Stability of force perception in finger force production tasks
Open Access
- Author:
- Cuadra Gonzalez, Cristian Javier
- Graduate Program:
- Kinesiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 16, 2020
- Committee Members:
- Mark Latash, Dissertation Advisor/Co-Advisor
Mark Latash, Committee Chair/Co-Chair
Robert L Sainburg, Committee Member
Jonas Rubenson, Committee Member
Rick Owen Gilmore, Outside Member
Jonathan Bates Dingwell, Program Head/Chair - Keywords:
- iso-perceptual manifold
uncontrolled manifold
force perception
referent coordinate
psychophysics
kinesthetic perception
sense of effort
back-coupling
motor control
muscle vibration
force drift
force matching - Abstract:
- Despite the agreement on the dual nature of motor actions, where afferent and efferent neural signals interact to produce coordinated movements, the extent to which these two processes generate stable percepts is largely unknown. A new theoretical framework of kinesthesia has been introduced to account for stability of perception within high-dimensional afferent-efferent spaces: the concept of iso-perceptual manifold (IPM). The major goal of this dissertation is to explore predictions under the IPM concept using finger pressing tasks, where stability of force perception is quantified using: 1) force-matching tasks between the two hands; and 2) verbal reports of finger forces. A series of five studies tested predictions of force perception according to the IPM concept. The first study tests the prediction that the task-level salient variable (sum of finger forces) would show more precise and accurate finger force estimation compared to the perception of the outputs of elements contributing to that salient variable (individual finger forces). The second study explores the estimation of finger forces in a range of force magnitudes using force matching tasks and verbal scores, where both quantification methods were expected to show similar trends. The third study examines the extent to which muscle coactivation affects force production and perception. In particular, this study - based on the ideas of motor control with spatial referent coordinates – tests the prediction that, during muscle coactivation, subjects would produce unintentional force increase and be unaware of it. In the last study, the phenomenon of kinesthetic force illusions produced by muscle vibration is characterized in the space of forces. Taken together, this series of studies suggest that percepts of finger forces can vary without affecting the accuracy of perception of total force if this variability is confined to the IPM for total force perception. The discrepancy in force perception between the two methods of percept quantification (verbal scores vs. force matching), suggests that these approaches potentially reflect different neural mechanisms contributing to estimates of perception. Finally, there are consistent force illusion mediated by muscle vibration, supporting the idea that in the multidimensional afferent-efferent space, signals are abundant and muscle spindle activity contributes to force perception.