Miller Robotic Interface II Bedienungsanleitung PDF herunterladen (Seite 21)

3 TESTING METHODOLOGY

Because it is important to quantify situation awareness (SA), we discuss SA measurement

techniques here. Again, situation awareness, with respect to this research, is defined as “the

understanding that the human has of the location, activities, status and surroundings of the

robot. Further, [it is also] the understanding of the certainty with which the human knows the

aforementioned information.” [Drury et al. 2003]

The tests that were conducted during the creation of this interface, as well as the previous

studies of other systems, followed the same basic testing format. Each study was geared at

assessing SA to figure out what was the best interface or system. Hjelmfelt and Pokrant [1998]

state that experimental methods for measuring SA fall into three categories:

Subjective: Subjects rate their own SA.

Implicit performance: Experimenters measure task performance, assuming that a subject’s

performance correlates with SA and that improved SA will lead to improved

performance.

Explicit performance: Experimenters directly probe the subject’s SA by asking questions

during short suspensions of the task.

For these studies, we could have used the most popular method, Endsley’s [1988] Situation

Awareness Global Assessment Technique (SAGAT), which falls under the explicit category.

However, we did not feel it was appropriate to use a method that relied upon stopping the user’s

progress to inquire about their SA. These interruptions can cause adverse effects on the user’s

ability to maintain the concentration needed to perform well at the task. Instead we elected to

use mainly implicit measures to associate task outcomes with implied SA. The implicit measures

we used were task completion time as well as the number of collisions. A faster completion time

as well as fewer collisions implies better SA. We did perform an explicit measure at the end of

some studies, where the user was asked to complete a secondary task. Subjective methods of

measuring SA are known to be very unreliable, so we do not depend on any subjective methods

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Miller Robotic Interface II Bedienungsanleitung Seite 21