Usability and Interactive TV

When designing and developing web sites for interactive TV as opposed to traditional PC platforms, there are many differences to take into consideration. Broadly they can be split into two areas:

Cognitive

One of the often neglected aspects of usability design for Interactive TV is the fact that when watching TV the user is engaged in a completely different type of interaction than when using a computer. In fact, in many respects it is the opposite experience:

	TV	Computer
Type of interaction	Passive	Active
Information output	Continuous	Burst
Interaction required	Rarely	Often
Physical distance	Far	Close

This means that the user is in a very different mental state when visiting your site via the television rather than a computer. As pioneers in the field of ITV, it is up to designers and developers to make user’s leap from passive to active as painless as possible. This may involve removing more advanced functionality (less tactfully referred to as 'dumbing-down') sites that are intended for ITV audiences. It requires a fine balance to include interactivity without alienating viewers, however as people become more used to controlling their TV rather than simply watching it, this will become less of a problem.

Traditionally when watching TV, no action is required from the user - apart from the relatively infrequent changing of channels/volume etc. TV images are continuously 'streamed' to the viewer, one after the other, with no break, whereas web pages are consumed in much more of a request/wait/read cycle. Although there's not much which can be done about this in site-design terms, it is worth being aware of. In fact, due to the surge in popularity of web animation packages such as Macromedia Flash, many web sites are becoming more TV like; with an opening sequence leading you in to the site proper.

It should also be noted that non-PC-savvy digital TV users may not be familiar with the raft of PC GUI standards, even to the extent of being unfamiliar with how controls such as drop down lists work. Don't make assumptions about the experience of your users.

Physical

There are big differences between the way we view and control TV and computers. Input controls for a television are extremely simple compared to the capabilities (and complexities) of a mouse and keyboard. And, even though they may seem similar, TV tubes and computer monitors also have vastly differing output capabilities.

Input

Currently no ITV providers (in the UK) offer a mouse option. This isn’t really a surprise, because as well as requiring quite specific operating conditions (how many sofas’ do you know with a built-in mouse mat) they are also one of the major stumbling block for computer-unaware users. For example my parents, who are in their 50s, recently bought a computer and I initially helped them to get familiar with it. It was interesting to note that even when they had managed to set up the internet connection and download their email, accurate mouse control was still proving difficult.

In practical terms what this means is that users will not be 'wandering the screen' with their mouse pointers, looking for hot spots or links, as computer users may tend to. Instead they must tab between specific hot areas. Also, complicated pop-up menuing systems (often implemented in JavaScript) should be avoided, as they often rely on a mouse position to determine whether to display themselves.

Output

There is also the major issue of the difference in quality between television and computer monitor outputs. This is an often discussed topic in the field of ITV development, and normally involves care over font sizes, fine lines (interlacing) and bleeding or illegal colours. Nasty. Check out this article on Gamasutra for technical details about the issues involved.

Usability wise, the output restrictions generally mean that pages can contain less text, and there is less scope for small, subtle icons or pictures. It's become relatively common for web sites to use small point size type in order to pack as much info into the all-important first page as possible. Complete re-pagination, and possible re-editing is normally required to cope with the textual shortcomings of TV tubes.

Summary

In summary, web site developers need to think both about the physical and the mental way in which digital TV viewers will be interacting with their site. The cognitive leap between viewing and interacting can never be fully factored-out, but physical differences can be effectively negated by making the right decisions at site design time.

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