Discussion of Both Experiment 1 and 2

The quantitative and qualitative results of Experiment 1 and 2 validated these distinct advantages of CROSSFLOW:

A. Facilitate navigation in certain type of indoor environment and support multi- tasking while navigating.

Wright et al. (1993) stated that finding a particular destination could be difficult in many modern building complexes, where there were many visually similar spatial structures such as corridors, doorways and visually similar information or objects. Among those buildings, some of them contain relatively less and sparser decision points and there are many possible target objects, directions or destinations at each decision point. Some of the indoor environments contain relatively more and denser decision points (i.e. the distances between decision points are small) and there are less than four possible target objects, directions or destinations at each decision point.

The results of Experiment 1 and 2 imply that when a user uses an aid to navigate or search physical objects, in comparison with hand-held paper map, CROSSFLOW probably is more efficient and impose much lower workload on users in the former type of indoor environment, while not so efficient and impose a similar level of workload on users in the latter type of indoor environment. Moreover, CROSSFLOW supports multi-tasking while navigation and is as effective and successful as hand-held paper map in both types of indoor environment.

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B. Support personalized navigational information presentation for multiple simultaneous users without resorting to location tracking.

In contrast to the GAUDI system (Kray et al. 2005) reviewed in Section 4.2.2, the results of Experiment 2 show that CROSSFLOW scales well with multiple simultaneous users. All users successfully completed their navigation tasks. Moreover, an increased number of users would not likely result in any deterioration of system performance.

Technically, when using CROSSFLOW to navigate, there is no need for tracking individual users or for network connectivity beyond the initial registration, which is particularly difficult for indoor environments. Beyond selecting the target location and synchronizing the time, no further interaction is needed between the server of CROSSFLOW and user's mobile device. Although in Experiment 1 and 2, target locations were predefined and devices were synchronized before being given to the participants, it is straightforward to realize these steps using only unidirectional transmissions (e.g. from the server to the mobile device). Not only does this reduce the cost of sensors and the requirements imposed on the mobile device (e.g. it only needs to be able to receive information but not to send it after initial registration), but also contribute to the increased degree of privacy and anonymity when people navigating.

C. Preserve certain level of privacy and anonymity in physical public spaces.

As reviewed in Chapter 2, a person's privacy and anonymity in public space would be impaired when the relationship between the person and the information he/she owned or interacted with and the information content were exposed to occupants in the same space. For example, when a person constantly interacts with his private information on his mobile phone screen in a shopping mall or a railway station, his privacy and anonymity in that space will be impaired as his acts of interaction and information content on his mobile phone are exposed to others by shoulder surveillance.

CROSSFLOW only need a user to interact with his mobile device once to download the schedule of the time slots (i.e. the cue mapping) for an environment. No further interaction is needed during the navigation process unless the user needs to select a new destination. During navigation, the relationship between the user and the information he owned (a specific pattern relevant to the user in this case) is hardly identified by other occupants in the space. Furthermore, the content of the information relevant to a user (the

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directional information in this case) is represented by abstract ambient patterns and can only be decoded in conjunction with the user's private cues (i.e. the vibrations from the user's mobile phone) that can hardly be detected by other occupants of the space. Therefore, a certain level of privacy and anonymity of the user could be preserved without hindering the user‘s interaction with, and access to, public space, though there is a possibility to undermine user‘s privacy and anonymity by hacking the server and the user‘s personal mobile device or constantly observing and following the user.

The feedbacks of the participants of Experiment 2 (i.e. Section 5.3.3 B. (2) (c) in the comments of the participants which are evidently positive about the CROSSFLOW system) have proven that preserving user's privacy and anonymity in public space is a distinct advantage of CROSSFLOW over traditional map-based and tracking-relied navigation aids or approaches.

D. Aesthetically pleasing and fun to play with.

This advantage has been demonstrated in the qualitative results of both Experiment 1 and 2.

5.5 Conclusions

This chapter has reported the evaluation of CROSSFLOW V1, the first version of Crossmodal Display for indoor navigation. The evaluation contains two user studies which investigated the usability and the user experience of CROSSFLOW as an indoor navigation aid in comparison with traditional hand-held paper map.

In the first user study (Experiment 1), individual participant was given dual tasks to perform using either CROSSFLOW V1 prototype or hand-held paper map. In the second user study (Experiment 2), multiple simultaneous users navigated within a maze-like complex indoor environment using either CROSSFLOW V1 prototype or hand-held paper map. The quantitative and qualitative results of two experiments have proved the success of the design of CROSSFLOW and our conceptual model of Crossmodal Display, and validated the effectiveness of CROSSFLOW as a solution to help to solve the problems identified in Chapter 2 in indoor navigation application domain, in particular, validated

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these distinct advantages over traditional navigation tools and existing technologies we reviewed:

 Facilitate indoor navigation and support multi-tasking while navigating.

 Support personalized navigational information presentation for multiple simultaneous users without resorting to location tracking.

 Preserve certain level of privacy and anonymity in physical public space.

 Not use or only use limited sensing or tracking.

 Aesthetically pleasing and fun to play with.

The results of also showed that the quantity and density of decision points in the indoor environment have greater impact on the navigation efficiency and workload on users when using CROSSFLOW than using traditional hand-held paper map. Moreover, the usability and the user experience of CROSSFLOW were impaired not only because of environmental factors such as the quantity and density of decision points and the shadows of the obstacles and the occupants of the environment, but also the components designed for CROSSFLOW V1 including the fish-flow pattern and short beeps and vibrations.

In order to improve the usability and the user experience of CROSSFLOW, we developed a new version of CROSSFLOW (CROSSFLOW Version 2) based on further analysis of findings of Experiment 1 and 2 and implications from them, the process of which is reported in Chapter 6. The evaluation of CROSSFLOW V2 is reported in Chapter 7.

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