Author: Victor

I had a great session at work recently massaging a general taxonomy to be navigable. Hunched over wireframes and a hierarchical view of the taxonomy with a programmer, business analyst, and manager we were all able to communicate and understand the issues.

This is an important area of IA that is getting to be more like science and less like art. Personally, I still think bottom-up design sucks when used for navigation. The idea that you can, say, create a taxonomy without knowing who will use it or how is just ridiculous, and the more different users and users you apply to it the more its usefulness is diluted; the effect is proportional.

For example, a hierarchical taxonomy may not be balanced (an equal number of children for each parent), it may be deeper in some places than others. This may make it difficult to pull the data out and put it into a standard template (which is the advantage of having the info organized that way ahead of time), ending up with some pages that have too little content and others which have too much. With the philosophy that the UI is designed for the users’ needs, it’s the taxonomy that is the problem here.

Depending on the labels, leaf nodes may not be findable from the top of the tree (can someone look at the top-level category and ‘smell’ what’s a few levels down?). If we have this problem, we might start collapsing some levels. Then we look to see if this results in pages that are too long and balance the levels and the size of the pages: the taxonomy dance. But our information isn’t static, and we can’t always predict how the taxonomy and the information inside it will change.

That said, sometimes you have an underlying structure like a hierarchical taxonomy and need to stick a user interface on it. When this happens it’s best to have a layer of abstraction between the two so that the UI can serve the needs of the user. The layer of abstraction might just be very clever database queries. But this assumes the database is modeled to allow a flexible UI, for example, not hard coding hierarchical associations. I still haven’t arrived at the point of a method we can follow when doing this, it’ll take collaboration with a database programmer to do so.

Later…I had asked “can someone look at the top-level category and ‘smell’ what’s a few levels down?” That’s important for directed search, where you may be looking for grandchildren. It’s not as important for exploratory browsing: If you can smell the children categories under each parent, you can gradually work down the generations.

Notes on Transitional Volatility (PDF) by David Danielson (2003), also the topic of his master’s thesis. It’s a rare, rigorous look at the common guideline to ‘make navigation consistent’ in a world that has big websites where the navigation must change from time to time. His finding showed that complete consistency is not always the best route.

Essentially he studied how users reacted to changes in the navigation appearance from page to page. He tested use of three versions of one site, each with a different navigation scheme. The ‘full overview’ had a full site map-like outline in the left nav, the ‘partial overview’ only listed the second and third level categories for the currently selected top level category, and the ‘local context’ listed the second level choices for the currently selected top level category plus the third level categories for the current second level category (see screen shots in the paper). Users were given directed-search tasks, or low complexity fact-finding missions.

His sample site used a ‘well-formed’ and limited hierarchy, such that each of the two upper levels’ items always had subordinates, and no item at the third level had any subordinates.

From the abstract: The results suggest an interesting pattern of interaction effects: When users are provided with partial overview navigation support, navigational volatility predicts increased disorientation, decreased perceived global coherence and decreased ease of navigation. In contrast, when provided with a more locally focused navigation scheme, navigational volatility predicts increased perceived site size and increased perceived global coherence. The results generally supported a model with a direct causal link from navigational volatility to disorientation.

Transitional Volatility: the extent to which users encounter changes in the Web interface as they move within or between sites.

On user expectations: The user becomes habituated within the recent navigation patch. The user predicts content and navigation option changes in page -to-page transitions. The user reorients at the destination page of a transition. The destination page becomes part of the recent navigation patch, continuing the cycle. So it’s just not the page right before the change that sets expectations, the user has a subtle and complex memory of pages they’ve experienced.

His incorporation of user expectations integrates the volatility question with a main challenge of navigation, the ‘behind-the-door’ problem of user’s ability to understand what a link will lead to.

On causes of disorientation: …moving among unrelated information topics in the Web space appears not to have been related to disorientation. More importantly for the purposes of this discussion, top-level switches do not, in and of themselves, cause disorientation… disoriented users consciously recognize the hyperlinks that will lead to navigational changes (navigational predictability), and then decide that such change is desirable… it was the home page link in the top-left corner of the page, just as one might have expected, that was "inviting" disoriented users, not the top-level hyperlinks.) [Spool would love this] A reasonable conclusion seems to be that the all-or-nothing nature of users’ navigational volatility distributions in the Partial Overview condition were more noticeable, and more disorienting, than the more subtle and graded changes typically encountered with a Local Context navigation scheme… The extent to which a user is habituated in a navigation patch may make the changes seem even more dramatic when they do occur

The take-away is (to oversimplify) keep navigational changes subtle. The subtlety should be in proportion to how much the user becomes habituated to the navigation. Later we see that subtle changes may themselves be helpful, assisting users in perception of connections among links.

On perceptions of site size and complexity: The study results suggest that navigational volatility leads to increased site size perception… A significant effect was not found linking perceived global coherence to perceived site size.

On perceived global coherence: navigational differences (navigational volatility) allowed users with Local Context support to see connections between distal pages they otherwise would not have seen – and so led them to view such pages as more related. Fascinating, a change in navigation actually helped the users perceive connections.

On context: The broader goal may be to precisely determine the set of factors affecting a navigator’s ability to map hyperlink attributes at a source page to characteristics of the hyperlink’s destination page. As this investigation shows, the factors will not be limited to hyperlink attributes (such as what the link’s text snippet itself says), but, rather, will extend to broader contextual factors, such as the sorts of volatile transitions the user has already been exposed to. So just looking at scent, or just shape, ain’t enough. It’s a complex interaction of several components.

Variables: he nicely controls for navigation structure and page layout. I wonder if it’s additionally possible to control for info scent and shape?

Thank you David.

Later, a comment from JJG offers a fun name for this: ‘One new wrinkle is this notion that the more navigation changes from page to page, the larger and more complex the site will be perceived to be. Call it the Seven Veils Effect: by alternately showing and hiding what’s available, you create the impression that there’s more to see than there really is.’ I’d argue that you’re just cleverly showing what’s actually there, but I love the name.

Notes on Toward Usable Browse Hierarchies for the Web (.doc) by Kirsten Risden of Microsoft Research (1999). Looking at Yahoo-style category and sampling of sub-category navigation, she seems to suggest that using polyhierarchies are a way of compensating for ambiguous categories and labels. Well yes, one might say, but if it helped people find what they’re looking for, isn’t this just an academic argument? But the point is well taken: if you’re turning to polyhierarchies to solve a findability issue than perhaps your categories (or any categories) aren’t the solution.

Thanks Kirsten.