Page 375 - Sensing, Intelligence, Motion : How Robots and Humans Move in an Unstructured World

350 HUMAN PERFORMANCE IN MOTION PLANNING

is done by the underlying software. Both the labyrinth test (Figure 7.1)
and the arm test (Figure 7.5) are done in this version.
2. In this test, called the physical test, the subject works in the booth,
moving the physical arm (Figure 7.10). Only the arm tests, and no
labyrinth tests, were done in this version.
C. Visibility factor, with two levels:
1. Visible environment: The object (one of those in factor A) and its envi-
ronment are fully visible.
2. Invisible environment: Obstacles cannot be seen by the subject, except
when the robot (in case of the point robot) or a part of its body (in case
of the arm) is close enough to an obstacle, in which case a small part
of the obstacle near the contact point becomes visible for the duration
of contact. The arm is visible at all times.
D. Direction factor (for the arm manipulator test only), with two levels:
1. “Left-to-right” motion (denoted below LtoR), as in Figure 7.8.
2. “Right-to-left” motion (denoted RtoL); in Figure 7.8 this would corre-
spond to moving the arm from position T to position S.
E. Training factor. The goal here is to study the effect of prior learning and
practice on human performance. This factor is studied in combination with
all prior factors and has two levels:
1. Subjects’ performance with no prior training. Here the subjects are only
explained the rules and controls, and are given the opportunity to try
and get comfortable with the setup, before the actual test starts.
2. Subjects’ performance is measured after a substantial prior training and
practice.

Therefore, the focus of Experiment One is on factors B, C, and D, and the
focus of Experiment Two is on factor E (with the tests based on the same factors
B, C, and D). Because each factor is a dichotomy with two levels, all possible
combinations of levels for factors B, C, and D produce eight tasks that each
subject can be subjected to:
Task 1: Virtual, visible, left-to-right
Task 2: Virtual, visible, right-to-left
Task 3: Virtual, invisible, left-to-right
Task 4: Virtual, invisible, right-to-left
Task 5: Physical, visible, left-to-right
Task 6: Physical, visible, right-to-left
Task 7: Physical, invisible, left-to-right
Task 8: Physical, invisible, right-to-left

In addition to these tasks, a smaller study was carried out to measure the effect
of three auxiliary variables: