Masters Thesis - Issues of Saliency and Recognition in the Search for Web Page Bookmarks
2. Purpose of the Experiment
2.1) Rationale for studying text-only bookmarks
Bookmarks are a convenient way to revisit web pages, until your bookmark list grows so large you can no longer find the bookmark you need. This task becomes even more difficult when returning to the list after a long time, most likely with a fragmented memory of what the bookmark text actually was.
To address these problems, there has been a lot of productive research in making bookmarks easier to find and organise (Cockburn & Greenberg, 1999; Cockburn et al., 2003; Kassten, et al., 2002; Abrams, Baecker & Chignell, 1998; Tauscher & Greenberg, 1997). Custom icons can make the bookmark reference stand out, as shown in Figure 6.
Figure 6
Custom icons can make bookmarks easier to spot.
An extension of this idea is the use of thumbnail images of the websites themselves next to the text bookmark, as in Figure 7. This has been shown to be a successful approach (Cockburn, et al., 2003), but is yet to adopted by Internet Explorer as a standard revisitation mechanism.
Figure 7
Thumbnail images of web sites next to their text bookmarks can aid recognition (Figure Cockburn & Greenberg, 1999).
The research states that there are severe limitations to using the <title> tag text for bookmarks, as mentioned in the previous section (Kassten, et al., 2002; Cockburn, et al. 2003). However, these 'limitations' are not inherent in the <title> tag system, but stem from Web producers' own habits. Icons are subject to the same limitations, since they are also created by Web producers. Some of these icons can be rather obscure and may not in fact aid recognition of the bookmark.
Furthermore, the advantages of icons may be short lived. If the use of custom icons becomes widespread, and every bookmark has one attached, their 'pop out' value will be greatly reduced and recognition time is likely to be just as slow as it can be for text.
Thumbnails also have their own recognisability problems. Text-based pages are hard to recognise at any resolution and pages from web sites that are consistently designed are hard to differentiate (Cockburn & Greenberg, 1999). Thumbnails also consume a high proportion of screen real-estate. Each bookmark on the favorites menu in Internet Explorer occupies 20 pixels of vertical space, however, to achieve just a 60% chance of recognising a particular web page, a thumbnail 144 pixels high is required (Kassten, et al., 2002).
Accessibility and usability may also be problematic for visual recognition aids. Icons and thumbnails are of little to no benefit for visually impaired users, but plain text can always be interpreted by voice web browsers. Similarly, other systems such as file organisers, search engines and databases may not be able to interpret graphical representations. For example, it may be difficult to implement automatic and meaningful bookmark sorting based on graphical properties.
In terms of usability, it is not clear if icons and thumbnails will transpose well to PDAs and mobile phones. These devices have extremely limited screen real-estate, and thumbnails in particular may have to fill most of the screen in order to be recognised.
The research has shown that these visual aids can make bookmarks stand out, but this same research does not propose how to make web pages easier to recognise when they are represented by standard text-only bookmarks.
It is clear that text-based referencing is still a major force on the Web and warrants continued research and improvement. This study is intended as an initial step towards this aim by finding the factors that most affect the recognition of text bookmarks.
2.2) Types of bookmark: Top-down & Bottom-up structures
Most web producers use their common sense when writing bookmark text. They ensure that the text satisfies some basic criteria, then choose some appropriate information to identify the page, such as the name of the website or the subject of the page, etc. (Table 1).
| Identifying information |
|---|
|
They then have to choose how they will put this information together.
Many web producers who manage large websites with several levels of information choose to model the <title> tag text on how this information is organised on the site. This can help users while they navigate, because their navigation trail is built up in a logical way, giving them feedback on where they are, and how they got there, as shown in Figure 8 (Preece, Rogers & Sharp, 2002).
Figure 8
The navigation trail through a website can be shown in the browser's top bar
Two common ways of describing these information structures are 'top-down' and 'bottom-up' (Rosenfeld & Morville, 2002). A top-down structure may list the name of the site, followed by one or more sections and finally the title of the page (Table 2).
| Model: | site name - section name - page title |
|---|---|
| Examples: | BBC NEWS - Middle East - Top Saddam official surrenders Lancaster University - Postgraduate students - Alex Poole |
Conversely, a bottom-up structure starts with the title of the page, and ends with the name of the site (Table 3).
| Model: | page title - section name - site name |
|---|---|
| Examples: | Top Saddam official surrenders - Middle East - BBC NEWS Alex Poole - Postgraduate students - Lancaster University |
Both structures could reasonably identify a page, but how do we know which one will be most recognisable to users when they are searching in a large list, with imperfect memory?
2.3) Saliency and recognition
The assumption for the present study is that the information at the start of the bookmark is somewhat dominant. The leading information defines the structure of the bookmark - if it starts with the title of page, it must be bottom-up, and if it leads with the name of the site, it must be top-down.
Also, the leading information has a higher 'profile' as users tend to 'scan' down the left-hand side of a menu (Altonen, Hyrskykari & Räihä, 1998), sometimes only reading the first word or two of each list item.
Bearing this in mind, if there is a difference in saliency between the title of the page and the name of the site, this should affect the salience of the bookmark as a whole.
The second assumption for the present study is that the page title is likely to be more salient than the site name, meaning that bottom-up structures may be more salient than top-down structures. There are several reasons why this might be so.
Firstly, users actions are driven by goals and tasks (Preece, et al., 2002). Visually searching the bookmark menu is an example of goal-driven behaviour - the user is searching the menu to find a particular bookmark, for a particular reason. Anything that is tailored to the user's task will improve the usability of the system (Nielsen, 1992). Since the title of the page describes what the user was specifically reading, while the site name may be completely unconnected to the subject matter, it is likely that the page title may fit the user's task more than the name of the site, improving relevance and potentially improving recognition.
Secondly, the fuller descriptions afforded by page titles may be more likely to evoke stronger mental imagery, which is known to aid memory and recognition (Clark & Paivio, 1987). Likewise, they may fit better into our existing knowledge structures, aiding subsequent recognition (Alba & Hasher, 1983; Bartlett, 1932).
The final assumption is that the number of components in the bookmark is likely to affect recognition. The more pieces of information that are displayed, the more we will able to infer the meaning or identity of the whole bookmark. The possible interpretations are constrained by the context brought by the extra information (Rumelhart & Norman, 1985).
Measurement
In the present study, recognition will be measured by the time taken to find a target bookmark embedded within a set of distractor bookmarks. Faster times will be taken as indicating superior recognition.
Eye movements will also be used as a measure of information salience: In particular, the number of fixations on a bookmark component, together with fixation duration, will be taken as an index of relative salience. A detailed justification for using eye movements is provided in section 3. Suffice it to say that the use of eye movements in the present study is based on the assumption that they provide an on-line measure of the processing demands associated with items of information, such that more processing would reflect decreased salience and less processing would reflect improved salience.