Page 395 - Sensing, Intelligence, Motion : How Robots and Humans Move in an Unstructured World

370 HUMAN PERFORMANCE IN MOTION PLANNING

TABLE 7.11. ANOVA Results for Completion Time: Direction, Interface, and
Visibility Factors
ANOVA Effects Studied: 1—interface, 2—visibility, 3—direction
df MS df MS
Effect Effect Effect Error Error F-Value p-Level
1 1 5248143.0 184 51978.68 100.9672 0.000000
2 1 189719.0 184 51978.68 3.6499 0.057626
3 1 3475104.0 184 51978.68 66.8563 0.000000

12 1 12523.0 184 51978.68 0.2409 0.624127
13 1 427953.0 184 51978.68 8.2332 0.005494
23 1 45246.0 184 51978.68 0.8705 0.352049
123 1 52450.0 184 51978.68 1.0091 0.316444

TABLE 7.12. ANOVA Results for Completion Time: Interface and Visibility
Factors, LtoR Task
ANOVA Effects Studied: 1—interface, 2—visibility
df MS df MS
Effect Effect Effect Error Error F-Value p-Level
1 1 1339396.0 92 32864.84 40.75467 0.000000
2 1 210132.0 92 32864.84 6.39382 0.013155
12 1 6858.0 92 32864.84 0.20867 0.648886

Hence the data for the left-to-right task was analyzed, which is one of two
levels of the direction factor. The summary of related ANOVA results appears in
Table 7.12. The p-level for the interface factor is smaller than 0.01, the p-level for
the visibility factor is about 0.01, and the p-level for the interface factor is greater
than 0.01. Therefore, the main effect of interface is statistically significant, the
main effect of visibility is slightly significant, and there is no interaction between
them. This reconciles with our knowledge that for both visible or invisible tasks,
the completion time for the physical task is significantly shorter than for the
virtual task. Similarly, for both physical or virtual tasks the completion time is
slightly shorter in the visible environment than in the invisible environment.
The summary of ANOVA results for the right-to-left task appears in Table 7.13.
The p-level for the interface factor is smaller than 0.01, the p-levels for the vis-
ibility factor and interaction are greater than 0.01. This means the main effect
of the interface factor is statistically significant, and there is no interaction. This