Information Technology Reference
In-Depth Information
Figure 10.15.
Installation carried out for the direction search experiment:
the underground passage of train station was figured in the corridor of our laboratory
In two cases (static screens that only display the departing train on their
platform, or dynamic screens that display personalized information), we wish to
study the movement made by users to find their platform, according to the different
possible starting points. As in the previous experiments, we filmed
6
the
experimentations so as to later “segment” the movements of users; see Figure 10.16.
During this segmentation, we identified two kinds of elementary movements:
- advance from platform Q1 to platform
Q
2
. We denote this movement
Q
1
→
Q
2
.
Example:
A
→
B
; and
-turn around at platform A. We denote this movement
Q
.
Example: C
.
These two types of elementary movements enable the trajectory of users to be
described completely. It seems much more relevant to us to carry out such a
segmentation than to measure the time taken by users to reach their destination
platform, as this time can depend on how fast the user moves, which is not a
relevant parameter for our study. Indeed, we do not want the measurements to be
distorted by the subjects walking relatively quickly. In each experiment, the users
had to search for the platform for the train to Lyon, starting from one of the three
landmarks 0, 1 and 2. Once they had found it, they needed to stop in front of the
corresponding screen and raise their hand. For the utilization of results, we first of
all introduce the notion of the
length
of a path. The length of a path is equal to the
number of elementary movements on this path. We can then define the
relative
length
of the path traveled by a user as being equal to the ratio of the length
L
U
of
the path actually traveled by the user by the length
L
O
of the optimal path
7
. For
example, let us assume that the user goes from landmark 1 to platform B. The
optimal path is:
1 → C, C → B
6 The camera was situated at the observation position marked O in Figure 10.15.
7 The
optimal path
is that which has the fewest elementary movements.
