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Frequency dependence of the action-perception cycle for postural control in a moving visual environment: relative
T M Dijkstra1, G Schöner, M A Giese
1Laboratory of Medical Physics and Biophysics, University of Nijmegen, The Netherlands.
Biological Cybernetics
|January 1, 1994
Summary
Human postural sway remains significant even when visual motion coherence is lost. This active, rhythmic movement is dynamically coupled to visual stimuli, demonstrating relative coordination.
Area of Science:
- Human movement science
- Neuroscience
- Biomechanics
Background:
- Human postural sway is influenced by visual environments.
- The relationship between visual motion and postural control is complex.
- Understanding the dynamics of the action-perception cycle is crucial for human stability.
Purpose of the Study:
- To investigate the temporal relationship between visual motion and postural sway in standing humans.
- To analyze how frequency affects the coherence between visual input and postural sway.
- To explore the underlying mechanisms of postural control during dynamic visual stimulation.
Main Methods:
- Human subjects were exposed to an oscillatory visual display with varying frequencies.
- The temporal relationship (phase) between visual motion and postural sway was analyzed.
- Results were quantitatively compared with a dynamical model (sine-circle map).
Main Results:
- Significant postural sway amplitudes were maintained even when temporal coherence with visual motion was lost.
- Postural sway exhibited phase leading below 0.2 Hz and phase lagging above 0.3 Hz.
- Variable phase relationships and phase jumps were observed, indicative of relative coordination.
Conclusions:
- Postural sway in response to moving visual environments is actively generated rhythmic movement.
- The observed phenomena can be explained by instabilities in the action-perception cycle, not passive driving.
- This suggests a dynamic coupling between visual motion and active postural control mechanisms.