Abstract
The ability of an agent to accomplish a trajectory during a certain motor task depends on the fit between external (environment) and internal (agent) constraints, also known as affordance. A model of difficulty for a generalized reaching motor task is proposed as an affordance-related measure, as perceived by a specific agent for a given environment and task. By extending the information-based Index of Difficulty of a trajectory, a stochastic model of difficulty is formulated based on the observed variability of spatial trajectories executed by a given agent during a repetitive motor task. The model is tested on an experimental walking dataset available in the literature, where the repetitive stride movement of differently aged subjects (14 “old” subjects aged 50-73; 20 “young” subjects aged 21-37) at multiple speed conditions (comfortable, ~30% faster, ~30% slower) is analyzed. Reduced trajectory variability in older as compared to younger adults results in a higher Index of Difficulty (slower: +24%, p < 0.0125; faster: +38%, p < 0.002) which is interpreted in this context as reduced affordance. The model overcomes the limits of existing difficulty measures by capturing the stochastic dependency of task difficulty on a subject’s age and average speed. This model provides a benchmarking tool for motor performance in biomechanics and ergonomics applications.
Original language | English (US) |
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Article number | 4330 |
Journal | Applied Sciences (Switzerland) |
Volume | 11 |
Issue number | 10 |
DOIs | |
State | Published - May 2 2021 |
All Science Journal Classification (ASJC) codes
- General Materials Science
- Instrumentation
- General Engineering
- Process Chemistry and Technology
- Computer Science Applications
- Fluid Flow and Transfer Processes
Keywords
- Affordance
- Foot trajectory
- Gait variability
- Index of difficulty
- Reaching motor task
- Trajectory complexity
- Young and elderly gait