4 Evaluation and Comparison of Physical Mobile Interactions
4.4 Study 3: Mobile Museum Guide MOPS++
This section describes the evaluation of the mobile museum guide MOPS++ (Mobile Point of Interest System) [@PEMS 2006] whose functionality and implementation was already discussed in subsection 3.5.2. This prototype supports the interaction techniques touching, pointing and user-mediated object selection to choose an exhibit in a museum. User- mediated object selection is the most typical interaction technique used in such guide and is therefore also supported by this prototype. In addition to this touching and pointing are integrated as novel interaction techniques that require a shorter distance to the exhibit. The implementation of touching is based on an external RFID reader attached to the mobile phone and the implementation of pointing is based on the visual code system.
MOPS++ was tested in May 2006 by 8 persons within a university building in which part of a train museum was simulated. There were no real exhibits, but posters showing a picture and a description of it in English and German were set up instead. Each poster was augmented with an RFID-tag (1 Kbyte, ISO 15693-3), a visual marker and a number to support all three interaction techniques. This section describes a user study for testing and comparing these three supported interaction techniques.
The following Figure 31 shows the usage of these interaction techniques during the user study. Figure 31a shows how the mobile device is used to read an RFID tag (touching), Figure 31b shows the reading of a visual marker (pointing) and Figure 31c shows the direct number input.
4 Evaluation and Comparison of Physical Mobile Interactions
a b c
Figure 31: Usage of the three interactions techniques taken during the study.
The user study was split into three phases. In the first phase we collected demographical information about the participants (age, profession, sex, etc.) and asked questions regarding the usage of their mobile phone and their prior experiences with mobile guides as well as their opinion about the three supported interaction techniques. In the second phase every participant used each interaction technique twice whereby the sequence of the used interaction techniques was uniformly distributed. 7 participants were male, 1 female. The participants were between 23 and 45 years old with an average age of 28 years. We explained the idea behind MOPS++ and again asked questions regarding the supported interaction techniques. The following Figure 32 shows the results of the question What is
the best and what is the fastest interaction technique?.
0 1 2 3 4 5 6 7 8
Touching Pointing User-mediated object selection
p a rt ic ip a n ts before aftwards 0 1 2 3 4 5 6 7 8
Touching Pointing User-mediated object selection
p a rt ic ip a n ts before aftwards
Figure 32: Best (left) and fastest (right) interaction techniques before and after the study.
The results show that before and after using the prototype, most participants preferred touching and some of them user-mediated object selection. Nearly nobody mentioned that she or he thought that pointing would be the best or fastest interaction technique. The reason for that is that a person in a museum is already close to an object to perform touching. The most noticeable disadvantage of touching, that the user must be nearby the object, has no impact in this context.
Furthermore, we asked the participants after having used the prototype to rate the interaction techniques regarding the attributes funny, innovative, reliable and simple. At this they could choose between the following possible answers according a Likert scale:
4 Evaluation and Comparison of Physical Mobile Interactions
completely agree (4), partly agree (3), do not know (2), partly disagree (1) and disagree (0). The corresponding results are depicted in the following Figure 33.
2.4 3.1 3 3.6 2.6 3.5 2.9 2.4 0.7 0.4 3.7 3.9 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Funny Innovative Reliable Simple
Touching Pointing User-mediated object selection
Figure 33: Average rating regarding the adjectives funny, innovative, reliable and simple.
In addition to that, we asked the users what they would rate to be the funniest, innovative and reliable interaction technique. Furthermore, we asked them which interaction technique they would continuously use. The corresponding results are depicted in the following Figure 34. 0 1 2 3 4 5 6 7 8
Most funny Most innovative Most reliable Continuously using
pa rt ic ip a n ts
Touching Pointing User-mediated object selection
Figure 34: Rating regarding fun factor, innovativeness reliability and usage.
As one can see when looking at the previous two figures, touching and pointing are seen as funny and innovative interaction techniques. In contrast to that, user-mediated object selection and touching are seen as reliable interaction techniques whereby this is not the case when looking at the results of pointing. The reason for this is again, as it was in the previous study, the complexity of taking a picture of the complete marker in a sufficient resolution. This is also one of the reasons why pointing is not seen as a simple interaction technique whereas touching and user-mediated object selection got good results regarding this question. Furthermore, most participants would prefer the interaction technique touching when continuously using such a system.
4 Evaluation and Comparison of Physical Mobile Interactions
Even if the context of a museum was just simulated and due to the fact that just 8 participants took part, this study shows the preference of people for touching, their interest in pointing and their trust in user-mediated object selection.