Concepting

Before people engage in face-to-face conversations, they have to determine if here and now is the right situation for discussing a certain topic. If the other party is busy with something more important, people typically postpone the conversation to a more appropriate time and place. Consider the following examples:

• Bringing up bad news to a friend ("I will wait until his important examination tomorrow is over.")
• Apologizing to wife for a fight ("It's too noisy in this bar. Need more romantic atmosphere.")
• Discussing work issues when meeting a colleague on Sunday ("He is enjoying his family life. I can talk to him on Monday at office about this")

Assessing such 'conversational appropriateness' is impossible in phone mediated communication such as voice calls or messaging, since callers simply do not have perceptual access to the situation of the callee/recipient. This is one of the reasons why phone calls and mobile messages occasionally can be experienced as interruptive, disturbing or 'out-of-context'.

The basic idea behind DeDe was to allow the sender to define the context or situation in which the message should be delivered to the recipient. In this way, the message delivery would not happen immediately (as with normal messages) but only when the recipient's phone entered the defined situation.

The benefits of such and messaging feature would include:

• From the recipient's point of view, DeDe mobile messages would delivered appropriately to the context and their content would be experienced as more 'appropriate' and 'well-timed'.
• From the sender's perspective, a DeDe message can be sent immediately when the idea of writing the message arises, getting the message-sending 'out of the way', even though the recipient is currently in a bad situation to receive the message.
• For both messaging parties, DeDe messages could potentially work as an effective social reminder system, for instance reminders about upcoming events of common interest.
• Knowing the situation in which a message would be delivered, the sender might be able to create more meaningful and expressive message content.
  

DeDe prototype and its features

During the concepting phase of DeDe, we identified a number of candidates for how a 'situation' could be easily defined by sender, constantly checked by the recipient's phone, and still be experienced as 'useful' for both sender and recipient. Since our intention was to prototype the application and run a field trial with commercially available phone models running in the normal GSM network, we had to constrain the number of context parameters to four:

• Time: deliver message to recipient at a defined time.
• Location: deliver message when recipient arrives to a location.
• Bluetooth device: deliver message when recipient comes within Bluetooth range to a defined Bluetooth device (MAC address).
• Phone call: deliver message right before the recipient calls or receives a call from a defined number.

These features were implemented on nine Nokia 7650 handset, the first S60 phone available at the time of the study. Instead of developing a totally new messaging application, we modified the existing messaging application on the phone, enabling the sender to define the delivery in the following way:

1. Create (MMS) message as normal
2. When message has been created and is ready to send, select “Define Delivery” from Options menu. (If user selected"Send" without defining parameters, user was also automatically reminded about the possibility of DeDe sending.)
4. Select and set the context type in which the message should be delivered. Time: deliver message to recipient at a defined time. Location: deliver message when recipient arrives to a location. Bluetooth device: deliver message when recipient comes within Bluetooth range to a defined Bluetooth device (MAC address). Phone call: deliver message right before the recipient calls or receives a call from a defined number. Only one parameter per message was allowed.
5. Before sending, expiration time could be set to the message. This would force the message to be delivered at that time, even though the recipient never entered the defined context. Before the DeDe message was sent, a summary of the DeDe settings were shown.

Although the DeDe message was sent immediately, and also received by the recipient's phone, the notification about the received DeDe message was withheld. (For regular messages, notifications would be triggered immediately as normal.) Instead, the recipient's phone would start a software module called DeDe observer, which would register the DeDe message and then track the recipient's context until he or she 'entered' the condition satisfying the given parameter value, for instance a location. At that point the message notification would be given.

Receiving a DeDe message notification looked the same as a normal message.

The only exception were messages defined to be delivered in connection with a phone call. In this case, the message would be displayed on the phone in conjunction with the incoming or outgoing call notification.

As is shown in step 4 above, time-based DeDe messages were defined via a simple time interface. Phone-call based DeDe messages was defined via the contact list of the phone. For location- and Bluetooth device parameter, we had to install a separate DeDe database application through which users could label, collect, browse and select locations and Bluetooth devices. Labels for locations and Bluetooth devices were created by the users, shared between users via SMS or automatically imported from a received message. These labels were then used in the message sending process (see step 4 above).

In addition a logging function was implemented to the test phones, enabling the extraction of accurate messaging activity information. This function tracked both sent and incoming messages, recording information concerning the time of arrival/sending of the message, recipient/sender of the message, as well as the use of the DeDe parameters. The log was extracted from each handset after the test period, along with the actual messages of the participants still remaining on the handsets.

User study

DeDe was validated for 33 days with a socially tight group of seven 17-18 year-olds in Helsinki. The DeDe feature was incorporated as part of the participants' existing messaging culture. Out of over 700 in-group and out-group messages, 11,4% made use of the DeDe feature. The most frequently used context parameters were location (based on network cell-ID) and time. Novel message practices emerged, as compared to 'normal' messaging, both in terms of timing of message sending, as well as creating content that specifically exploited the DeDe feature. Some use barriers were recognized, the most important being the sender's uncertainty of delivery success.

More results from the user study can be found in our CHI'05 paper.

Publications:
Jung, Y., Persson, P. & Blom, J. (2005) DeDe: Design and Evaluation of a Context-Enhanced Mobile Messaging System, Proceedings of CHI'05.

DeDe mentioned in MIT Technology Review, May 2005.