Limits...
Haptic-motor transformations for the control of finger position.

Shibata D, Choi JY, Laitano JC, Santello M - PLoS ONE (2013)

Bottom Line: We hypothesized that matching error (reference hand dy minus test hand dy ) would be greater (a) for collinear than non-collinear dy s, (b) when reference and test hand postures were not congruent, and (c) when subjects reproduced dy using the opposite hand.Our results confirmed our hypotheses.These findings indicate that perceived finger pad distance is reproduced less accurately (1) with the opposite than the same hand and (2) when higher-level processing of the somatosensory feedback is required for non-congruent hand postures.

View Article: PubMed Central - PubMed

Affiliation: Kinesiology Program, College of Health Solutions, Arizona State University, Tempe, Arizona, United States of America.

ABSTRACT
Dexterous manipulation relies on modulation of digit forces as a function of digit placement. However, little is known about the sense of position of the vertical distance between finger pads relative to each other. We quantified subjects' ability to match perceived vertical distance between the thumb and index finger pads (dy ) of the right hand ("reference" hand) using the same or opposite hand ("test" hand) after a 10-second delay without vision of the hands. The reference hand digits were passively placed non-collinearly so that the thumb was higher or lower than the index finger (dy  = 30 or -30 mm, respectively) or collinearly (dy  = 0 mm). Subjects reproduced reference hand dy by using a congruent or inverse test hand posture while exerting negligible digit forces onto a handle. We hypothesized that matching error (reference hand dy minus test hand dy ) would be greater (a) for collinear than non-collinear dy s, (b) when reference and test hand postures were not congruent, and (c) when subjects reproduced dy using the opposite hand. Our results confirmed our hypotheses. Under-estimation errors were produced when the postures of reference and test hand were not congruent, and when test hand was the opposite hand. These findings indicate that perceived finger pad distance is reproduced less accurately (1) with the opposite than the same hand and (2) when higher-level processing of the somatosensory feedback is required for non-congruent hand postures. We propose that erroneous sensing of finger pad distance, if not compensated for during contact and onset of manipulation, might lead to manipulation performance errors as digit forces have to be modulated to perceived digit placement.

Show MeSH

Related in: MedlinePlus

Absolute error: average data.Absolute errors were compared across reference hand dys, postures, hands, and matching conditions. Panel A shows average absolute error for symmetric and asymmetric conditions (black and gray bars, respectively) across reference hand dys. Panel B, left, shows average absolute error for symmetric and asymmetric conditions (black and gray bars, respectively) as a function of hand posture (Sym, Asym: Symmetric and Asymmetric conditions, respectively). Panel B, right, shows average absolute error when reference and test hand differed or were the same (Oppo, Same: Opposite and Same conditions, respectively). Panel C shows absolute error averaged for each condition. For all panels, absolute errors were averaged across all subjects within the given comparisons groups (±SE). The asterisks denote significant difference (p<0.05) between the symmetric and asymmetric conditions.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3675141&req=5

pone-0066140-g004: Absolute error: average data.Absolute errors were compared across reference hand dys, postures, hands, and matching conditions. Panel A shows average absolute error for symmetric and asymmetric conditions (black and gray bars, respectively) across reference hand dys. Panel B, left, shows average absolute error for symmetric and asymmetric conditions (black and gray bars, respectively) as a function of hand posture (Sym, Asym: Symmetric and Asymmetric conditions, respectively). Panel B, right, shows average absolute error when reference and test hand differed or were the same (Oppo, Same: Opposite and Same conditions, respectively). Panel C shows absolute error averaged for each condition. For all panels, absolute errors were averaged across all subjects within the given comparisons groups (±SE). The asterisks denote significant difference (p<0.05) between the symmetric and asymmetric conditions.

Mentions: Greater absolute error in the collinear than non-collinear dy was observed in both symmetric and asymmetric matching conditions (black and gray bars, Fig. 4A). Three-way ANOVA confirmed that absolute error was significantly greater in the collinear than non-collinear conditions (12.6±0.9 mm for dy = 0 mm; 9.0±0.9 mm for dy = −30 mm; 8.8±0.7 for dy = 30 mm; main effect of Distance: F[2,28] = 10.8; p<0.01; Fig. 4A), and in the asymmetric than symmetric condition (12.0 ±0.9 mm and 8.3±0.5 mm, respectively; main effect of Posture: F[1,14] = 26.5; p<0.01; Fig. 4B, left). We also found a significant interaction Posture × Distance (7.1±0.8 mm for Symmetric at dy = −30 mm; 9.6±1.0 mm for Symmetric at dy = 0 mm; 8.1±0.7 mm for Symmetric at dy = 30 mm; 10.8±1.1 mm for Asymmetric at dy = −30 mm; 15.5±1.4 mm for Asymmetric at dy = 0 mm; 9.6±1.0 mm for Asymmetric at dy = 30 mm; F[2,28] = 4.02; p<0.05; Fig. 4A).


Haptic-motor transformations for the control of finger position.

Shibata D, Choi JY, Laitano JC, Santello M - PLoS ONE (2013)

Absolute error: average data.Absolute errors were compared across reference hand dys, postures, hands, and matching conditions. Panel A shows average absolute error for symmetric and asymmetric conditions (black and gray bars, respectively) across reference hand dys. Panel B, left, shows average absolute error for symmetric and asymmetric conditions (black and gray bars, respectively) as a function of hand posture (Sym, Asym: Symmetric and Asymmetric conditions, respectively). Panel B, right, shows average absolute error when reference and test hand differed or were the same (Oppo, Same: Opposite and Same conditions, respectively). Panel C shows absolute error averaged for each condition. For all panels, absolute errors were averaged across all subjects within the given comparisons groups (±SE). The asterisks denote significant difference (p<0.05) between the symmetric and asymmetric conditions.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3675141&req=5

pone-0066140-g004: Absolute error: average data.Absolute errors were compared across reference hand dys, postures, hands, and matching conditions. Panel A shows average absolute error for symmetric and asymmetric conditions (black and gray bars, respectively) across reference hand dys. Panel B, left, shows average absolute error for symmetric and asymmetric conditions (black and gray bars, respectively) as a function of hand posture (Sym, Asym: Symmetric and Asymmetric conditions, respectively). Panel B, right, shows average absolute error when reference and test hand differed or were the same (Oppo, Same: Opposite and Same conditions, respectively). Panel C shows absolute error averaged for each condition. For all panels, absolute errors were averaged across all subjects within the given comparisons groups (±SE). The asterisks denote significant difference (p<0.05) between the symmetric and asymmetric conditions.
Mentions: Greater absolute error in the collinear than non-collinear dy was observed in both symmetric and asymmetric matching conditions (black and gray bars, Fig. 4A). Three-way ANOVA confirmed that absolute error was significantly greater in the collinear than non-collinear conditions (12.6±0.9 mm for dy = 0 mm; 9.0±0.9 mm for dy = −30 mm; 8.8±0.7 for dy = 30 mm; main effect of Distance: F[2,28] = 10.8; p<0.01; Fig. 4A), and in the asymmetric than symmetric condition (12.0 ±0.9 mm and 8.3±0.5 mm, respectively; main effect of Posture: F[1,14] = 26.5; p<0.01; Fig. 4B, left). We also found a significant interaction Posture × Distance (7.1±0.8 mm for Symmetric at dy = −30 mm; 9.6±1.0 mm for Symmetric at dy = 0 mm; 8.1±0.7 mm for Symmetric at dy = 30 mm; 10.8±1.1 mm for Asymmetric at dy = −30 mm; 15.5±1.4 mm for Asymmetric at dy = 0 mm; 9.6±1.0 mm for Asymmetric at dy = 30 mm; F[2,28] = 4.02; p<0.05; Fig. 4A).

Bottom Line: We hypothesized that matching error (reference hand dy minus test hand dy ) would be greater (a) for collinear than non-collinear dy s, (b) when reference and test hand postures were not congruent, and (c) when subjects reproduced dy using the opposite hand.Our results confirmed our hypotheses.These findings indicate that perceived finger pad distance is reproduced less accurately (1) with the opposite than the same hand and (2) when higher-level processing of the somatosensory feedback is required for non-congruent hand postures.

View Article: PubMed Central - PubMed

Affiliation: Kinesiology Program, College of Health Solutions, Arizona State University, Tempe, Arizona, United States of America.

ABSTRACT
Dexterous manipulation relies on modulation of digit forces as a function of digit placement. However, little is known about the sense of position of the vertical distance between finger pads relative to each other. We quantified subjects' ability to match perceived vertical distance between the thumb and index finger pads (dy ) of the right hand ("reference" hand) using the same or opposite hand ("test" hand) after a 10-second delay without vision of the hands. The reference hand digits were passively placed non-collinearly so that the thumb was higher or lower than the index finger (dy  = 30 or -30 mm, respectively) or collinearly (dy  = 0 mm). Subjects reproduced reference hand dy by using a congruent or inverse test hand posture while exerting negligible digit forces onto a handle. We hypothesized that matching error (reference hand dy minus test hand dy ) would be greater (a) for collinear than non-collinear dy s, (b) when reference and test hand postures were not congruent, and (c) when subjects reproduced dy using the opposite hand. Our results confirmed our hypotheses. Under-estimation errors were produced when the postures of reference and test hand were not congruent, and when test hand was the opposite hand. These findings indicate that perceived finger pad distance is reproduced less accurately (1) with the opposite than the same hand and (2) when higher-level processing of the somatosensory feedback is required for non-congruent hand postures. We propose that erroneous sensing of finger pad distance, if not compensated for during contact and onset of manipulation, might lead to manipulation performance errors as digit forces have to be modulated to perceived digit placement.

Show MeSH
Related in: MedlinePlus