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Development and empirical assessment of a model of situation awareness for multitasking with locomotion.

作者:Mohamed Ashraf Ali Sheik Nainar,
畢業學校:NCSU
出版單位:NCSU
核准日期:2007-01-19
類型:Electronic Thesis or Dissertation
權限:unrestricted.I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my th....

英文摘要

Human locomotion has long been considered an overly practiced motor behavior.
However, recent research has revealed a demand of locomotion on attentional resources,
especially when performed during multitasking. Situation Awareness (SA), a cognitive
construct critical to decision making and performance in complex tasks, has been shown
to be important while multitasking with cognitive and physical workloads. No research
has been conducted on the role of SA during locomotion with perturbations (e.g., slips
and trips) and concurrent cognitive task performance (e.g., walking and talking on cell
phone).
The primary objective of this research was to develop a model of SA for multitasking
with locomotion to conduct an empirical study to assess the validity of the proposed
model for explaining proactive gait control in response to locomotion hazards. To
support the empirical work, a virtual reality locomotion interface (VRLI) was developed to
present walkers with realistic virtual locomotion environments (VLE) similar to everyday
locomotion activities. An initial version of the VRLI consisted of a computer controlled
treadmill, a head mounted display (HMD), and a graphical workstation running the VLEs
and controlling the treadmill, based on participant movement using motion tracking
sensors. The VRLI setup was validated through a pilot study that compared overground
walking with treadmill walking in a VLE. Results showed similarities in walking
characteristics between the conditions. Based on the pilot study, further enhancements
were made to the setup. These included using a rear projection screen with a stereo
projector and light-shutter goggles and a new treadmill with an embedded force plate
(under the belt) for collecting gait ground reaction forces (GRF) and center of pressure
(COP) data.
Using the enhanced VRLI, an experiment was conducted to evaluate the utility of SA
during locomotion and validate the proposed model of SA for proactive gait control for
responding to locomotion hazards. In this experiment, the controlled variables included
navigation aid type (NT), a priori knowledge (AK) and perturbation cueing (PC). NT
consisted of two levels map-based navigation (MBN) and instruction-based navigation
(IBN) and was manipulated between-subjects. AK consisted of three levels, low, medium
and high, and was also manipulated between-subjects. The AK manipulation involved
controlled the initial exposure of the walker to the test VLE and hence controlled their
mental model development on the task environment. The low AK group was trained with
a low fidelity VLE and medium AK and high AK groups were trained with a high-fidelity
VLE, but only the latter group experienced a perturbation. The PC variable was
manipulated within-subjects and it consisted of combinations of visual cueing and physical
cueing of locomotion hazards forming four levels visual only, physical only, visual plus
physical and no cueing. Dependent variables measured included a battery of GRF and
COP variables along with response accuracy to SA probes presented using a real-time
probing technique. Twelve males and twelve females from the NCSU student population
participated in the experiment and performed the navigation task following four different
routes in the VLE.
Results revealed participant proactive preparation for locomotion hazards, as observed
through significant changes in GRF and COP measures. Effects included the nature of
cueing of the perturbation and prior exposure to a trial with a perturbation involving visual
cueing. There was also a complex interaction between NT, AK and PC that revealed
greater participant proactive control during MBN with higher AK under visual plus
physical cueing compared to IBN with lower AK under visual only cueing. SA accuracy
under MBN was higher for probes requiring subjects to project VLE future states, as
compared to IBN.
Analysis of correlations between SA performance and gait response measures in five
steps leading up to participants encountering perturbations revealed a negative relationship
between SA and weight acceptance (at heel strike) with each step closer to the
perturbation. The correlation was also significantly affected by the manipulated variables
(list variables here in parentheses) and their higher order interactions. The study revealed
that higher SA performance was associated with greater proactive control (decreased
weight acceptance flat footed walking). The results provided preliminary empirical
validation of the proposed model of SA for multitasking with locomotion. Further
experimental studies need to be conducted for a more fine grained investigation of the
relationship of SA with specific proactive gait control mechanisms (e.g., accommodating,
avoiding) under multitasking situations.


chair - David Kaber

chair - Simon Hsiang

committee_member - Gary Mirka

committee_member - Jason Osborne


 

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