Limits...
Direct comparisons of hand and mouth kinematics during grasping, feeding and fork-feeding actions.

Quinlan DJ, Culham JC - Front Hum Neurosci (2015)

Bottom Line: As in many past studies, we found that the hand oversized considerably larger (~11-27 mm) than the food item during grasping; moreover, the amount of oversizing scaled with food size.Surprisingly, regardless of whether the hand or fork was used to transport the food, the mouth oversized only slightly larger (~4-11 mm) than the food item during biting and the oversizing did not increase with food size.Taken together, our results show that while many aspects of kinematics share some similarity between grasping and feeding, oversizing may reflect strategies unique to the hand vs. mouth (such as the need to have the digits approach the target surface perpendicularly for grip stability during lifting) and differences in the neural substrates of grasping and feeding.

View Article: PubMed Central - PubMed

Affiliation: Brain and Mind Institute, University of Western Ontario London, ON, Canada ; Department of Psychology, Huron University College London, ON, Canada ; Graduate Program in Neuroscience, University of Western Ontario London, ON, Canada.

ABSTRACT
While a plethora of studies have examined the kinematics of human reach-to-grasp actions, few have investigated feeding, another ethologically important real-world action. Two seminal studies concluded that the kinematics of the mouth during feeding are comparable to those of the hand during grasping (Castiello, 1997; Churchill et al., 1999); however, feeding was done with a fork or spoon, not with the hand itself. Here, we directly compared grasping and feeding kinematics under equivalent conditions. Participants were presented with differently sized cubes of cheese (10-, 20- or 30-mm on each side) and asked to use the hand to grasp them or to use a fork to spear them and then bring them to the mouth to bite. We measured the apertures of the hand during grasping and the teeth during feeding, as well as reaching kinematics of the arm in both tasks. As in many past studies, we found that the hand oversized considerably larger (~11-27 mm) than the food item during grasping; moreover, the amount of oversizing scaled with food size. Surprisingly, regardless of whether the hand or fork was used to transport the food, the mouth oversized only slightly larger (~4-11 mm) than the food item during biting and the oversizing did not increase with food size. Total movement times were longer when using the fork compared to the hand, particularly when using the fork to bring food to the mouth. While reach velocity always peaked approximately halfway through the movement, relative to the reach the mouth opened more slowly than the hand, perhaps because less time was required for the smaller oversizing. Taken together, our results show that while many aspects of kinematics share some similarity between grasping and feeding, oversizing may reflect strategies unique to the hand vs. mouth (such as the need to have the digits approach the target surface perpendicularly for grip stability during lifting) and differences in the neural substrates of grasping and feeding.

No MeSH data available.


Related in: MedlinePlus

Grip component results. (A) Averaged aperture profiles (as a function of absolute time, in ms) illustrate that Hand-to-Food, Hand-to-Mouth and Fork-to-Mouth reaches display distinctly different grip patterns. (B) The hand oversizes considerably more than does the mouth, regardless of whether or not a fork was used to transport the food item. Moreover, oversizing scales with object size for the hand but not the mouth. (C) The mouth reaches peak aperture later than does the hand, particularly if a fork was used to transport the food.
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Figure 2: Grip component results. (A) Averaged aperture profiles (as a function of absolute time, in ms) illustrate that Hand-to-Food, Hand-to-Mouth and Fork-to-Mouth reaches display distinctly different grip patterns. (B) The hand oversizes considerably more than does the mouth, regardless of whether or not a fork was used to transport the food item. Moreover, oversizing scales with object size for the hand but not the mouth. (C) The mouth reaches peak aperture later than does the hand, particularly if a fork was used to transport the food.

Mentions: All data and movement profiles for both Experiments 1 and 2 were first analyzed with absolute time (in ms) on the x-axis (rather than relative (%) time, as in some studies; Figures 2A, 2A, 3A). As each movement took a different amount of time to complete (even within the same condition), movement profiles for reach velocity and hand/mouth aperture in each of the experimental conditions needed to be averaged for each participant. To achieve these averaged profiles, the average number of time points it took a given participant to complete the movement of a given condition (Example: Subject A, 10 mm cube, H2F) was calculated. All the movement profiles for that particular condition were then resampled to the average number of time points it took that participant to complete that movement condition. This resampling method ensured that the value of a peak measure and the time at which it occurred were preserved to a greater degree than when trials within a given condition are simply averaged without resampling. This process was repeated for each of the experimental conditions and for each participant. Once this was completed, peak reach velocity, the time of peak reach velocity, aperture oversizing, and the time of peak aperture were extracted from the resampled movement profiles of each participant. These measures, along with total movement time, were then analyzed using a repeated-measures analysis of variance (ANOVA), followed by post hoc, paired-sample t-tests where appropriate. For qualitative comparisons of coordination between transport and grip components for the three conditions in which both transport and grip variables were available (H2F, H2M, F2M), the data were also replotted with the x-axis rescaled to relative (%) movement time and the y-axis (reach velocity for transport component; grip aperture for grip component) rescaled to a percentage of the maximum value (Figure 4).


Direct comparisons of hand and mouth kinematics during grasping, feeding and fork-feeding actions.

Quinlan DJ, Culham JC - Front Hum Neurosci (2015)

Grip component results. (A) Averaged aperture profiles (as a function of absolute time, in ms) illustrate that Hand-to-Food, Hand-to-Mouth and Fork-to-Mouth reaches display distinctly different grip patterns. (B) The hand oversizes considerably more than does the mouth, regardless of whether or not a fork was used to transport the food item. Moreover, oversizing scales with object size for the hand but not the mouth. (C) The mouth reaches peak aperture later than does the hand, particularly if a fork was used to transport the food.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4612668&req=5

Figure 2: Grip component results. (A) Averaged aperture profiles (as a function of absolute time, in ms) illustrate that Hand-to-Food, Hand-to-Mouth and Fork-to-Mouth reaches display distinctly different grip patterns. (B) The hand oversizes considerably more than does the mouth, regardless of whether or not a fork was used to transport the food item. Moreover, oversizing scales with object size for the hand but not the mouth. (C) The mouth reaches peak aperture later than does the hand, particularly if a fork was used to transport the food.
Mentions: All data and movement profiles for both Experiments 1 and 2 were first analyzed with absolute time (in ms) on the x-axis (rather than relative (%) time, as in some studies; Figures 2A, 2A, 3A). As each movement took a different amount of time to complete (even within the same condition), movement profiles for reach velocity and hand/mouth aperture in each of the experimental conditions needed to be averaged for each participant. To achieve these averaged profiles, the average number of time points it took a given participant to complete the movement of a given condition (Example: Subject A, 10 mm cube, H2F) was calculated. All the movement profiles for that particular condition were then resampled to the average number of time points it took that participant to complete that movement condition. This resampling method ensured that the value of a peak measure and the time at which it occurred were preserved to a greater degree than when trials within a given condition are simply averaged without resampling. This process was repeated for each of the experimental conditions and for each participant. Once this was completed, peak reach velocity, the time of peak reach velocity, aperture oversizing, and the time of peak aperture were extracted from the resampled movement profiles of each participant. These measures, along with total movement time, were then analyzed using a repeated-measures analysis of variance (ANOVA), followed by post hoc, paired-sample t-tests where appropriate. For qualitative comparisons of coordination between transport and grip components for the three conditions in which both transport and grip variables were available (H2F, H2M, F2M), the data were also replotted with the x-axis rescaled to relative (%) movement time and the y-axis (reach velocity for transport component; grip aperture for grip component) rescaled to a percentage of the maximum value (Figure 4).

Bottom Line: As in many past studies, we found that the hand oversized considerably larger (~11-27 mm) than the food item during grasping; moreover, the amount of oversizing scaled with food size.Surprisingly, regardless of whether the hand or fork was used to transport the food, the mouth oversized only slightly larger (~4-11 mm) than the food item during biting and the oversizing did not increase with food size.Taken together, our results show that while many aspects of kinematics share some similarity between grasping and feeding, oversizing may reflect strategies unique to the hand vs. mouth (such as the need to have the digits approach the target surface perpendicularly for grip stability during lifting) and differences in the neural substrates of grasping and feeding.

View Article: PubMed Central - PubMed

Affiliation: Brain and Mind Institute, University of Western Ontario London, ON, Canada ; Department of Psychology, Huron University College London, ON, Canada ; Graduate Program in Neuroscience, University of Western Ontario London, ON, Canada.

ABSTRACT
While a plethora of studies have examined the kinematics of human reach-to-grasp actions, few have investigated feeding, another ethologically important real-world action. Two seminal studies concluded that the kinematics of the mouth during feeding are comparable to those of the hand during grasping (Castiello, 1997; Churchill et al., 1999); however, feeding was done with a fork or spoon, not with the hand itself. Here, we directly compared grasping and feeding kinematics under equivalent conditions. Participants were presented with differently sized cubes of cheese (10-, 20- or 30-mm on each side) and asked to use the hand to grasp them or to use a fork to spear them and then bring them to the mouth to bite. We measured the apertures of the hand during grasping and the teeth during feeding, as well as reaching kinematics of the arm in both tasks. As in many past studies, we found that the hand oversized considerably larger (~11-27 mm) than the food item during grasping; moreover, the amount of oversizing scaled with food size. Surprisingly, regardless of whether the hand or fork was used to transport the food, the mouth oversized only slightly larger (~4-11 mm) than the food item during biting and the oversizing did not increase with food size. Total movement times were longer when using the fork compared to the hand, particularly when using the fork to bring food to the mouth. While reach velocity always peaked approximately halfway through the movement, relative to the reach the mouth opened more slowly than the hand, perhaps because less time was required for the smaller oversizing. Taken together, our results show that while many aspects of kinematics share some similarity between grasping and feeding, oversizing may reflect strategies unique to the hand vs. mouth (such as the need to have the digits approach the target surface perpendicularly for grip stability during lifting) and differences in the neural substrates of grasping and feeding.

No MeSH data available.


Related in: MedlinePlus