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Updated: May 24, 2026
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Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans
Published on: January 15, 2018
Target contrast affects reaching and grasping in the visually impaired subjects
Shahina Pardhan1, Carmen Gonzalez-Alvarez, Ahalya Subramanian
1Vision and Eye Research Unit, Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, United Kingdom. shahina.pardhan@anglia.ac.uk
Summary
Individuals with visual impairment (VI) exhibit slower reaching and grasping movements. However, their maximum grip aperture and velocity are comparable to visually normal individuals, suggesting online visual feedback is crucial for VI.
Area of Science:
- Neuroscience
- Ophthalmology
- Biomechanics
Background:
- Central visual impairment (VI) affects motor control.
- Understanding reaching and grasping in VI is crucial for rehabilitation.
Purpose of the Study:
- To compare reaching and grasping behavior in subjects with VI versus normal subjects.
- To investigate the effect of target contrast on motor performance in VI.
Main Methods:
- 14 subjects with VI and 14 age-matched controls performed reaching and grasping tasks.
- Three targets (black, white, transparent) were used against a black background.
- A motion analysis system recorded hand and finger movements.
Main Results:
- Subjects with VI showed significantly longer movement onset and duration.
- No significant differences in maximum grip aperture and velocity were observed.
- Time after maximum grip aperture was longer in subjects with VI.
Conclusions:
- VI subjects require more time to initiate and complete reaching/grasping movements.
- Once visually acquired, target interaction performance is similar between groups.
- Online visual feedback plays a critical role in motor adjustments for individuals with VI.
