Automotive User Interfaces and Interactive Vehicular Applications

• Telephone application
– Call the contact “Staffan”
– Add the contact“Elin”with home number“118118”
• Logistic application
– Ask the system to read the first order
– Show your colleagues on the map
The test leader planned the test so that the participants
started each task at approximately the same spot along the
route. We altered the test conditions so that one third of
the participants began with the SUI condition, one third
with the GUI condition and one third with the multimodal
condition. This was done to minimize the bias from learning
the system during the test so that the last condition is
the easiest to use. Before starting the car, the test leader
presented the tasks and demonstrated the first task (call
the contact “Staffan”) by using the condition that the participant
should start with. Before starting a new condition
the participant was told to stop the car so that the test
leader could demonstrate that condition. The participants
also practised the task while the car was standing still.
5. RESULTS
We wanted to compare ease of use and how the driving ability
changed depending on modality. Task performance was
measured by the test leader on a 4-grade scale:
• Ok without support
– the task was performed without any help from the
test leader
• Ok with light support
– the test leader gave one or two instructions
• Ok with considerable support
– the test leader gave three or more instructions
• Not ok, task is aborted
– the test leader or the participant decided to abort
the task
• Ok with slight mistake
– the task was performed, although there were a
slight misunderstanding of the task. For example,
the participant added the wrong phone number or
called wrong contact. In these cases, the mistakes
were due to wrong input from the participant and
not a misinterpretation from the system.
Driving ability was estimated by the participants. After
each task, the participant was asked to estimate the driving
ability during the task on a 10-grade Likert scale, where 10
meant “My driving ability was equally good as when I drove
without performing any task” and 1 meant “My driving ability
was really bad”.
We also measured task completion time for each task, starting
with the participant pushing the first button to either
start the voice recognition or choose menu on the manual
interface, and ending with the participant returning to the
main menu.
5.1 Task performance
Figure 5.1 shows task performance.
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When using the manual interface, the participants did not
need much help from the test leader, and the tasks were
performed with no or only slight support.
When using the speech interface, the majority of the tasks
were performed with no or only slight support from the test
leader, or was performed ok but with a slight mistake. Approximately
20% of the tasks needed more support or was
aborted. In the cases where the task was aborted, all in
all three times, it was due to the system not being able to
perceive the input or misinterpreting the input.
Multimodal interaction was similar to GUI interaction, although
a few tasks needed considerable support, or were ok
but with a slight mistake. In one case the task was aborted;
this was due to the user using an expression that was not
covered by the lexicon. Instead of using the keypad, the
user chose to abort and then restart the task and was able
to perform it using another expression.
5.2 Self-estimated driving ability
Table 1 shows self-estimated driving ability.
Modality SUI Multimodal GUI
Mean 7,5 7,25 5,48
STD 1,90 1,76 1,91
Median 8 7,5 6
Table 1: Estimated driving ability according to the
drivers.
The participants estimated their driving ability higher when
using the SUI or the multimodal interface, compared to the
GUI interface. A one-way Anova test shows that the difference
between the GUI compared to the SUI and the multimodal
interfaces is statistically significant, F(2,113)=12,923,
p