Animated Dynamic Highlighting

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.
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