Tag Archives: miller

Hierarchies: Categories vs. Vectors

I just updated an older (2001) article of mine on SAP Design Guild, dealing with a topic I care about: the ubiquitous hierarchies used to structure information, and why they tend to fail in lots of cases. Computers have made them so seemingly indispensable (think Windows Explorer, think Mac OS Finder, think about every application you can think of), and yet in most cases that's just because today's development tools make it so much easier for developers to create hierarchies than to implement some different, more innovative, maybe more adequate approach. From the introduction:

Human beings are limited in many ways. Beside others, one limitation lies within the amount of information they can process or hold in working memory for a time given. That’s where Miller’s famous "seven plus/minus two" rule comes from – you can only have up to nine chunks of unrelated information readily accessible in short term memory. (You’ve probably already heard people telling you, "Don’t put more than seven items on a PowerPoint slide", or "Don’t build your menu structures more than seven items wide". While it’s certainly a valid recommendation to restrict yourself and not to overload your slides, Miller’s rule has been misunderstood quite often: Miller states people have great difficulty keeping more than seven or nine unrelated elements in mind. If they try to concentrate on more, access performance decreases rapidly. This doesn’t mean you cannot work with more than nine elements – if you find a way to organize those elements or to find a relation between them, it’s easy to keep lots of items readily accessible. See Don Norman’s excellent books on this subject.)