Problem: Designing the user experience is a growing trend in product design; however this
trend has not greatly benefited people with impairments and disabilities. There are no practical
tools to broadly assist with this issue. There is a need for standardized measures to quantify
impairment, a model to predict how designs may perform and a need for data regarding how
people with impairments interact with consumer technology.
Purpose: To conduct a usability analysis with an industry partner on their powered wheelchair
controller using participants with varying impairments. The industry partner was seeking
better insight into the benefits of formal user testing.
Method: Forty consenting adults were given a score representing their level of impairment
using six measures from the International Classification of Functioning (ICF). These measures
were identified by the researcher to affect interaction with a device. Performance was
measured by time taken to complete tasks, errors made, reported task difficulty and reported
controller usability.
Results: Performance was reduced in participants with a higher ICF score and age. An ICF score
less than or equal to 2 was 117 times more likely to not complete the tasks, greater than or
equal to 3 was not able to complete the experiment. Age >50 years took an average 79 seconds
longer than <35 years to complete a task and reported greater difficulty, more errors and a
lower usability for the controller.
Implications: Low to moderate levels of impairment has a significantly negative effect on the
usability of common devices. Difficulties were mostly cognitive with participants unable to
create an accurate mental model of the system. Participants with lower performance tended to
be overly optimistic about their abilities. Mistakes were the greatest source of error followed by
lapses and almost no reported or observed slip errors.
Original Contribution: The ICF has never been used as a metric for usability testing. This study
successfully applied the ICF alongside other measures to prove its validity. Based on the results
and current literature the Task Process Model was created to provide a simple and practical
way to describe the interaction of people completing a task of basic to moderate complexity.
| Identifer | oai:union.ndltd.org:canterbury.ac.nz/oai:ir.canterbury.ac.nz:10092/10412 |
| Date | January 2015 |
| Creators | Horne, Rory Michael |
| Publisher | University of Canterbury. Mechanical Engineering |
| Source Sets | University of Canterbury |
| Language | English |
| Detected Language | English |
| Type | Electronic thesis or dissertation, Text |
| Rights | Copyright Rory Michael Horne, http://library.canterbury.ac.nz/thesis/etheses_copyright.shtml |
| Relation | NZCU |
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