Introduction
A Personal Digital Assistant (PDA) such as the Palm or Handspring, is in every sense a useful device. As new users would discover though, a PDA’s intuitive user interface quickly becomes non-intuitive when trying to enter alphabets through its graffiti pad. To be able to use the graffiti pad, the user needs to learn another language, that of the PDA. This is the case with most portable digital appliances today. The demand for appliances that help us to remain mobile, in an increasingly mobile world has brought many portable digital devices to the market. These devices range from music players to cell-phones to e-book readers. While the overall ergonomics of products has improved over the years, functional interactivity between the user and portable devices has not seen much improvement. These devices do not react to users inputs in a natural manner. Should users change their natural ways of working to handle a new portable device? This article discusses the issue of natural interfaces, and finds out how technology is trying to make these devices more easy to use, and “vanish” within our daily lives.
About portable devices
Portable devices come in a number of flavors. These can be broadly categorized into,
a. Devices that help us to access digital content on the move (like music players, VCD players, Image viewers, e-book readers, e-mail readers)
b. Devices that help us to be accessible while on the move (like cell-phones)
c. Devices that assist in organizing (like PDAs)
d. Devices that combine the above functions into one (like a cell-phone / PDA combination)
Unlike desktop computers, handheld devices are designed for specific tasks like acting as an organizer, or as multimedia players. Some appliances add the functionality of sending and receiving mail, or reading an e-book, or viewing an image. These devices have requirements that are different from other types of computers. They have to be accessible at all times. They have to be small in size. Some of them double up as devices for displaying large amounts of information. Low-end devices do not have colour displays because of cost constraints. And finally, they have fairly limited processing power and storage memory.
Convenience, and interfaces
Many portable devices are designed to provide convenience. For instance, portable multi-format audio (MP3/WMA/other) players offer the convenience of carrying our music anywhere. This music is stored in a storage device like CD/Hard disk/removable cards. A 650 MB CD player can store about 150 average sized MP3 songs. A 5 GB hard-disk based player can store about 1000 songs. Thus, these devices provide tremendous convenience in making music mobile. But the problem of identifying the best method of showing the information about a thousand songs, in a small display has not been satisfactorily solved yet. Another issue arises, when a device provides an alternative to an already existing physical action. For instance, we flex our fingers to turn the pages of a physical book. On the other hand, in e-book readers, the user “clicks” on a button to turn a page. Humans mainly communicate through voice, whereas most cell-phones respond only to button presses. And while we perceive and associate various moods with colours, portable digital devices have remained astutely remote from the moods of the user, with the same response every time.
Three major issues in interfacing with portable devices are discussed in the following paragraphs.
Issues in receiving user input
Most of the portable devices get their input based on clicks or presses (Cell-phones / PDAs). Some of the devices (like eDigital’s MXP 100 audio player) can be activated by limited vocabulary speech. Some devices like the Palm have limited character recognition capability. For actions that have a strong physical equivalent (like turning a page or rotating a knob), it is difficult to accomplish with a click. It takes time for new users to associate an action with an icon or formatted text.
Issues in user identification
Humans identify each other reliably through various senses, but mainly through sight and sound. Portable devices still depend on passwords for user authentication, which is more suited for the world of desktop computers. But user authentication through “natural” means, by using fingerprints is coming to the fore. Laptops from companies like Acer already incorporate this, and other companies are following suit.
Issues in displaying information
Most portable devices do not have colour displays, and hence lack the capability to differentiate responses by colours. The display size is also limited. For portable devices that integrate a lot of functionality, it is hard to design an optimal user interface, which can communicate to the user in an intuitive manner. A recent portable MP3 player in the market has around 10 buttons, and the following functionalities. Sorting by artist, album, title, more than 10 special effects / volume control, exploring content of directories, song selection, song recording, song name input in alphabetical manner, fast forward/ rewind, and interface to PC. This example shows how a lot of functionality has been squeezed into a limited number of buttons. The size of the displays in portable devices is also less, compared to the amount of information that needs to be conveyed/received. Though desktop computers interact with large amounts of information, the options for interacting with the user are also correspondingly more (large colour monitors, speakers).
How has technology responded to these challenges?
The coming wave – future products
Several innovations have been proposed to tackle this problem of “high ratio of information content in a limited display size”, met in portable devices.
Researchers have noted that colour/light changes can be effectively used to passively convey information, without requiring user intervention. This concept, called “calm computing”, has been applied effectively in conveying stock market, and weather information in devices like cell-phones. Instead of disturbing the user’s environment by disruptive means like ringing, these devices employ non-disruptive means like change in colour of the screen, to display information changes. For instance, a sudden increase in stock activity is indicated by a change in colour to red.
“Intelligent interfaces”, are seen in devices that respond to movement, or sound, or touch. Such interfaces can discern changes in the environment and change accordingly.
In devices that have the need to scroll through lots of information, physical movement can be used to scroll, instead of button clicks. In PDA’s that have this feature, users can tilt the PDA to scroll through information. The direction in which the PDA is tilted determines the direction of scroll. Micro-sensors placed inside the device identify the tilt, and make the device respond to the tilt.
To make the task of using a new appliance easier, the interface can be made as close as possible to actions in the physical world. This paradigm, referred to as “Embodied User Interface” by Xerox, is being applied in portable appliances. These products allow the user to tilt the appliance to scroll through menus, move through pages of e-books using a flip of the hand, use various levels of pressures to transmit information to the device, or provide good gaming experience without using the keyboard or mouse. By allowing users to operate the device as if it were the “real” physical object itself, this technique allows much better personalization of the device.
Summary
To improve user interfaces in portable digital devices, and make them intuitive, a number of schemes have been proposed that respond to sound/voice/touch/movement. To realize these new applications, various kinds of sensors would be needed in portable devices, like pressure/acceleration, and light/sound sensors. As the cost of these sensors decrease, we can expect more and more products to employ these techniques, and make personal digital devices to interact in more natural ways, and hence “vanish” into our lives.
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