Related Experiment Videos
Memory representations underlying motor commands used during manipulation of common and novel objects
A M Gordon1, G Westling, K J Cole
1Department of Physiology, University of Umeå, Sweden.
Journal of Neurophysiology
|June 1, 1993
Summary
Humans can predict object weight using prior knowledge and visual cues, adjusting grip and lifting forces quickly with practice. This study investigated the motor control strategies for lifting objects of varying densities and weights.
Area of Science:
- Motor Control
- Human Factors Engineering
- Biomechanics
Background:
- Accurate prediction of object weight is crucial for effective manipulation.
- Previous research suggests reliance on prior experience and visual cues for force scaling.
Purpose of the Study:
- To investigate how individuals scale vertical lifting and grip forces based on object properties.
- To determine the role of prior knowledge and practice in adapting to novel object weights and densities.
Main Methods:
- Subjects lifted various objects, with isometric vertical lifting force measured using strain gauge transducers.
- Novel objects with adjustable mass (300g or 1000g) and varying densities were used to assess adaptation.
- Force-rate profiles and loading phase duration were analyzed across multiple lifts.
Main Results:
- Force output was scaled using memory-based information of common object weights, with minimal changes across consecutive lifts.
- Initial lifts of high-density objects showed under-estimation of force, but rapid adaptation occurred within a few trials.
- Adaptation included a significant reduction in the loading phase duration and targeted force-rate profiles.
Conclusions:
- Humans effectively utilize prior knowledge and visual identification to predict and scale lifting forces.
- The motor system demonstrates rapid adaptation to unexpected object weights and densities through practice.
- This research provides insights into the predictive mechanisms underlying human object manipulation.