An Exploration
Advanced Types
Beyond standard location, path, and attribute breadcrumbs, two particular examples illustrate more advanced applications for this type of navigation: selection list navigation bars and look-ahead breadcrumbs.
Selection List Navigation Bars
Bowler et. al. (2001) developed and tested a modified version of breadcrumb navigation called "selection list navigation bars". With this kind of navigation, a user can pull-down any element to link not only to higher pages in a site's hierarchy, but also to all of those pages' siblings.
Source: http://www.otal.umd.edu/SHORE2001/navBar/index.html
Look-Ahead Breadcrumbs
Blustein et. al. (2005) tested look-ahead breadcrumbs versus standard static breadcrumbs. Look-ahead breadcrumbs are very similar to selection list navigation; they reveal a list of links reachable from a breadcrumb item.
Source: An evaluation of look-ahead breadcrumbs for the WWW
Discussion
While neither of these methods is used prevalently on the Web, the results of these studies are encouraging. Blustein et. al. found that 92% of their participants expressed a preference for look-ahead breadcrumbs over the standard method, and 60% of those participants said look-ahead breadcrumbs made navigation easier for them. Bowler et. al. found that their participants performed worse with the selection list navigation during the first half of their task list, and as they progressed through the experiment, they learned how to best use the new navigation. By the second half of their tasks, participants found more success using selection list navigation over the standard breadcrumbs.
Participants in Blustein's study were educated about the breadcrumbs before the experiment and used them successfully, and those in the study by Bowler et. al. found more success with their selection list navigation than the standard breadcrumbs while completing the second half of their tasks. Thus, both studies corroborate Hull's research (2004), which revealed that users are much more likely to use breadcrumbs to their advantage if they are educated about the nature and purpose of breadcrumbs before performing their information retrieval tasks.