This protocol describes how to use frame-by-frame video analysis to quantify idiosyncratic reach-to-grasp movements in humans. A comparative analysis of reaching in sighted versus unsighted healthy adults is used to demonstrate the technique, but the method can also be applied to the study of developmental and clinical populations.
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Method Article
Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans
In This Article
Summary
Abstract
Prehension, the act of reaching to grasp an object, is central to the human experience. We use it to feed ourselves, groom ourselves, and manipulate objects and tools in our environment. Such behaviors are impaired by many sensorimotor disorders, yet our current understanding of their neural control is far from complete. Current technologies for investigating human reach-to-grasp movements often utilize motion tracking systems that can be expensive, require the attachment of markers or sensors to the hands, impede natural movement and sensory feedback, and provide kinematic output that can be difficult to interpret. While generally effective for studying the stereotypical reach-to-grasp movements of healthy sighted adults, many of these technologies face additional limitations when attempting to study the unpredictable and idiosyncratic reach-to-grasp movements of young infants, unsighted adults, and patients with neurological disorders. Thus, we present a novel, inexpensive, and highly reliable yet flexible protocol for quantifying the temporal and kinematic structure of idiosyncratic reach-to-grasp movements in humans. High speed video cameras capture multiple views of the reach-to-grasp movement. Frame-by-frame video analysis is then used to document the timing and magnitude of pre-defined behavioral events such as movement start, collection, maximum height, peak aperture, first contact, and final grasp. The temporal structure of the movement is reconstructed by documenting the relative frame number of each event while the kinematic structure of the hand is quantified using the ruler or measure function in photo editing software to calibrate 2 dimensional linear distances between two body parts or between a body part and the target. Frame-by-frame video analysis can provide a quantitative and comprehensive description of idiosyncratic reach-to-grasp movements and will enable researchers to expand their area of investigation to include a greater range of naturalistic prehensile behaviors, guided by a wider variety of sensory modalities, in both healthy and clinical populations.
Introduction
Prehension, the act of reaching to grasp an object, is used for many daily functions including acquiring food items for eating, grooming, manipulating objects, wielding tools, and communicating through gesture and written word. The most prominent theory concerning the neurobehavioral control of prehension, the Dual Visuomotor Channel theory1,2,3,4, proposes that prehension consists of two movements - a reach that transports the hand to the location of the target and a grasp that opens, shapes, and closes the hand to the size and shape of the....
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Protocol
All procedures involving human participants have been approved by the University of Lethbridge Human Subjects Research Committee and the Thompson Rivers University Research Ethics for Human Subjects Board.
1. Participants
- Attain informed consent of adults that have normal or corrected-to-normal vision and are of good health with no history of neurological or sensorimotor disorders (unless the aim is to investigate a particular clinical population).
2. Experimental Setup
- Select blueberries, donut balls, and orange slices to serve as reaching targets. Measure a subset of ten of each o....
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Results
This section provides examples of the results that can be obtained when using frame-by-frame video analysis to investigate idiosyncratic reach-to-grasp movements under nonvisual sensory guidance. The primary finding is that when participants can use vision to preemptively identify both the extrinsic (location/orientation) and intrinsic (size/shape) properties of a target object they integrate the reach and the grasp into a single seamless prehensile act in which they preshape the hand to .......
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Discussion
The present paper describes how to use frame-by-frame video analysis to quantify the temporal organization, kinematic structure, and a subset of topographical features of human reach-to-grasp movements. The technique can be used to study typical visually-guided reach-to-grasp movements, but also idiosyncratic reach-to-grasp movements. Such movements are difficult to study using traditional 3D motion tracking systems, but are common in developing infants, participants with altered sensory processing, and patients with sen.......
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Disclosures
The authors have no competing financial interests to disclose.
Acknowledgements
The authors would like to thank Alexis M. Wilson and Marisa E. Bertoli for their assistance with filming and preparing the video for this manuscript. This research was supported by the Natural Sciences and Engineering Research Council of Canada (JMK, JRK, IQW), Alberta Innovates-Health Solutions (JMK), and the Canadian Institutes of Health Research (IQW).
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| High Speed Video Cameras | Casio | http://www.casio-intl.com/asia-mea/en/dc/ex_f1/ or http://www.casio-intl.com/asia-mea/en/dc/ex_100/ | Casio EX-F1 High Speed Camera or Casio EX-100 High Speed Camera used to collect high speed video records |
| Adobe Photoshop | Adobe | http://www.adobe.com/ca/products/photoshop.html | Software used to calibrate and measure distances on individual video frames |
| Adobe Premiere Pro | Adobe | http://www.adobe.com/ca/products/premiere.html?sdid=KKQOM&mv=search&s_kwcid=AL!3085!3!193588412847!e!!g!!adobe%20premiere%20pro&ef_id=WDd17AAABAeTD6-D:20170606160204:s | Software used to perform Frame-by-Frame Video Analysis |
| Height-Adjustable Pedestal | Sanus | http://www.sanus.com/en_US/products/speaker-stands/htb3/ | A height adjustable speaker stand with a custom made 9 cm x 9 cm x 9 cm triangular top plate attached to the top with a screw is used as a reaching pedestal |
| 1 cm Calibration Cube | Learning Resources (Walmart) | https://www.walmart.com/ip/Learning-Resources-Centimeter-Cubes-Set-500/24886372 | A 1 cm plastic cube is used to transform distance measures from pixels to centimeters |
| Studio Light | Dot Line | https://www.bhphotovideo.com/c/product/1035910-REG/dot_line_rs_5620_1600w_led_light.html | Strong lamp with cool LED light used to illumate the participant and testing area |
| 3 Dimensional (3D) Sleep Mask | Kfine | https://www.amazon.com/Kfine-Sleeping-Contoured-lightweight-Comfortable/dp/B06W5CDY78?th=1 | Used as a blindfold to occlude vision in the No Vision condition |
| Orange Slices | N/A | N/A | Orange slices served as the large sized reaching targets |
| Donut Balls | Tim Hortons | http://www.timhortons.com/ca/en/menu/timbits.php | Old fashion plain timbits from Tim Hortons served as the medium sized reaching targets |
| Blueberries | N/A | N/A | Blueberries served as the small sized reaching targets |
References
- Karl, J. M., Whishaw, I. Q. Different evolutionary origins for the Reach and the Grasp: an explanation for dual visuomotor channels in primate parietofrontal cortex. Front Neurol. 4 (208), (2013).
- Whishaw, I. Q., Karl, J. M.
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