A study was performed by Santello et al. in 1998 to investigate whether grasping postures showed natural patterns of coordination between the many joints of the human hand. Participants were asked to grasp imaginary objects of diverse shapes with one of their hands. The angles between various segments of the hand were measured with a tracking glove, and analyzed to identify ``postural synergies". This report documents a replication of the 1998 study, using visual tracking of the hand with a wearable headset. The key analysis of interest of the replication is a principal component analysis (PCA) of the joint angles data from grasping of a number of geometries. An important finding of the original paper was that the first two principal components account for more than 80% of the variance in posture.
While a goal of the original experiment was to better understand the neuromuscular basis of movement, its results have proved significant for efficient motion planning in robotic manipulators, as well as for the design and control of prosthetic hands. The choice of this study for replication was motivated by an interest in simplifying the control of prosthetic devices by exploiting an understanding of the neural control of movement.
It was anticipated that the use of visual tracking might lead to less accurate data for fingers which were partially or completely occluded from the camera. Since the stimuli were entirely verbal, it was likely that different subjects would interpret them differently based on their own imagined shape and size of each object. Finally, owing to a lack of experience with implementation, minor challenges were expected in obtaining joint angle data in a usable form from a proprietary headset, and performing a PCA in the chosen computing environment.
Project repository: https://github.com/psych251/santello1998
Original paper: https://github.com/psych251/santello1998/blob/main/original_paper/Santello1998_postural_synergies.pdf
Please describe all the steps necessary to reproduce the key result(s) of this study.
Explicitly describe known differences in the analysis pipeline between the original paper and yours (e.g., computing environment). The goal, of course, is to minimize those differences, but differences may occur. Also, note whether such differences are anticipated to influence your ability to reproduce the original results.
Please describe the outcome measure for the success or failure of your reproduction and how this outcome will be computed.
Earlier in this report, you described the steps necessary to reproduce the key result(s) of this study. Please describe your progress on each of these steps (e.g., data preprocessing, model fitting, model evaluation).
Data preparation following the analysis plan.
The analyses as specified in the analysis plan.
Side-by-side graph with original graph is ideal here
###Exploratory analyses
Any follow-up analyses desired (not required).
Open the discussion section with a paragraph summarizing the primary result from the key analysis and assess whether you successfully reproduced it, partially reproduced it, or failed to reproduce it.
Add open-ended commentary (if any) reflecting (a) insights from follow-up exploratory analysis of the dataset, (b) assessment of the meaning of the successful or unsuccessful reproducibility attempt - e.g., for a failure to reproduce the original findings, are the differences between original and present analyses ones that definitely, plausibly, or are unlikely to have been moderators of the result, and (c) discussion of any objections or challenges raised by the current and original authors about the reproducibility attempt (if you contacted them). None of these need to be long.