Biomedical Engineering Reference
In-Depth Information
performed significantly better than the Vis group, and performance of the Rot group
was clearly intermediate. Ruddle et al. (Expt. 1) [
17
] uses the “worst” and “best”
shading levels because there was a main effect of navigation performance, and pair-
wise comparisons showed that the Full group performed significantly better than
either of the other groups. The Riecke et al. [
12
] data refers to the number of revisits
metric, which is more sensitive than the percentage of perfect trials. There was a
main effect, and pair-wise comparisons indicated that the Full and Rot groups were
equivalent, but there was a marginally significant difference between the Rot and Vis
groups.
Caution should be taken when drawing conclusions from results that were statis-
tically not significant. Sometimes this is due to there being no underlying difference.
On other occasions it is due to a lack of statistical power, and this is particularly true
in navigation studies, which often have large individual differences.
5.4.2 Studies Investigating the Effect of Body-Based Information
5.4.2.1 Single-Route Acquisition and Small-Scale Environments
All three of the studies included in this section [
23
-
25
] used a triangle completion
paradigm (this involved being guided along two legs of a path and then being asked
to point or return directly to the start point, which assesses a participant's ability to
take short cuts). Klatzky et al. reported a step change in performance between Vis
and Rot groups of participants, with the latter performing accurately and the former
not. By contrast, Kearns et al. (Experiments 1 and 3) reported a small but signifi-
cant difference between Vis and Full groups, with the Vis group performing more
accurately. The difference between the studies' findings may be due to participants'
mode of response, because Klatzky's pointed to where they would have to travel to
return to a trial's start point, and the errors were assumed to occur because the Vis
group failed to update their cognitive heading. Kearns' participants' responded by
traveling to where they thought the start point was located, and while doing so may
have corrected their cognitive heading. Some support for this explanation is provided
by subsequent research, which showed that the errors reported by Klatzy et al. did
not occur if participants responded verbally [
33
].
Péruch et al. reported that participants who walked (a Full group) performed best
and thosewhowere in aVis group performedworst, in direct contrast to the findings of
Kearns et al. However, Péruch's study combined responses from triangle completion
trials with responses from trials in which participants had to reverse the two-leg path
that had been traveled. In research by Ruddle et al. [
15
] substantially fewer errors
were made by participants who physically walked and then reversed a path (a Full
group) than participants who were in a Rot group. If a similar difference occurred
in Péruch's study then the Full group's superior performance on path-reversal trials
more than compensated for slightly inferior performance on the triangle completion
trials, and that would explain the difference with Kearns et al's findings.
