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Insights for the TV Interface from the Mobile Phone Interface

Younghwan Pan and Young Sam Ryu

Journal of Usability Studies, Volume 4, Issue 4, May 2009, pp. 166-177

Article Contents

User Interface Model

IBM (1992) and Mandel (1997) suggested there are three models to configure the user interface: the userís mental model, the programmerís model, and the designerís model. It is important to understand each of the three different perspectives for user interface design. Thus, if we revise IBMís user interface model to apply to TV and mobile phone usage, the three entities would be user, designer, and developer (Figure 2). This model will allow us to view both TV and mobile interfaces in three different perspectives in order to incorporate the design differences for positive impact.

Figure 2

Figure 2. User interface model revised from IBM (1992)

Userís Model

TV users are in a passive mode while watching TV. Thus, TV user interface design should reflect the changes in the passive mode of the user. The traditional TV task is for users to watch programs displayed on a TV screen. In this context, the userís only active task is to change channels or control volume. Digital TV provides additional interactive services so that users need to be in active mode to fully utilize them. However, it is not easy for users to adapt their attitude toward the active use of TV. The success of traditional TV is based on the fact that viewers do not need to do anything other than relax and watch. Also, viewers are not motivated to search and select program contents if these services are not offered at a reasonable price (Wyss & Vong, 2001). Thus, service providersí effort to reduce the cost of using interactive digital TV service will be necessary to encourage the active participation of viewers. With the advancements in technology, more functions are implemented in electronic products that require active user participation. Thus, the user acceptance level of newly introduced functions should be studied carefully.

For mobile user interface design, there are two different perspectives in device design. These perspectives are due to the convergence of various functions into the device. The first perspective is to consider voice conversation as the main function of the device, and the other added functions such as MP3, camera, or mobile TV are the sub- or supplementary functions. The other perspective is to look at all the functions at the same level of importance, which means any function including voice conversation, MP3, camera, or mobile TV can be the main function of the device at any time. For example, the phone function of the iPhone seems to be an extra function built into an iPod Touch, which is mainly an MP3 player, because both iPhone and iPod Touch have the same basic look and interface structure, and because the iPhone evolved from the iPod.

We should also observe that users only recognize an integrated experience. So, users are not really interested in recognizing who (manufacturer or service provider) provides which function or service of TVs or mobile phones. Thus, it raises the important issue of cooperative design of user interface among different organizational entities (such as device manufacturer, service provider, and content provider) to optimize the integrated user experience that is presented through the user interface.

Designerís Model

To effectively design interfaces, designers must understand both users and manufacturers. Designers are tasked with making compromises between the two incompatible goals of being easy to use and easy to make. TV and mobile phones are more limited than PC products in terms of design. While a PC can solve various usability problems with the help of software, TV and mobile phones must allocate most resources to their main tasks.

Identity is one of the most important elements in design. Device manufacturers want to maintain their identity regardless of a service provider. In other words, mobile phone manufacturers want to supply their phones to as many service providers as possible. Conversely, service providers want to maintain their identity regardless of device manufacturers. After all, the same effort by the two different parties can produce negative user experience. To improve the integrated user experience, the needs of cooperative design between manufacturer and service provider become essential.

Developerís Model

This model is based on the perspective of development and technology. Developers focus on the appointed date of delivery and quality of their products. From this point of view, the difference between the device manufacturers and service providers is more significant than the difference between TV and mobile phones. Device manufacturers are more resistant to changes because they have the process of manufacturing and evaluation, while service providers are more willing to change to accommodate user desire for enhanced services. Manufacturers perform more evaluation and undergo a verification process when they introduce a new design of user interface or technology. Iterative design is a critical process for successful interface design; however, the cost of an iterative design process in a manufacturing firm is significant.

Comparison of Interaction

Interaction design is a more extensive concept than user interface design. However, the interaction design referred to in this paper will only be limited to the actual and specific interactive behavior between products and users. Foley et al. (1990) introduced six types of interaction tasks including Select, Position, Orient, Path, Quantify, and Text. With the Select task, the user makes a selection from a set of alternatives such as a menu. With the Position task, the user indicates a position on the interactive display using input devices or type-in coordinates. The Orient task requires the user to control orientation angles of an entity. The Path task is a series of positions or orientations over time. The Quantify task asks the user to specify a value, and the Text task prompts the user to input a text string.

Input interaction indicates input navigation, while input device means a physical device to provide data or control signals. Input interaction includes pointing interaction, jumping interaction, and recognition interaction based on the electronic products available in the market. Pointing interaction is based on the moving cursor imposed over the applications on screen independently. Typical input devices used for pointing interactions are a mouse, a touch pad, or a track ball. The jumping interaction uses a cursor or a highlighted box subject to the applications on screen and they only move around the designated areas. This interaction typically performs the selection task. The recognition interaction performs Select, Quantify, and Text tasks through voice recognition, handwriting recognition, or gesture recognition.

The main interactions used in TVs are the Select and Quantify tasks, whereas the main interactions used in mobile phones are the Select, Text, and Quantify tasks. The jumping interaction is used as input interaction for both TV and mobile phones. The pointing interaction was adopted for early Internet TVs in the 1990s; however, it has been replaced with the jumping interaction. Also, the jumping interaction is the most popular method used in mobile interfaces. Recently, manufacturers released mobile phones with a touch screen using the pointing interaction; however, service providers provide applications and services based on the jumping interaction to support non-touch screen phone users. The interaction task, input interaction, and input device for both TV and mobile phones are summarized in Table 4.

Table 4. Interaction Characteristic for TV and Mobile Phones
Interaction TV Mobile phone

Interaction task



Input interaction

Jumping interaction

Jumping interaction
Pointing interaction (touch-screen phone)

Input device

Numeric keypads
Directional keys + OK button
Color soft keys

Numeric keypad
QWERTY keyboard
Directional keys + OK button
Left and right soft keys
Click-wheel on the side
Finger trackball
Isometric joystick
Touch screen
Voice recognition

TV and mobile phones share a very similar approach in input interaction and input device. This typical approach is different from the interaction provided by recently popular touch screen phones such as the iPhone and LG Prada. Navigation has not been a popular task for TV usage. However, as a result of the addition of various functions and services such as EPG, DVR, and PPV, directional keys with an OK button have become a basic component of TV remotes. These features are in addition to the channel and volume control buttons on remote controls as well as the color soft keys with four different colors (red, green, yellow, and blue). Basically, each color key represents the function indicated on the bottom of the TV screen as a soft key similar to left and right soft keys on mobile phones (Figure 3).

Figure 3

Figure 3. Examples of directional keys and soft keys

Although mobile phones have utilized various ways to support navigation tasks, the four-way directional keys with an OK or a Select button have become the popular method with the left and right soft key for non-touch screen phones. Recently, Blackberry introduced a finger trackball for their new models instead of directional keys and a click-wheel on the side of the device. The click-wheel, which is usually implemented on the right side of the device, can be very intuitive and quick for the jumping interaction, but it may not be a good solution for left-handed users. In contrast, a trackball can be used by either hand. Also, there was an attempt to adopt an isometric joystick (Chau, Wobbrock, Myers, & Rothrock, 2006), which has been used for Thinkpad laptops instead of a touchpad. The input devices already present in the market make it difficult for the emergence of new input paradigms. For example, the Prada phone by LG, which mainly uses a touch screen as the input device, also adopted directional keys with an OK button on the screen in case users still want to use this approach instead of the touch screen pointing interaction. Thus, new input devices face challenges because users are accustomed to the previous input devices.

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