Introduction

We had users simulate visiting eight web pages using the University of Maryland Computer Science Department web site for content. The test subjects used one of two modified versions of Padprints. Both versions were identical in all aspects except for one. The first treatment allowed the subject to see only thumbnails of each visited page. The second treatment only display the title of the web page.

We have chosen the independent variables to be the visualization methods. As dependent variable, response time to answer questions, error rates, and subjective questionnaire will be used.

Hypothesis

The image treatment would yield quicker response time from the subjects. A thumbnail simply represents a smaller version of the original web page. Therefor visual cues such as large images and background colors would aid a subject in distinguishing between two web pages.

Procedure

Subjects tested individually. Before each session the subject signed a consent form. To simulate visiting web pages, we directed the user to visit eight specific web pages. This made the subject familiar with the general content of each page.

Pre-visiting the web pages also provided a time for us to cache the web pages. By caching the web pages, we eliminate anomolous delays later. We directed subjects to visit web pages in a specific order, so as to create a tree structure that is equivalent to the logical map of the web site's pages.

While the subject did this, we tutored the navigation capabilities of PadPrints. We showed subjects how to zoom in and out and the effects of pressing the 'show all' button. We especially showed them that when they clicked on a node in the history graph that Netscape reloaded that page.

The tasks were to answer 8 simple questions. These questions were design to minimize cognitive analysis and maximize navigation. A few questions follow:

• Does Clyde Kruskal have a beard?
• What time are ACM student chapter meetings?
• What is the title of the first lecture this semester?

We timed how long it took to the subjects to answer these questions? We also kept track of how many errors they made.

After the actual experiment, we asked the subject to complete a subjective questionnaire.

Finally, we gave each subject a lifesaver as a token of our appreciation.