Nevertheless, I'm going to use the TiVo user interface as an example of how not to write user interfaces. It seems that they cobbled together something pretty basic when they got started in 1999 and they haven't improved it since. There have been a few minor tweaks and/or name changes but nothing substantial. I don't have the Roamio -- maybe the user interface there is different [see postscript] -- but the classic UI on my "series 3" is simply a bad design that has never been fixed.
According to Wikipedia, there are seven principles of user interface design. While the TiVo design does an adequate job with six of the seven principles, I believe it falls quite short in the seventh:
- Conformity with user expectations: the dialogue conforms with user expectations when it is consistent and corresponds to the user characteristics, such as task knowledge, education, experience, and to commonly accepted conventions.
Let me start with the simplest and most fundamental error: when you are, say, watching live TV and you go up to the top-level menu, you would naturally expect that "live TV" would be the current selection. But no, "Now Playing List" is the new selection. That means that if you inadvertently clicked up to the menu and then pressed "Select" you would expect to be back watching live TV -- but you aren't. That breaks perhaps the #1 rule of user interface design: the principle of least surprise. Or, to put it in terms of the above definition, the UI is supposed to be conform to user expectations and be consistent.
Another major mismatch between the TiVo UI model and the way viewers think: channels. Back in the day when there were just a few channels available, essentially one per network, the concept of a channel meant something. You just "knew" which channel a program would be on and it didn't make any sense for it to be on a different channel. But that situation was long gone, here in the USA at least, when TiVo was introduced so it has never made any sense. The viewer simply doesn't care which channel something is on. And, truth be told, neither does TiVo. Yet the user is required, when setting up a Season Pass, for example, to specify the channel. The Season Pass largely ignores this information because it actually lists all of the upcoming episodes, regardless of channel. The user does distinguish between first-run and repeats. And TiVo asks about that. But when listing episodes, it doesn't make any distinction. Consistency!
Another issue that is a fundamental breach of UI design (but strangely is not mentioned in the Wiki article) is that the controller should always be "live." That is to say, there should never be an operation that the user can initiate that he can't cancel or switch to some other operation. Frequently, TiVo goes into a funk while it is reacting to a user command -- and the user is helpless until the action finishes. And there isn't even an indication of how long the action is likely to take.
But my biggest complaint of all is that TiVo has not changed the model to accommodate high-definition TV. Although HDTV was, in theory at least, around in 1999 when TiVo was launched, it didn't become mainstream until the mid-2000s. The PBS HD channel began operations in 2004, for example. Should TiVo have anticipated HD? Of course they should, but it probably would have been acceptable for them to remodel the UI after their first few years of operation. Note that I am talking about the UI here. At some point (around 2005?) new TiVos did support recording and playing HD programs. But the UI continues in blissful ignorance of this rather important concept. For example, when setting up a Season Pass, you cannot specify that you do (or do not) want to record in HD. You can try to persuade the TiVo by specifying you want to record from an HD-only channel (in order to do this, however, you have to delete the old season pass and reprogram it -- unbelievable). But even then, the only way you can insist that a program be recorded in HD is to tell TiVo that you don't receive the corresponding non-HD channel(s). Bizarre in the extreme.
There are many other issues that I have with the TiVo UI. Things that they certainly ought to have fixed in 13 years! But I've covered the main points.
The conclusion? When you're designing a UI, don't think about the way your system works, or how the information is stored in your internal storage. Think about the way the user will want to interact with the system, how he or she will "think" about what they are doing. Model that instead and make all of the interactions consistent with that model. Yes, that's work. But isn't that what your paid for?
OK, back to work!
Postscript: I drafted this on 10/31 and the very next day my TiVo expired (the fan stopped working). No, I don't think it was a conspiracy between Google and TiVo. The TiVo people were quite helpful in getting me an upgrade to the Roamio. It was a significant operation to get it working, requiring collaboration with three different and not entirely cooperative entities: TiVo, Comcast and me. And my old expander disc, while "compatible" with the new model, is completely unreadable. So, basically, I lost everything that I had previously recorded. This seems the height of poor system design. Why on earth would they consider the internal disc and the external disc to be one single volume?
But the look and feel has improved enormously. The TiVo menus are now in HD and they have fixed quite a few of the problems I mentioned above. How is it, though, that those improvements were not available to the old Series 3? There are still breaches of the principle of least surprise. For instance, if you set up a season pass now and choose "new" only, the default channel chosen will, it seems, most likely be a channel that only shows re-runs. You can change it if you happen to notice, but TiVo will not warn you that the season pass will do nothing.