10. Firefox opens and renders the web page including
the VP and the add-on automatically scrolls the
page to the occurrence point of the keyword of
VP query.
The pilot system limits the number of web pages
rendered to the top ten URLs of the result from Ya-
hoo! in step 5, in order to reduce the response time
from the input by the user to the output of the result.
The server side Firefox renders the ten pages to pro-
duce VPs from them. The current server has Intel
Core i7 2.8GHz and 4GB memory and the response
time is at least several seconds, at most ninety sec-
onds. The server side component uses the full func-
tion web browser with GUI to render web pages and
is on a single machine. Just a rendering engine could
be used for producing VPs instead of web browser.
Using multiple machines to parallelize the production
of VPs and caching the rendered pages are required to
improve the response time.
5 USER EXPERIMENTS
We evaluated our pilot system by user qualitative ex-
periments through three tasks for nine students. In the
first task, we designate the goal of the task, search en-
gine query, and VP query. In the second, we do only
the goal, such as “to search the article about the in-
stitute of the university”. In the third, we do nothing
and the students decide their goal by themselves. We
received the following comments:
• It is good to see the contents of web pages in vi-
sual context.
• The response time is too long.
• Effective if the information I want to know is rel-
atively clear.
• The choice of VP queries is difficult.
• It is easier to search the already known pages.
• Good size of VPs.
• The inappropriate queries produced the bad re-
sults.
These comments show that the system is useful
when the information to be searched is relatively con-
crete, or when the page to be searched is already
known in terms of its design. The inappropriate
queries produce worse result, because the number of
VPs depends on the number of the occurrences of the
VP query rather than the number of the pages returned
from Yahoo! search API.
6 DISCUSSION
6.1 Visualization vs. Space
VPs provide richer information than text based snip-
pets in compensation for the loss of space in the users’
display. In the desktop environment, it is popular to
use a large display such as over 24 inches or to use
multiple displays simultaneously, and VPs obviously
have an advantage over text based snippets.
In the mobile environment, a display of mobile de-
vices is usually not enough and a few VPs may oc-
cupy its area. Text based snippets also show only two
or three results and require users to scroll the display
in order to show more results. At that point, VPs and
text based snippets are even. When the user transfers
SERP via 3G network instead of Wi-Fi, text based
snippets may be preferable.
6.2 Contents of VP
There are positive comments to the contents of VPs.
Especially, some works described in section 2 empha-
sise only the keywords and reduce the size of the con-
tents of the web pages. As a result, we cannot read
the sentences around the keywords. Our proposal has
an advantage over them.
The range and size of VPs should be still dis-
cussed. In the current system, the keyword of VP
query is placed at the center of the VP and both the
number of pixels and the aspect ratio are determined
by experience. Actually, how to trim the web page
around the keyword would depend on the layouts of
the page. For example like blogs, the left and right
columns include the links to other dates or the pro-
file of its author, and the center one hold the body of
the blog and the comments from others. When the
keyword is placed at the left edge of the center col-
umn, the keyword should be placed at the left in the
VP rather than just the center of the VP. This prob-
lem could be resolved by identifying the layout of the
keyword in terms of DOM of HTML.
6.3 Confidence of VP
The fifth point of the comments of the user experi-
ments designates not only the effectiveness of VPs but
also the need to deal with the unknown web pages.
When the users search web pages without any expec-
tations of result, they use the titles or URLs as clues
to choose web pages in SERP. For example, if a user
finds out the specifications of a certain commercial
product, the person relies on the maker’s web site.
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