. those associated with different grasped objects) signal motor requirements and promote the learning and retention of multiple motor skills has previously been unexplored in the context of force field learning.The present study tested the possibility that interference can be reduced when two different force fields are associated with differently shaped objects grasped in the hand.These results suggest that in the context of the present learning paradigm, haptic cues on their own are not sufficient to reduce interference and promote learning multiple force fields.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, The University of Western Ontario, London, Canada.

ABSTRACT

Background: Previous studies of learning to adapt reaching movements in the presence of novel forces show that learning multiple force fields is prone to interference. Recently it has been suggested that force field learning may reflect learning to manipulate a novel object. Within this theoretical framework, interference in force field learning may be the result of static tactile or haptic cues associated with grasp, which fail to indicate changing dynamic conditions. The idea that different haptic cues (e.g. those associated with different grasped objects) signal motor requirements and promote the learning and retention of multiple motor skills has previously been unexplored in the context of force field learning.

Methodology/principle findings: The present study tested the possibility that interference can be reduced when two different force fields are associated with differently shaped objects grasped in the hand. Human subjects were instructed to guide a cursor to targets while grasping a robotic manipulandum, which applied two opposing velocity-dependent curl fields to the hand. For one group of subjects the manipulandum was fitted with two different handles, one for each force field. No attenuation in interference was observed in these subjects relative to controls who used the same handle for both force fields.

Conclusions/significance: These results suggest that in the context of the present learning paradigm, haptic cues on their own are not sufficient to reduce interference and promote learning multiple force fields.

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Related in: MedlinePlus

Movement perpendicular distance is shown over the course of movements in the CWFF, CCWFF and CWFF.Data plotted in dark grey represent subjects who grasped the same handle in all three sessions. Data plotted in light grey represent subjects who grasped a given handle shape for the CWFF and a different handle shape for the CCWFF. Each data point represents the mean perpendicular distance over 6 movements, averaged over subjects.
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pone-0001990-g002: Movement perpendicular distance is shown over the course of movements in the CWFF, CCWFF and CWFF.Data plotted in dark grey represent subjects who grasped the same handle in all three sessions. Data plotted in light grey represent subjects who grasped a given handle shape for the CWFF and a different handle shape for the CCWFF. Each data point represents the mean perpendicular distance over 6 movements, averaged over subjects.

Mentions: Subjects were randomly assigned to one of two groups. Seven subjects performed the task while the handle of the manipulandum remained the same (a cylindrical handle). For another group of 7 subjects, each force field was associated with a differently shaped handle. The CWFF was transmitted through the cylindrical handle and the CCWFF was transmitted through a spherical handle (see Figure 2). The cylindrical handle was 88 mm tall, 24 mm wide and 84 mm in circumference. These dimensions are in line with those of a previous study using a robotic manipulandum [18]. The spherical handle measured 88 mm in height, 78 mm in width and 250 mm in circumference. Subjects were instructed to use the same grip for both handles, with full contact between the glabrous skin (of the fingers and palm) and the handle. The configuration of the arm was also held constant. To ensure that our results were not due to the particular handle shape, the experiment was repeated using two other groups of subjects, for whom the association between handles and force fields was reversed. Handle shape was counterbalanced in these two groups in order to rule out the possibility that any effects due to handle shape are an idiosyncrasy of the order in which the handles are presented. One group (n = 5) grasped only the spherical handle for all three force fields, and the other group (n = 5) grasped the spherical handle when exposed to the CWFF and the cylindrical handle when exposed to the intervening CCWFF.


Distinct haptic cues do not reduce interference when learning to reach in multiple force fields.

Cothros N, Wong J, Gribble PL - PLoS ONE (2008)

Movement perpendicular distance is shown over the course of movements in the CWFF, CCWFF and CWFF.Data plotted in dark grey represent subjects who grasped the same handle in all three sessions. Data plotted in light grey represent subjects who grasped a given handle shape for the CWFF and a different handle shape for the CCWFF. Each data point represents the mean perpendicular distance over 6 movements, averaged over subjects.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2291555&req=5

pone-0001990-g002: Movement perpendicular distance is shown over the course of movements in the CWFF, CCWFF and CWFF.Data plotted in dark grey represent subjects who grasped the same handle in all three sessions. Data plotted in light grey represent subjects who grasped a given handle shape for the CWFF and a different handle shape for the CCWFF. Each data point represents the mean perpendicular distance over 6 movements, averaged over subjects.
Mentions: Subjects were randomly assigned to one of two groups. Seven subjects performed the task while the handle of the manipulandum remained the same (a cylindrical handle). For another group of 7 subjects, each force field was associated with a differently shaped handle. The CWFF was transmitted through the cylindrical handle and the CCWFF was transmitted through a spherical handle (see Figure 2). The cylindrical handle was 88 mm tall, 24 mm wide and 84 mm in circumference. These dimensions are in line with those of a previous study using a robotic manipulandum [18]. The spherical handle measured 88 mm in height, 78 mm in width and 250 mm in circumference. Subjects were instructed to use the same grip for both handles, with full contact between the glabrous skin (of the fingers and palm) and the handle. The configuration of the arm was also held constant. To ensure that our results were not due to the particular handle shape, the experiment was repeated using two other groups of subjects, for whom the association between handles and force fields was reversed. Handle shape was counterbalanced in these two groups in order to rule out the possibility that any effects due to handle shape are an idiosyncrasy of the order in which the handles are presented. One group (n = 5) grasped only the spherical handle for all three force fields, and the other group (n = 5) grasped the spherical handle when exposed to the CWFF and the cylindrical handle when exposed to the intervening CCWFF.

Bottom Line: The idea that different haptic cues (e.g. those associated with different grasped objects) signal motor requirements and promote the learning and retention of multiple motor skills has previously been unexplored in the context of force field learning.The present study tested the possibility that interference can be reduced when two different force fields are associated with differently shaped objects grasped in the hand.These results suggest that in the context of the present learning paradigm, haptic cues on their own are not sufficient to reduce interference and promote learning multiple force fields.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, The University of Western Ontario, London, Canada.

ABSTRACT

Background: Previous studies of learning to adapt reaching movements in the presence of novel forces show that learning multiple force fields is prone to interference. Recently it has been suggested that force field learning may reflect learning to manipulate a novel object. Within this theoretical framework, interference in force field learning may be the result of static tactile or haptic cues associated with grasp, which fail to indicate changing dynamic conditions. The idea that different haptic cues (e.g. those associated with different grasped objects) signal motor requirements and promote the learning and retention of multiple motor skills has previously been unexplored in the context of force field learning.

Methodology/principle findings: The present study tested the possibility that interference can be reduced when two different force fields are associated with differently shaped objects grasped in the hand. Human subjects were instructed to guide a cursor to targets while grasping a robotic manipulandum, which applied two opposing velocity-dependent curl fields to the hand. For one group of subjects the manipulandum was fitted with two different handles, one for each force field. No attenuation in interference was observed in these subjects relative to controls who used the same handle for both force fields.

Conclusions/significance: These results suggest that in the context of the present learning paradigm, haptic cues on their own are not sufficient to reduce interference and promote learning multiple force fields.

Show MeSH
Related in: MedlinePlus