Study 4: Mobile Interaction with Advertisement Posters

This section describes the evaluation of an application of mobile interaction with advertisement posters described in detail in subsection 3.5.3 [@Perci]. This prototype supports, like the mobile museum guide application discussed in the previous section, the physical mobile interaction techniques touching, pointing and user-mediated object selection. This prototype supports a specific kind of user-mediated object selection which is called direct input. With direct input, the user does not need to look on the smart object to see the available options because they are presented on the mobile device, e.g. via a drop down menu. The same options are also shown on the smart object and can be used to support the interaction on the mobile phone. Examples are the four movie posters (see following Figure 35) that show the available movies. When looking at the poster this can help the user in the decision for one specific movie, e.g. because she likes the design of a specific poster.

The interactive poster that supports the purchasing process (see following Figure 35) provides action tags and parameters tags. After an action tag was selected, several parameter tags have to be used. The action tags offer the functionality for getting information about an advertised movie and for buying tickets. Through the parameter tags, a specific movie, a cinema in which the user wants to go, the number of persons for whom a ticket should be bought and a preferred timeslot can be selected.

Touching Pointing User-mediated object selection

Figure 35: Usage of the three interactions techniques taken during the study [Broll 2006, Siorpaes 2006].

Every option is accessible through an augmentation by an NFC Mifare tag (touching) as well as through a visual marker (pointing). The layout of the poster does not define an explicit sequence for the interaction with the poster reflecting the implementation which also does not prescribe a predefined sequence. Thus all physical parameter tags can be clicked in an arbitrary order after the corresponding action tag for buying a cinema ticket

4 Evaluation and Comparison of Physical Mobile Interactions

has been selected. This allows the user to proceed in the way she thinks is most appropriate.

In June 2006 a user study was conducted to evaluate this prototype and to compare the three supported interaction techniques touching, pointing, and user-mediated object selection. The goal of the study was, besides the evaluation of the interaction techniques, the evaluation of the concept of such a mobile ticketing application and its current implementation. The following text just concentrates on the evaluation of the three supported interaction techniques. 17 participants took part in the user study, aged from 23 to 46 years. The average age was 29 years. 4 testers were female and the other 13 male. After the preliminary interview, the participants had to fulfil a predefined task with each of the supported physical mobile interaction techniques. The task was to buy a cinema ticket using predefined settings for movie, cinema, number of persons and timeslot. The sequence of the usage of the interaction techniques was alternated from user to user to avoid undesired side effects.

Many participants could, in the beginning, not imagine possible workflows for the interaction with the poster. A common statement was How do I start? Many people are used to explicit workflows such as starting at the top and continuing to the bottom when filling out a form. Another example for a known workflow is opening the SMS application on the phone, writing the text, selecting the recipients and sending the message. The participants in this user study were confused by the fact that there was no predefined sequence to select movie, cinema, time slot and number of tickets. This problem was partly already identified in a preliminary study based on a paper prototype that is described in [Broll et al. 2006b]. Because of this, the poster as well as the mobile phone application provided different hints of how to use the prototype. But as previous work has already shown and as it was proved again in this user study, people often ignore and do not appreciate such explanations.

As already mentioned, the poster had been augmented with action and parameter tags. The user had first to select the action she wants to perform (e.g. order a movie ticket) and then had to select the corresponding parameter tags like movie title or time slot. Many people did not understand this distinction without a corresponding explanation or reading the instructions carefully.

After the usage of the prototype we asked the testers how easy it is to handle each of the interaction techniques and how funny, innovative and reliable they are. The possible answers were: completely applies (4), somewhat applies (3), do not know (2), somewhat not applies (1) and not applies at all (0). The average of the given answers is depicted by the following Figure 36.

Touching followed by user-mediated object selection were seen as easy to handle. The result for user-mediated object selection is negatively influenced by the fact that two participants had serious problems with using the HTML browser on the mobile phone used for the implementation of this interaction technique. Pointing was not seen as easy to handle because the testers had problems to take a picture of the entire visual code in a sufficient resolution. This result probably improves when using a real time recognition implementation of the visual code system.

4 Evaluation and Comparison of Physical Mobile Interactions

Many testers said that touching is a funny interaction technique. They primarily answered

do not know or somewhat not applies when thinking about pointing and fun. User-mediated

object selection was not seen to be funny at all.

Most testers saw touching as an innovative interaction technique, were often undecided when thinking about pointing and saw user-mediated object selection not as an innovative interaction technique.

Touching and user-mediated object selection were seen as reliable interaction techniques whereby they were undecided when thinking about pointing.

3.4 2.7 3 3.5 0.9 1.7 2.5 1.7 2.9 0.9 _0.8 3.7 0 0.5 1 1.5 2 2.5 3 3.5 4

Easy Handling Funny Innovative Reliable

Touching Pointing User-Mediated Object Selection

Figure 36: Rating of touching, pointing and user-mediated object selection.

Most testers said that user-mediated object selection is not a funny or innovative interaction technique. This is probably because people already knew and have already used this interaction technique.

The results for pointing were in general negatively affected by its implementation that needs a few seconds till the user knows whether she has successfully captured the visual code or not.

Before and after the user study the participants were asked which interaction technique they preferred and which of the three was the fastest. Before the study, 13 testers preferred the interaction technique touching whereby one preferred user-mediated object selection and one participant was undecided. 2 participants did not answer this question. After the user test, 13 participants preferred touching and 4 user-mediated object selection.

Before the study, 14 testers said that touching and 1 participant said that pointing is the fastest interaction technique. 2 participants did not answer this question. After the user study, 12 persons mentioned that touching was the fastest technique whereas 5 mentioned user-mediated object selection.

When looking at the overall result, touching is seen as the best interaction technique when taking the four analyzed attributes and the questions regarding the preferred and fastest interaction technique into account. Touching was highly ranked in all questions regarding the four attributes easy handling, funny, innovative and reliable. User-mediated object selection is seen as a reliable interaction technique that is easy to handle but is not innovative or funny. Pointing received the worst marks but is seen as more innovative and funny than user-mediated object selection.

4 Evaluation and Comparison of Physical Mobile Interactions