Spatial Knowledge Acquisition in the Context of GPS-Based Pedestrian Navigation - Maps for the Future Children Education and Internet - page 131

The development of the voice-based prototype was based on the semantic-based
model developed in the previous project SemWay (Rehrl et al. 2010 ). Based on the
model, semantic-based route instructions instead of metric-based route instructions
can be provided, for example, “walk straight, pass the theatre, and walk to the
crossing” instead of “walk straight for 103 m”. Verbal instructions for each decision
point of the test route were automatically generated by using the semantic-based
model (Rehrl et al. 2010 ). The interface of the voice-based prototype includes a
single screen with a slider for controlling the sound volume and a button for
repeating the last instruction. When a user gets close to a decision point, the mobile
device vibrates, and plays the voice instruction describing the actions from this
decision point to the next.
11.2.3 Design and Procedure
Participants were randomly divided into three groups. A within subject design and a
counterbalancing consideration were used for the test, i.e., for each sub-route, these
three groups each used one of the navigation prototypes (mobilemap-based, AR-based,
and voice-based). When they reached the next sub-route, they switched to another
prototype. Each participant was accompanied by two researchers. One observed the test
run and guided through the interviews and the other collected quantitative and qualita-
tive performance measures (e.g., the number of stops, duration of stops, and reasons of
stops). Participants' movement, interaction with the navigation prototypes, task com-
pletion time, and GPS accuracy were also logged on mobile phones.
At the beginning of the test session, we explained the basic usage of the
pedestrian navigation prototypes to the participants and gave a short demonstration
of the prototypes on the mobile phones. After a brief training session, participants
were led to the starting point of the first sub-route. The task for them was to navigate
to the end of the sub-route. If participants decided wrongly at a decision point, the
observing researcher used gestures to indicate the correct choice. No other assis-
tance was given during navigation. In order to avoid any influence on participants,
the researchers walked several metres behind participants. When reaching the end
of the sub-route, participants were asked to answer questionnaires assessing usabil-
ity and task load, and to give some further qualitative feedback and experiences. In
addition, they were asked to solve some tasks assessing spatial knowledge
acquisition:
• Pointing task: to give an approximate direction to the starting point of the current
sub-route, measured in degrees via a digital compass on mobile phones;
• Sketching map: to draw a sketch map of the area they just passed as precisely as
possible, focusing on the route and landmarks;
• Marking task: to mark the half of the sub-route on their sketch maps;
• To indicate their familiarity with the current sub-route before the test.