Someone asked me recently how many items were ‘too many’ to have in a navigation bar on a website. Of course, there is no definitive answer to this (and please don’t ever believe it if someone tells you 7+/-2: the research behind that is completely irrelevant). I don’t think I’ve seen reliable research on this, and if I did I think I’d be suspicious of it anyway as the complexity of the issue isn’t about number, but about complexity of concept.
So I spent some time thinking about what the underlying principles would be if you had to think this through for a decision (I always like thinking from basic principles out, not just relying on simple answers).
One of the main principles is Hicks Law. This describes the time it takes for a reader to make a decision when provided with a number of choices. It basically says that the more choices, the more time (obviously) but it is a logarithmic relationship, not a linear one. So that’s one part of it.
Another important part is the concept of basic-level categories. There is a level of a hierarchical classification that is called ‘basic’ that is more cognitively real than other levels. People think at the basic level. A simple example is this: Mammal – dog – dalmatian. We usually think about ‘dogs’, not mammals or dalmatians.
In practice, I’ve seen people cope with long lists when:
- the items are at the reader’s basic level
- the content in the list feels like it belongs together
- the sequence of items makes sense to the reader (this may mean they are clustered sensibly, or alphabetic for known-item tasks)
- the concepts are known to the reader
The opposite to a long list of course is a shorter one. This will usually mean breaking down the long list hierarchically, or group some of the items together (e.g Products & Services). The challenge with this is doing it in a way that still makes sense to the reader – as the level of abstraction increases, it is harder for people to determine what might be in a more abstract category.
The other challenge is that, even if you do make a really good long list that is full of great terms and works well for readers, everyone else will challenge you because there is a perception that long lists are bad (even users will say ‘oh, that’s a long list’ before they jump in and use it really easily). If I were about to do implement a long list I’d set up a mini-usability test that compares a couple of options – long lists, grouped items, more hierarchy). I developed a quick usability testing method years ago that I still use that would be good for showing whether the list works or not.
What do you think? How do you figure out how long to make your navigation lists? And how do you convince other people that a long list is OK?