1. Introduction
The recent years have seen an exponential increase in the amount of
information available through the Internet on any given topic.
Information retrieval techniques have been steadily improving and can
provide a mass of relevant results, but those results still have to be
processed and digested by a human reader. Information professionals need technology that helps people absorb large amounts of text quickly. We introduce Animated
Dynamic Highlighting (ADH), an interactive, user-controlled technology to improve
presentational aspects of the reading task. We present the research underlying the ideas of ADH, the ADH technology
itself, and some results from an initial user study evaluating its effectiveness and
usability.
2. Background
The study described in this paper is part of a larger effort at
PARC called Productive Reading. We are looking at ways in which
computation can be applied to the reading process, in two major ways:
to enhance document content, and to enhance the user experience of
reading.
The current model of the reading interface is heavily based on the
static experience of words imaged on paper. This model has been
carried over directly to the presentation of text to the computer
screen. Some attention has been given to using computation to modify
the presentation structure of documents (Beveret al. 75-87; Walker et al.), but
with certain exceptions (Chang et al.). These presentations are
inherently static.
The major exception to this is the presentation technique commonly
known as rapid serial visual presentation (RSVP). The overview of
studies in RSVP given in Sicheritz suggest that a dynamically
altered presentation of text may be able to enhance comprehension
without negatively affecting reading speeds. However, RSVP is often
found to suffer from some serious disadvantages, notably eyestrain,
usually attributed to the fact that the user's eyes do not move from
a fixed position, and user anxiety, due to the inability to look back
at previously-read text. Other studies such as Castelhano et al. have demonstrated ways to alleviate some of these issues.
3. ADH
3.1. What ADH does
The goal of ADH is to preserve the apparent advantages of RSVP,
while mitigating the apparent disadvantages. It paces the user
through an electronic document, sequentially highlighting parts of the
text, each a few words long, without modifying the spatial layout of the original page, so that
the reader's eyes move in a normal reading fashion. The speed with which the
highlighting moves depends on properties of the chunks and on a base speed set by
the user. The reader can adjust the speed, and also restart ADH from any point in the
document. The reading speed may be at a speed somewhat faster than the
user's habitual reading speed.
3.2. The viewing technology
The ADH presentation system is part of a larger system at PARC for
archiving and reading documents, called UpLib (Chang; Mackinlay; Zellweger). The UpLib system
includes a document reader, called ReadUp, which normally supports a conventional
page-oriented document display. ReadUp was modified to present documents
in both RSVP and ADH mode.
Figure 1: A document page shown with ADH highlighting
3.3. Phrase-breaking technology
The text of a document is first annotated with part-of-speech tags
using the Inxight tagger. In
contrast to most taggers, the Inxight tool has a large inventory
of labels to distinguish between different types of determiners,
adverbs, and pronouns. While the information is less
detailed than a syntactic parser could produce, the markup makes
it possible to divide the text into semantically coherent pieces. We
have defined a large set of phrasal patterns and compiled them into
finite-state transducers (Beesley; Karttunen). The transducers are applied in a cascade
taking the output of one pattern matching step as input to the next
one. This process splits the input text into phrases proceeding from
larger constituents (sentences and clauses) to smaller constituents
(NPs, VPs, PPs) and their components. Each phrase should contain
between 2 and 4 content words (such as nouns, verbs,
adjectives, and adverbs); the boundaries of syntactic constituents are
in most cases preserved. An example of a partitioned sentence is below:
<phrase>The Marine Corps
band</phrase> <phrase>played the national
anthem</phrase> <phrase>as Dailey unveiled a
space-suited Glenn</phrase> <phrase>in his
new
place of honor,</phrase> <phrase>suspended
40 feet
above the floor</phrase> <phrase>of the
museum's
breathtaking Gallery 100.</phrase>
Finally, the established phrase boundaries are projected back to the
original source text to enable the dynamic highlighting in presenting
the text to the user.
3.4. Display timing
Each phrase is allocated an initial display time based on the
user-selected speed. This base span is then modified in a number of
ways: shorter phrases get somewhat less time, longer ones more time.
The timespan is further modified to reflect the findings in Just; Carpenter: phrases ending a line, at the end of a page, at
the beginning of a new line, or ending a sentence all receive varying
amounts of extra time, reflecting the extra time human subjects tend
to take with these kinds of phrases. Finally, the occurrence of
linguistic constructs in the phrase, such as pronouns and compound
nouns, is used to modify the timespan in additional ways.
4. User Study
4.1. Method
The goal of the user study was to assess the effectiveness of ADH and to compare
it to RSVP (Sicheritz); the same phrase-breaking
and timing were used for ADH and RSVP.
Eighteen test subjects, mostly researchers and interns, were given three alternative modes of
presenting documents: plain (not modified in any way), ADH, and RSVP. The
texts contained simple factual information and were followed by questions testing the
recall accuracy. The first stage of the experiment used documents with
automatic phrase
breaking, the second one used manual phrase breaking.
The subjects were also asked about their
reactions to the ADH and RSVP technologies.
4.2. Results
Although there were too few subjects for significant results, some
interesting trends emerged. Overall, ADH was found to be faster than
either plain or RSVP mode; it was also somewhat less accurate. In general, there was a tradeoff between speed and accuracy
in ADH: the faster a document was read, the less accurate was the
recall. However, both the speed and accuracy results were better
with manual phrase-breaking than with automatic phrase-breaking.
Users found both ADH and RSVP to be somewhat annoying, but rated RSVP worse than ADH. However, most said they
would use ADH again for skimming through short articles, especially
with improved phrase-breaking and timing algorithms. On the other
hand, most users rejected future uses of RSVP.
The lower user
ratings and reading speeds may be the result of novelty shock.
The results are nevertheless encouraging: younger subjects in
particular were very enthusiastic about ADH, and the user study produced many
suggestions for future improvements and well as possible applications of ADH.
5. Conclusion
ADH is one of the many possibilities inherent in the idea of
actively presented text. Interfaces that attempt to work with the
user in understanding the underlying text would seem to have wide
applicability for reading text of all kinds, from technical papers to
email to biography, particularly in overview reading, such as Adler's
systematic skimming and superficial reading (van Doren; Adler).
They may offer special advantages to those with reading disabilities,
or for specific tasks, such as proofreading. Our initial investigations
into this technique seem promising, and a number of improvements in
both phrase analysis and presentation timing are already being
investigated.