Enhancing User Effectiveness When Searching For ...

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he/she enters the query “parks in New York City” and receives a list of entries ... target pages link to the web pages of the Department of Parks and Recreation.
Enhancing User Effectiveness When Searching For Information On The Web Kemal Efe Center for Advanced Computer Studies University of Louisiana Lafayette LA 70504

Abstract In existing search engines, the only controls provided to users are a textbox and a search button. Once a list of search results is displayed, a user is given limited ability to explore the information space further. This paper focuses on mechanisms that allow web users to search for information in a systematic method. Components of the system in this paper include (a) Methods of display to enhance the presentation of search results, (b) A set of navigation controls for users to explore other web pages in the graph neighborhood of those pages presented in a search results list, and (c) Additional navigation controls for users to retrieve a list of pages in the graph neighborhood of the currently displayed web page in the web browser. Considered together, the set of mechanisms presented here makes up a user interface responsive to the “topic narrowing procedure” that people often use when searching for information.

1

Introduction

Recently, user interfaces of search engines have become a popular research area. A number of researchers have studied the behaviour of different user groups [1-4] in an attempt to understand the mental models of users as they search. Others [5-7] have examined the user queries in web searching. Since these researchers focused on the current practice, little insight is gained about what new navigation capabilities a search engine should offer. Spool et al observed that even when users are first taken to a particular web site that contains the desired information, they find web navigation tasks to be very difficult [9]. While academic researchers developed comprehension-based models of web navigation [10], such models have not yet been applied to the existing search engines. In existing systems, search results pages mostly consist of plain text with sentences in page descriptions often garbled up with meaningless numbers, symbols, or incomplete sentences. The overall page design is poor and monotonous, and different entries in the search result lists have similar looks and feels. These contribute to the cognitive overhead and disorientation experienced by users, leading to the “lost on the web” phenomenon [11,13,14]. In this paper, I hypothesize that user behaviour is largely driven by the set of tools made available at the user interface. With this basic hypothesis, the question becomes one of determining the set of navigation controls that should be made available to the user. In making this determination, I am focusing on what is known in two related areas: the structure of the underlying document citation graph, and the well known “topic narrowing procedure” that people often use when searching for information. It is not the ambition of this paper to advance new cognitive theories about users seeking information. Rather, it is a modest attempt to build an interface that seems to have potential to remove many of the information seeking obstacles. While many of the design decisions behind the proposed system are firmly supported by scientific evidence, due to the lack of a good reason to do things differently, there are many aspects justified by nothing more than a desire to maintain uniformity in the design. This situation testifies to the fact that designing an ideal search engine interface is a nebulous task involving numerous critical decisions. The research community is only beginning to understand the issues involved in designing effective search engine interfaces.

2

Topic Narrowing Procedure

Topic narrowing procedure basically consists of locating a source of information broader in its scope than needed, and then zooming into a narrow region that is more closely related to the topic of interest. The situation for the user of a search engine is analogous to the situation of a person new in town, trying to find a scenic park close to his/her house, preferably with a playground for children. That person could go to MapQuest.com and initially display a map of the town, and then locate different parks shown on the map. The person could pan and zoom different areas of the map to study more details of each park, and finally choose a park that has a playground and that is closest to his/her house. The cognitive process of topic narrowing happens in the mind of the person while the person is panning and zooming the map on the computer screen and studying different regions of the map. In the end, topic is narrowed from the map of town down to the map of a specific park on the map. Consider an analogy where the corpus of web documents corresponds to the terrain, and the user is searching for a desired piece of information in this corpus. Imagine a user who can only see a portion of this corpus through a window much like the case for an online map. In this case the web browser is the window, and the corpus of web documents is the terrain. The search engine maintains the “map,” i.e. an indexed database a portion of which is displayed in the window. Since the document space on the web does not support the concept of direction such as east, west, north and south, the analogous ability for panning would be achieved by giving the user the ability to move backward and forward along the hyperlinks on web pages. Zooming would be analogous to a user selecting one of the listed entries and downloading the corresponding web page for a close inspection. Now assume that instead of Mapquest.com the person in our example goes to the web site of a search engine. There he/she enters the query “parks in New York City” and receives a list of entries displayed in a search results page. Some of these entries may refer to national parks outside the city limits, some may refer to unrelated sites (e.g. the Park Hotel in New York City), but a few may refer to related sites, such as the home page of the city’s Department of Parks and Recreation. Now the user selects the home page of the Department of Parks and Recreation (a choice he/she hadn’t though to search for initially) and retrieves a wealth of information from maps and pictures of facilities, to a calendar of scheduled activities for several parks in the city. The user can now explore different parks in detail and determine which one he/she likes best. Exploration is an essential tool for navigation. Although users may identify a rewarding link toward the desired information when they see it, they are seldom in possession of a specific idea about the source of information they want. In the above example our user has been lucky that the entry for the home page of the Department of Parks and Recreation was among the listed search results. It may not have been there. Instead, there may have been other entries whose target pages link to the web pages of the Department of Parks and Recreation. If that were the case, the path from the search results page to the desired information would be a challenging one. To a large extent, the level of control explicitly made available to a user drives a user’s curiosity. The user could try a few of the initially displayed entries and give up in frustration when he/she cannot find the desired information readily displayed. Provision of effective navigation tools is essential for users to discover information that the search engine has not readily displayed.

3

Proposed Model

The proposed model aims to satisfy the comprehend + explore=navigate formula that appears to have the greatest potential for responding user needs. A key claim of Kitajima’s work [10] is that comprehension of texts and images is the core process underlying web navigation. An enhanced presentation style that eases users’ comprehension overhead is therefore a prerequisite for any interface between a user and a search engine.

3.1

Reducing the Comprehension Overload by Images

A picture is worth 1000 words. To alleviate users’ comprehension overhead, images can be included in listed entries of search results to help distinguish, recognize, and retain different entries. While this suggestion may appear be obvious, it is possible to use images in a way that does not help users with the problem of comprehension overhead.

For example, Froogle.com displays product images in its search results entries. In response to a query, say “greeting cards,” the displayed search results contain greeting card pictures associated with each entry. Since different greeting card pictures on the web page look alike, except when inspected in detail, the user’s ability to comprehend and discriminate different entries is not enhanced much. Other search engines such as Netscape.com and Alexa.com display thumbnail images of target pages. But, the thumbnail images merely reduce the components of a web page to a random-looking silhouette with no meaningful mental imprint for the user to hook. What kind of images would then serve the users’ needs better? Enough evidence exists to argue that besides helping comprehend and distinguish different entries from one another, the images should convey information about the person or organization that owns the web page represented by each entry. In a recent test [15], users’ navigation paths gravitated toward their perceived sources of credible data. Most test subjects tried to understand the source of information by inspecting the URL data provided before they pursued the associated link. These observations imply that users would prefer seeing representative images such as company logos or other identifying marks of web page owners instead of generic pictures that don’t identify the source of information. For example, in a search results entry for Hallmark, the company logo of Hallmark should be displayed instead of a sample greeting card manufactured by Hallmark. For the web page of a scientific document repository, the logo of the scientific organization that owns the web page would be representative. For a personal web page, a photo of the person who owns the web page would be representative. For a page with no logos or trademarks, the graphics at the page title can be used to represent the page. Beyond a logo, which is usually a still image, one can easily imagine additional capabilities included in an entry such as an animated image, video or audio to further enhance the user experience and reduce comprehension overhead. Web page owners will be glad to provide such images to a search engine if they are asked, since inclusion of images will enhance the visibility of their entry on a search results page.

3.2

Display Structure

As mentioned in Section 2 above, the navigation model proposed here is based on tracing the edges of an underlying graph structure. A relevant question to consider is what method of display to use on a search results page so that users can effectively trace the graph structure of the web. There are commercial search engines such as Kartoo.com as well as research prototypes such as Lighthouse [16] that represent the underlying information space in a graphic display. While these graphic tools are useful for visualising the relationships between documents that the search engine has returned, they offer no help in navigating toward documents that the search engine has not returned in response to the user query. There are many reasons why valuable information sources may be absent in a search results page such as misclassification, poor ranking, and poor crawling performance. The method of display should allow and encourage reaching documents not originally displayed on the search results page. From the ergonomics point of view, users need not know that they are tracing the edges of an underlying graph structure, or even that they are navigating a graph structure. Graphs or other mathematical representations may not appeal to users with insufficient analytic inclinations to interpret or comprehend the displayed graphics (and this includes majority of potential users). The resilience of the classical “results list” display style used by commercial search engines is evidence that a list format is relatively more agreeable by most search engine users. Besides, useful information carried by text is often difficult to codify in a graphic display. Until evidence is found to the contrary, it is safe to assume that users are comfortable with the “result list” style of presentation. What is necessary is then to enhance this display format for easy comprehension and navigation. In the proposed system, display structure of a listed entry is a template that contains the components 1-6 below (see Figure 1). Item 7 is associated with web pages rather than search results pages. 1.Title: This is the title of the entry, which is text that briefly presents the corresponding web page, typically in one line. The title is associated with a hyperlink that retrieves the corresponding page. 2. Multimedia Object: An image such as a company logo, which itself may be ornamental text, or some animate or inanimate figure. The image may be still or animated, with or without sound. The multimedia object may be associated with a hyperlink that retrieves the corresponding page.

3.Description: A brief summary description of the corresponding page, typically 5-30 words. Description may use language designed to entice viewers to visit the corresponding web page. Different parts of the description may contain separate hyperlinks each retrieving different web pages from the same site, or starting the display of a web page at different parts of a page.

4. Target URL: Text that presents the URL, which the network uses to uniquely identify and retrieve the target page. 5. Backward Panning Controls: At least one or both of: a. A selectable control that retrieves a list of pages that link to the target page. b. A group of selectable controls each capable of retrieving a page that link to the target page. 6. Forward Panning Controls: At least one or both of: a. A selectable control that retrieves a list of pages that are linked to by the target page. b. A group of selectable controls each capable of retrieving a page that is cited by the target page. 7. Three selectable controls associated with web pages that move a surfer from the “document space” to the “index space” as will be explained. According to this model, the components 1-6 constitute the template for a listed entry on a search results page. These components must be structured in a method of display that is easy to comprehend and that makes each component easy to locate and select. One possible design is shown in Figure 1. Item 7 above specifies three additional navigation controls, exemplified in Figure 2. These control buttons can be included in a frame or in a toolbar associated with the web browser.

3.3

Underlying Mechanisms

To understand the operation of the underlying mechanisms, it is useful to consider the web graph, where the nodes of the web graph represent the web pages and the edges of the web graph represent the links on web pages. An edge is drawn in the web graph from a first node representing a first web page to a second node representing a second

web page if the first web page contains a hyperlink that specifies the second web page as its target URL. Let us call this graph the “document space graph,” or DSG.

A search engine that indexes web pages and analyses the hyperlinks contained in web pages also saves metadata about each web page. A portion of this metadata comprises what is displayed about a web page when the page is included in a search results page. Consider a graph whose nodes correspond to these metadata items, and the edges of the graph are copied from DSG. In particular, if there is a hyperlink on the page A pointing to page B, the search engine creates an edge from the metadata item of A to the metadata item of B. I call this second graph the “index space graph,” or ISG. Figure 3 illustrates ISG and DSG. DSG is an abstraction from the physical world, and nobody knows what it looks like exactly. Owners of web pages participate in constructing it: whenever a web page designer launches a new page on the Internet, he or she adds a new node and its associated outgoing hyperlinks to DSG. On the other hand, the search engine constructs ISG by creating its nodes based on web pages it has crawled and indexed, and by copying its edges from DSG. Typically, ISG is much smaller than DSG. As shown in [8], even the largest search engine in the marketplace is able to index a small fraction of existing web pages. The set of nodes of in ISG represents the pages that the search engine has been able to index. Also, when copying the edges from DSG to ISG, it is not required to copy all the edges found. Only the “important” edges may be copied according to some criterion set by search engine operators. Another important difference between the two graphs is that edges in DSG are directed in only one way from the citing page to the cited page. These one-way citation edges allow a surfer to “move” from a citing page to a cited page, but not in the opposite direction. In ISG, all edges are directed both ways to allow moving between two nodes in either direction with equal ease.

When a surfer A is looking at a web page, he/she is really looking at a node of DSG. When a surfer B is looking at a search results page, he/she is really looking at a set of nodes drawn from ISG. The surfer A can only see one document at a time while the surfer B can see several listed entries simultaneously. This situation is analogous to inspecting a map in two levels of scale. The larger scale map shows a wider geographical area with less detail. Similarly, the surfer looking at the nodes of ISG can see several pages with less detail of the information about each page.

Just as a user surfing the web goes from one node of DSG to another by clicking on the hyperlinks on web pages, a similar user in ISG can be given the corresponding tools to surf the index space graph. Initially the surfer starts by entering a search query and retrieves from the search engine a first list of entries displayed on the computer screen. Once the first search results page is displayed, the surfer can surf on ISG by using the forward panning control (display component 6.a) or the backward panning control (display component 5.a) associated with a desired entry. The forward panning control 6.a retrieves a list of pages cited by the target page of an entry. The backward panning control 5.a retrieves a list of pages that cite the target page of the entry. The surfer can also switch between the two graphs at will; using ISG for a coarse level resolution of the broad topic being searched, and DSG for the finer levels of resolution. After the surfer has located an entry in the index space graph that looks like its corresponding web page might contain the desired information, the surfer can retrieve the corresponding page by selecting the corresponding hyperlink in the listed entry, thereby moving from ISG to a page in DSG. Alternatively, when moving from the ISG to DSG, the surfer is provided with an option to select one of the graph neighbours of the target page in DSG. Choosing one of the icons in component (6.b) of the entry retrieves a

page cited by the target page of the entry. Choosing one of the icons in component (5.b) retrieves one of the pages that cite the target page of the entry. Having moved from the index space graph to the document space graph, if the target page contains the desired information, the surfer is satisfied. Otherwise, the surfer can surf on DSG until desired information is found. If the surfer is not satisfied with the information found, the surfer can switch to ISG back again. The three selectable controls in item (7) allow a surfer to move from a web document up to ISG. When making this move, the surfer is provided with three possible options (see Figure 2): Display a list of related or similar pages (related or similar to the page currently displayed in the browser), or display a list of pages that cite the current page, or display a list of pages cited by the current page. When the user clicks on the “similar pages” button, the web browser containing the currently displayed page sends the URL of the currently displayed page to the search engine with a request for a list of similar pages. It is important to make sure that the returned list contains an entry for the page itself, to allow exploring the graph neighbourhood of the page in ISG by using the selectable controls of items (5) and (6) for its entry. When the user clicks on the “Cited by” button in Figure 2, again the web browser containing the currently displayed page sends the URL of the currently displayed page to the search engine with a request for a list of pages that cite the currently displayed page. Finally, when the user clicks on the “Links to” button in Figure 2, again the web browser containing the currently displayed page sends the URL of the currently displayed page to the search engine with a request for a list of pages cited by the currently displayed page. In all these cases, when the search engine responds with the requested list, the list can be displayed either in the same browser window or in a separate browser window.

3.3.1 Backward Surfing The selectable control specified in 5.a allows a surfer to move “backward” on ISG. The importance of this facility can be better appreciated by considering scientific citations where related documents are often cited together. If one is interested in learning about water pumps and one has already found a first document on the subject but needs more information, it would be beneficial to find a document that sites the first document. The citing document may contain the desired information, or it may cite a third document containing the desired information. I am not the first researcher to observe the potential benefits of being able to surf backward. A recent paper [19] presents an interesting discussion about social aspects of such a capability along with methods of implementation. Similar facilities are available in various forms at some of the existing search engines such as Google.com and HotBot.com. Hyperlink databases such as Atlas [18] can provide the needed information for discovering backward links not available at a search engine. A client-side tool can combine the search results of a search engine with the services of a hyperlink database. Such a combination could augment the users’ reach to online information significantly as it would allow reaching other sources not yet indexed by the search engine. This is especially useful because the commercial search engines only index a small fraction of existing web pages. In addition, different web pages listed in a search results page tend not to cite one another due to competition or other reasons for conflict of interest, or simply due to lack of awareness or motivation. For example, web pages of Dell do not link to web pages of IBM, or vice versa. This phenomenon manifests itself in the formation of bipartite components as shown in Figure 4. [17]. In such a bipartite component, a set of “fans” link to a set of “authorities.” Authorities are the pages with authoritative information, and fans are the pages that cite them. This phenomenon is so widespread in the web graph that successful link analysis techniques used by search engines depend on discovering the bipartite graph pattern partially (in the case of PageRank algorithm [20]) or completely (in the case of HITS algorithm [21]). Still, these algorithms have their shortcomings. For example, while PageRank algorithm is most likely to display authority pages, it has no built-in component to guarantee that all authority pages are found. HITS algorithm tries to find all the authority pages and fan pages, but it suffers from the “topic drift” phenomenon. We gave a detailed discussion of these issues in a recent paper [17], so I will not elaborate on them further here. The proposed tools have the potential to compensate for these shortcomings of existing algorithms. Normally, a search results page responsive to the user query “computer manufacturers” should contain entries for both Dell and IBM since they are both worldwide authorities on the subject, but if one of these entries is missing on a search results page, a user of the search engine should still be able to reach the missing page. This would be possible if a user could move backward from an authority page to a fan page that cites both pages. Once a user is at a page that

cites both Dell and IBM, he or she would be able to follow the forward links to reach the authority page that was missing in the initial search results list.

Although it is possible to surf the ISG backward indefinitely, due to “focus disintegration,” it may not be very fruitful to make multiple backward moves away from an authority page. To understand this concept, consider an authority page that is highly relevant to a user query. Consider a fan page that cites this authority page. Due to an analogy with scientific citations where a citing document is often on the same topic as the sited document, we expect that the information in the fan page would be related to the information on the authority page. On the other hand, the concept of “related to” is not necessarily transitive. As we move further away from a first authority page by following a chain of backward links, the topic tends to change, and its original focus tends to disintegrate. Consequently, the relatedness with a first page weakens more, as one moves further away from the first page. For this reason, if the search engine sending the initial list of search results has done a good job of finding pages related to the user query, then the required information can be found either in the set of initially listed pages, or in their immediate graph neighbourhoods.

3.3.2 Forward Surfing The selectable control specified in 6.a allows a surfer to move “forward” on ISG. In particular, selecting the control (6.a) associated with a listed entry causes the display of a list of web pages that are cited by the target page of the associated entry. One can consider the utility of this component as one that creates a “bibliography” list for the target page of the selected entry. This allows users to quickly browse several cited pages at once at a low level of resolution in terms of information content displayed. While a surfer can follow these ISG links forward indefinitely, due to the focus disintegration phenomenon mentioned above, a user is more likely to find the required information within a few links of the initial search results page rather than far away. Combined with the facility of (5.a), a surfer can also surf the ISG in a zigzag path, going forward and backward. We note that due to bipartite pattern of related pages, such zigzag paths are more likely to be fruitful than all forward or all backward paths.

3.3.3 Zooming Zooming is achieved by moving from ISG to DSG, which, in effect, expands the level of detail displayed in the information space. Existing systems only support moving from a listed entry to its corresponding web page. In addition, the proposed system allows reaching other nodes in the graph neighbourhood of the listed entry directly from ISG.

3.3.3.1 Switching From ISG to DSG The group of selectable controls in (5.b) represent web pages that cite the target page of the listed entry. Selecting one of these controls allows a surfer to move from the ISG directly to a page that cites the target page of the listed entry. This facility could be useful if the surfer recognizes the icon representing the citing page. The utility of including the controls in (5.b) may appear to be limited in the presence of the control in (5.a), because by first surfing on the ISG backward from a node, and then by selecting a page in the second list, one can reach the same pages reached by these controls. The benefit is non trivial, however, because associating the icons of citing pages with the entries of cited pages makes the citing pages readily visible for the benefit of the viewer. The group of icons in (6.b) represent web pages that are cited by the target page of the listed entry. Selecting one of these controls allows a surfer to move from the ISG directly to a page that is cited by the target page of the listed entry. This facility could be useful if the surfer recognizes the icon presenting the cited page when inspecting the listed search results. The benefit of this facility is non trivial, because associating the icons of cited pages with the citing pages makes the cited pages readily visible for the benefit of the viewer. There are design choices that need to be made when adding the set of selectable controls in (5.b) and (6.b) within the template of a listed entry. One issue relates to the number of icons to be included. It will be appreciated that the number of pages that cite (or cited by) a page can be very large. Since only a few icons can be included in a display, the interface needs to choose a small subset of this set for display. This choice may be made by any criterion including, but not limited to the popularity of the citing page, or its similarity with the target page of the entry, etc. The second issue relates to the appearance of the icons presenting the citing/cited pages. Their purpose of display is secondary to the purpose of displaying the main entry; therefore their display must be less prominent than the display of the main entry to reflect their comparative status. As exemplified in Figure 1, a smaller representative image may suffice for the purpose. If a representative image is not available, a hyperlink associated with underlined text may be used.

3.3.3.2 Switching From DSG To ISG The three selectable controls specified in item (7) allow moving from a node of DGS to a search results list derived from ISG analogous to zooming-out on a map to cover a larger terrain. The first of these selectable controls retrieves a list of pages that are “related to” or “similar to” the page currently displayed in the web browser. Existing search engines such as Google.com and Alexa.com provide “similar pages” links associated with search results entries. However, as of the date of writing this article, there is no facility to retrieve a list of “similar pages” while viewing a page itself. The second of these selectable controls retrieves a list of pages cited by the current page and the third one retrieves a list of pages that cite the current page. As the currently displayed page is a web document and not a search results page, the surfer is currently at a node of the DSG. Selecting this control “moves” the surfer from a node in the DSG to the ISG such that several nodes of the ISG are displayed in the web browser. The benefits of these components are apparent as one considers the benefits of the corresponding components in (6.a) and in (5.a), and hence I will not elaborate on them further.

4

Conclusions

The mechanisms for surfing the web in two levels of detail as described here are now being implemented at http://www.ChaBook.com. This model is inspired by the known underlying graph structure around authoritative web pages as shown in Figure 4. The main goal of this project is to give users enough control so that they can trace the graph edges backward and forward so as to reach all the pages included in a bipartite graph pattern. While one may be tempted to try and display the graph itself, I have taken a more conservative approach by trying to keep the displayed information in the more traditional “result list” style. It is possible that augmenting this display style with some form of easily comprehensible graphic display could add to the user’s sense of orientation. We are currently investigating alternative ways to display such information.

As mentioned throughout this paper, various components of the model presented here are already available in one form or another at various search engines. It is, however, more important to have them as integral parts of a comprehensive scheme rather than as fragmented features, because it is possible to provide the right components in a wrong way when the motivation for the provided component is not guided by a higher purpose. The product images contained in search results entries of Froogle.com exemplify this. Even if it turns out that only a subset of the proposed components are truly useful, it is better to have a meaningful higher purpose for having them so that they can be implemented in the most useful way possible for the users.

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