Accurate perception and control of self-motion is vital for human survival. Most
animals rely on vision for navigating through complex environments. In this
thesis, I investigated how vision influence perception and guide self-motion
from two aspects: (1) what visual information humans pick up from the
environment to form their perception and guide their self-motion; (2) how the
degeneration of the basal ganglia and cerebellum, the two largest subcortical
nuclei connecting the visual and motor areas of the brain, affect the controller’s
performance.
Study 1 examined the condition under which optic-flow information
beyond velocity field helps heading perception. I systematically varied the
amount of information in velocity field through manipulations of field of view
(FOV). The amount of optic-flow information beyond velocity field was
manipulated by two types of displays. I found heading bias increased with the
reduction of FOV only when optic-flow information beyond velocity field was
not available.
Study 2 investigated whether the information investigated in Study 1 is
sufficient and necessary for active control of heading. I used the similar display
simulations as study 1 with the exception that the vehicle orientation was
perturbed pseudo-randomly. Participants used a joystick, under both velocity
and acceleration control dynamics, to continuously rotate the vehicle orientation
back to its heading direction. The results showed that participants’ accurate
performance under condition that only provided velocity field information was
further improved when optic-flow information beyond velocity field was
available.
Study 3 examined the relative contributions of three visual cues (i.e.,
heading from optic flow, bearing, and splay angle) for lane-keeping control.
Observers controlled the car’s lateral movement to stay in the center of the lane
while facing two random perturbations affecting the use of bearing or splay
angle information. I found that performance improved with enriched flow
information. In the presence of splay angles, participants ignored bearing angle
information.
Study 4 investigated the roles of the basal ganglia and cerebellum in
motor control task using brain-damaged patients. Participant’s task was to use
the joystick to keep a blob in the center of the display while the horizontal
position of the blob was perturbed pseudo-randomly. This task is not a
self-motion task but mimics real-world lane-keeping control. Both the
Parkinson’s disease patients and cerebellar patients showed impaired motor
control performance in comparison with the healthy controls.
In conclusion, the visual information used for motor control in general
depends on the task. For traveling along a curved path, the velocity field
contains sufficient information for heading perception and heading control.
Optic-flow information beyond velocity field improves heading perception
when the velocity field does not contain sufficient information. It also helps
heading control when available. For lane-keeping control, adding optic flow
information improves participants’ performance. Splay angle information plays
a more important role than does bearing angle information. The visual
information used for motor control changes when certain brain areas are
damaged. Parkinson’s disease patients and cerebellar patients show the inability
to process visual input effectively for online motor control. / published_or_final_version / Psychology / Doctoral / Doctor of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174516 |
| Date | January 2012 |
| Creators | Chen, Jing, 陈静 |
| Contributors | Li, L, Hayward, WG |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47849587 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
Page generated in 0.0023 seconds