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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Detecting reading strategies during task-oriented reading: Building an automated classifier</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>George Kachergis∗</string-name>
          <email>G.Kachergis@donders.ru.nl</email>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Jolique Kielstra∗</string-name>
          <email>J.Kielstra@pwo.ru.nl</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Lars Bokkers</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Bellamie Persad</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Inge Molenaar</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Behavioural Science Institute, Department of Educational Sciences, Radboud University</institution>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Behavioural Science Institute, Department of Educational Sciences, Radboud University</institution>
          ,
          <addr-line>Nijmegen</addr-line>
          ,
          <country country="NL">the Netherlands</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Department of Artificial Intelligence, Radboud University</institution>
          ,
          <addr-line>Nijmegen</addr-line>
          ,
          <country country="NL">the Netherlands</country>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>Donders Institute for Brain</institution>
          ,
          <addr-line>Cognition, and Behaviour</addr-line>
          ,
          <institution>Department of Artificial Intelligence, Radboud University</institution>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2018</year>
      </pub-date>
      <abstract>
        <p>Secondary school students are continuously asked to read texts and execute tasks related to these texts. Many students experience dificulties in reading to successfully perform these tasks. Taskoriented reading is conceptualized as an adaptive problem-solving process in which readers engage with the text selectively based on the task. Usage of appropriate reading strategies leads to more eficient and accurate task performance. Our aim is to provide students with personalized support to efectively select reading strategies. A first step towards personalized support is the automatic detection of students' reading strategies. This study describes the development of a supervised machine learning classifier to detect students' reading strategies. Human raters classified 1,091 graphs of students' behavior recorded on tablets as they engaged in taskoriented reading. These ratings were used to train a classifier on 13 features extracted from the students' reading behavior. The overall accuracy for classifying reading strategies was 0.74, significantly greater than chance. Searched reading strategies were the easiest to identify, with a balanced accuracy of 0.84, followed by intensive (0.81) and targeted reading strategies (0.69). The most important features in the classifier were the ratio of sentences that readers skimmed too quickly, the number of unique sentences read, and the variance of time spent reading each sentence. These features are quite diferent from typical process variables used to study taskoriented reading, yet are easy to automatically extract in tabletbased reading. This classifier is a first step in the development of personalized support based on students' use of reading strategies.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>∗Equal contribution.
reading strategies, task-oriented reading, automatic classifier
Permission to make digital or hard copies of part or all of this work for personal or
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For all other uses, contact the owner/author(s).</p>
      <p>PALE’2018, June 2018, London, UK
© 2018 Copyright held by the owner/author(s).</p>
    </sec>
    <sec id="sec-2">
      <title>INTRODUCTION</title>
      <p>
        Task-oriented reading involves reading with the purpose of
processing information for the execution of a specific task [
        <xref ref-type="bibr" rid="ref2 ref27">2, 27</xref>
        ]. During
task-oriented reading, students must do more than read and
comprehend the text: the focus is on executing the task connected to the
text. Thus, students need to appropriately understand the task and
select a reading strategy aligned with the task [
        <xref ref-type="bibr" rid="ref27 ref28">27, 28</xref>
        ]. The RESOLV
model [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ] puts students’ task representation in a central position
to explain strategy selections students make. Prior to reading, a
task can act to signal relevance, allowing readers to understand
which sections of the text are relevant for the task [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ]. This allows
students to select a reading strategy that supports successful
accomplishment of the task [
        <xref ref-type="bibr" rid="ref21 ref22 ref29">21, 22, 29</xref>
        ]. Diferences in tasks induce
diferent reading strategies. For example, simple tasks ask students
to locate the needed information in the text with a search strategy,
whereas complex tasks, that require integration of diferent parts
of the text, elicit intensive reading [
        <xref ref-type="bibr" rid="ref22 ref5">5, 22</xref>
        ]. Reading strategies are
methods students use to understand and process information
presented in a text. Decision-making regarding which reading strategy
to apply depends on student characteristics, task objectives and
text objectives [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. In summary, task-oriented reading is the ability
to successfully create a task representation in order to select the
most appropriate reading strategy for a given task [
        <xref ref-type="bibr" rid="ref10 ref9">9, 10</xref>
        ].
      </p>
      <p>
        Task-oriented reading research shows that task performance
is influenced by how students apply reading strategies [
        <xref ref-type="bibr" rid="ref13 ref2 ref7">2, 7, 13</xref>
        ].
For example, Rouet and colleagues [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ] showed that diferences in
students’ reading comprehension can be explained by their
application of reading strategies during task execution. Previous research
indicates that proficient readers tend to use more diverse reading
strategies compared to less proficient readers [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ], and that they
apply these reading strategies more frequently [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ]. Less proficient
readers, such as students in vocational secondary education,
experience dificulty in applying reading strategies that support successful
task execution [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. They often resort to two diferent compensatory
approaches during task-oriented reading. Either they start reading
a text before developing a task representation or they immediately
start with task execution by scanning the text before reading [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ].
Moreover, less proficient readers tend not to change their approach
and reading strategies even when they prove to be unsuccessful,
whereas more proficient readers adapt their approach to changing
perceptions of task execution [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ].
      </p>
      <p>
        Thus, in order to enhance successful task-oriented reading, less
proficient students need help in task understanding, strategy
selection and applying reading strategies to fulfill their tasks [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. In
order to support students selection of reading strategies, it is of
great importance to detect the actual reading strategy students use.
The automatic detection of reading strategies can guide the
development of interventions to improve students’ task-oriented reading.
Although ample research provides evidence for the importance of
reading strategies during task-oriented reading, it does not inform
us how students’ apply these reading strategies. An increased
understanding of how students’ select and apply reading actions and
how these form reading strategies is needed to further understand
reading as an “adaptive, problem-solving process whereby readers
engage with text selectively based on their self-generated goals and
plans” as stated by Rouet [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ]. Automatic detection of reading
strategy used during task execution could help develop advanced forms
of support for students. Below we discuss how reading strategies
are currently measured.
1.1
      </p>
    </sec>
    <sec id="sec-3">
      <title>Measurement of reading strategies</title>
      <p>
        Generally we see three diferent approaches to the measurement of
students’ reading strategies. First, researchers have used computers
to measure students reading time. Students click to receive the
consecutive sentence, allowing researchers to record the reading
time per sentence [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ]. These measurements are typically used to
assess how relevant instructions afect the reading time of
relative sentences. Second, think-aloud procedures are used, in which
students are asked to read aloud and also verbalize their thoughts
while reading [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. This method is used to understand how students
regulate during reading. A special approach of thinking aloud is the
bridging method, in which students are asked at a regular interval
(e.g., every 2 minutes) to indicate what they are thinking. Based on
these utterances, researchers analyze how and which inferences
students make during reading [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ]. Third, reading research has been
using masking as a means to follow how student read a text [
        <xref ref-type="bibr" rid="ref27">27</xref>
        ].
Task-oriented reading processes are measured with a tool called
Read&amp;Answer, by masking the text, with the exception of a text part
deblurred by the student. This procedure allows Read&amp;Answer to
capture how students read a text. So far these data have been used
to derive a number of process variables which are informative of
the student’s reading process. Both regulation and reading indices
are derived. Examples of the indices are time for initial reading of
the text, number of rereadings during initial reading, and number
of search decisions.
      </p>
      <p>
        The above-described online measurements of the reading process
can all be classified as variable-based approaches, which uses online
data to construct variables as indicators of particular reading actions
such as the number of search decisions or the time spend on relevant
text. These variable-based approaches focus on the analysis of
variance between independent and dependent variable(s), such as
the association between search decisions and task performance [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ].
Variable-based approaches mainly focus on reading actions, such as
rereading, time spend on task and monitoring decisions by checking
the text [
        <xref ref-type="bibr" rid="ref13 ref7">7, 13</xref>
        ]. In contrast, event-based approaches analyze the
(dynamic) relations between events [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ]. Researching the nature of
relations between events and their development over time is central
in this approach. For example, such an approach can indicate how
diferent reading actions together form a reading strategy. This
allows for insights into temporal characteristics of reading actions,
as well as how diferent actions interplay over time and form a
reading strategy. Consistency and change in reading actions can
be investigated by specifying these temporal characteristics [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ].
It is important to emphasize that event-based approaches are a
deviation from the traditional research paradigm used in prior
reading research [
        <xref ref-type="bibr" rid="ref19 ref24">19, 24</xref>
        ].
      </p>
      <p>
        A clear distinction can be made between two dimensions of time
that are useful for the field of reading research, i.e. focusing on
individual events within the continuous flow of events or relative
arrangements of multiple events (Molenaar &amp; Wise, in prep). So
far, when using online data, mainly frequency analysis indicating
the number of occurrences of a variable during a particular time
window are used. This provides insights into the prevalence of a
particular reading actions during learning. For example, Rouet et
al. [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ] found that tasks that demand explicit information from a
text elicit more rereading among students. This analysis showed
the significance of rereading, however we do not know whether
the position of these actions in the reading process matters, nor
if the duration of these actions or the rate at which these
rereading actions occur during reading matter. Thus frequency analyses
treat the reading process as one holistic unit, ignoring the
individual time-related characteristics of variables. However, the first
dimension of time, ‘individual events within the continuous flow
of events’, captures how variables behave by examining the
individual time-related characteristics of events within the flow. These
individual time-related characteristics can illustrate how events
occur within the flow of continuous events in a particular time
window by analyzing the significance of the position of events,
the duration and rate at which particular events occur within the
reading process. For example, poor readers reread the task more
often when they are reading the text, while more proficient readers
spend more time initially reading the question before reading the
text and less time rereading the question when reading the text [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ].
      </p>
      <p>
        In contrast the second dimension of time, ‘the relative
arrangements of multiple events in time’, focuses on how events are
organized among each other. An example is how the combination
of multiple reading actions form an arrangement that can be
recognized as a reading strategy over diferent settings. The second
dimension of time conceptualizes how reading actions behave in
relative arrangements of multiple events by examining the
organization of these actions. For example ‘Low-level’ questions that focus
on retrieving a single concept and demand for little inferencing
often initiate a search strategy referred to as “locate-and-memorize”
[
        <xref ref-type="bibr" rid="ref20">20</xref>
        ]. During this searched reading strategy students browse
several paragraphs quickly and select a small number of elements
in those paragraphs to answer the question. On the other hand,
‘high-level’ questions that comprise multiple concepts and require
students to integrate multiple elements of the text are referred to
as “review-and-integrate” [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ]. These questions elicit a targeted
reading strategy, in which students search the text to read larger
text parts intensively to process information relevant to the task.
Whereas more elaborate tasks, such as making a summary, require
students to fully read the text and therefore elicits an intensive
reading strategy. In these elaborate tasks, students infer the task
solution from the text as a whole.
      </p>
      <p>In order to push the conceptual understanding of reading as an
adaptive problem solving process, it is important to understand
how students’ reading actions evolve into reading strategies. This
supports conceptual clarity among researchers engaging in process
analysis and deepens the scientific debate around reading as an
adaptive problem solving process. Furthermore, it can be used to
unravel characteristics of the reading processes and how these
interrelate with student, task and context characteristics.
1.2</p>
    </sec>
    <sec id="sec-4">
      <title>The Present Study</title>
      <p>In this study, an event-based approach is taken to detect students’
reading strategy based on the pattern of reading actions. We use
a method inspired by Read&amp;Answer in which students need to
unmask (i.e. deblur) individual sentences during reading in order to
read the text. This allows us to identify students’ reading actions,
such as sentences opened, read, time spent on relevant sentences,
checking, rereading and task monitoring actions. These reading
actions are visualized to understand how reading actions are
informative of students’ reading strategies use. When students read
intensively, we expect they will deblur every sentence linearly and
open sentence long enough to read the sentence. In case of a search
reading strategy, sentences are opened only shortly to identify the
information and whether this is relevant for the current task.
Finally, in a target reading strategy the student looks for the relevant
section of the text which is then opened long enough to read.
Accordingly, we aim to create a machine learning classifier to detect
students’ reading strategies from reading actions in the trace data.</p>
      <p>We followed a two-tiered process to fulfill this aim. We
visualized students’ reading behavior in graphs, and interactively refined
them to support human coding of the three reading strategies (i.e.
searched, targeted and intensive). In the process additional reading
actions (i.e. checking, re-reading, tab switched to task and stopped
reading after relevant sentence) were derived, to see how they are
related to one of the three reading strategies. Next, all graphs were
classified by humans and used as a supervisory signal to train the
machine learning classifier. Thus, we aim to address two research
questions: 1) Can we (automatically) detect students reading
strategies from the pattern of reading behavior over time? and 2) How
do reading actions relate to students’ reading strategies?
2
2.1</p>
    </sec>
    <sec id="sec-5">
      <title>METHOD</title>
    </sec>
    <sec id="sec-6">
      <title>Participants</title>
      <p>In this study, 44 fourth-year vocational secondary training
students (20 female; 24 male) participated and collected data are part
of a design study into the efects of reciprocal peer tutoring on
task-oriented reading. Students had an average age of 15.56 years
(SD=0.65), and gave active consent after parental consent was given.
Students participated in task-oriented reading during three
economics classes.
2.2</p>
    </sec>
    <sec id="sec-7">
      <title>Measurements</title>
      <p>Each student completed three task-oriented reading sessions at
fourweek intervals. All sessions were similar in set-up, with the only
diference being an added example task in the first session. Each
session consisted of 9 text-task pairs appropriate for vocational
secondary students.
2.3</p>
    </sec>
    <sec id="sec-8">
      <title>Text</title>
      <p>The texts were all informative texts with an average length of 21
sentences per text, and a range of 208 to 516 words. Each text had
three paragraphs discussing environmental sustainability topics,
at a complexity and dificulty level evaluated by two experts on
vocational secondary education.
2.4</p>
    </sec>
    <sec id="sec-9">
      <title>Task</title>
      <p>
        Tasks were developed as text-based, bridging or elaboration tasks
[
        <xref ref-type="bibr" rid="ref18">18</xref>
        ]. This categorization was based on two scales namely the
number of relevant sentences needed to execute the task and the
required level of inferencing between these elements [
        <xref ref-type="bibr" rid="ref12 ref22 ref25">12, 22, 25</xref>
        ].
In text-based tasks, answers can be found within one sentence,
bridging tasks require making inferences about relations between
two or more sentences, and elaboration tasks require a great deal
of inferencing across the text and sometimes making connections
with students’ own prior knowledge [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ]. These diferent task types
are commonly found in reading comprehension measurement
instruments, such as PISA [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] and NT2 [
        <xref ref-type="bibr" rid="ref22 ref25">22, 25</xref>
        ]. Executing reading
tasks implies a process of categorization that involves
identifying the type of task and relevant information sources in a text
[
        <xref ref-type="bibr" rid="ref11 ref16 ref22 ref26 ref5 ref8">5, 8, 11, 16, 22, 26</xref>
        ]. The instruments all consisted of 3 text-based,
3 bridging and 3 elaboration tasks.
2.5
      </p>
    </sec>
    <sec id="sec-10">
      <title>Procedure per session</title>
      <p>At the beginning of each session the students were given ten
statements which they had to answer as being correct or incorrect. The
statements were masked and before answering students had to
tap on the sentence to make them visible. These taps were
timestamped to estimate a reading calibration time per student. Next,
in the first session students were given an example text and task
to familiarize and practice the procedure. Entering the full task,
students are given the first out of nine tasks. Students first saw the
planning page, where they answered questions about the task (e.g.,
dificulty, level of inference, strategy decision and number of
relevant sentences). During the planning phase students could move
freely between the text and the task, upon answering the questions
on the planning page. Students were able to see the complete task,
but apart from the headers, the text was masked and could not
be deblurred. After answering the planning questions, students
would enter the execution phase. During this phase students were
transferred to the text but could, at any time, switch to the task
tab. After task completion, students saw the reflection page asking
which reading strategy they used and which would have been best
for the task. The planning, execution and reflection cycle would
start again for the following eight tasks and texts of the test.
2.6</p>
    </sec>
    <sec id="sec-11">
      <title>Graphs</title>
      <p>The visualizations showed the index of the sentence opened in the
text on the y-axis and time spent on task-oriented reading on the
x-axis. An example graph is shown in Figure 1. Since data was
collected in a classroom setting we used masking to gain information
about students reading process. To read the masked text, students
had to tap on a sentence. Hence providing information about the
order in which sentences were opened, the relevance of the sentence
opened to complete the task and the time a sentence was opened.
The estimated calibration time gained from the ten statements at
the beginning of each test, provided information about whether
a sentence was opened long enough to read. In addition, the time
spend on text and task was logged. The time spend on text and task,
the average calibration time, order of sentences opened, relevancy
of sentences and reading time was then used to visualize students
reading process in graphs.</p>
      <p>Each deblurred sentence was visualized either as a triangle,
indicating that the opening time of the sentence was too short to read
the sentence or as a circle when opened long enough to read (based
on the estimated calibration time). The size of the plot character
indicated the deblurring time of the sentences, with larger plot
characters representing a longer opening time. Blue and red plot
characters were used to indicate sentences with relevant and
irrelevant information for the task, respectively. Vertical lines indicated
a switch from the text to the task.</p>
    </sec>
    <sec id="sec-12">
      <title>Human Classification</title>
      <p>Based on visualizations of students reading behavior, human coders
classified students’ reading strategies as searched, targeted, or
intensive, as described below. A total of 1091 graphs were classified.
The graphed features used to code these reading strategies were
opening time of sentences (e.g. triangle/circle), relevance of
sentence opened (e.g. blue/red), and the number and order of sentences
opened.</p>
      <p>In a searched reading strategy, students browse several
paragraphs quickly and select a small number of elements in those
paragraphs to answer the question. Thus, sentences might be opened
linearly or haphazardly, but most sentences are not opened long
enough to read (i.e. triangle). When students find a relevant
sentence (blue), it should be opened long enough to read (circles).
During searched reading this usually applies for only a few
sentences.</p>
      <p>In a targeted reading strategy, students search for keywords and
then read larger sections intensively to gather task-relevant
information. Reading often starts from the second or third paragraph,
which is then read intensively. This is seen as a cluster of relevant
and irrelevant sentences opened long enough to read (i.e. circle).
Students may instead quickly go through each sentence from the
start of the text before focusing on a cluster of relevant sentences.</p>
      <p>An intensive reading strategy involves reading the text carefully.
This is seen in the graphs as a linear opening of sentences, viewed
long enough to have been read (i.e. circles). Students may either
read the text completely or stop after the relevant text parts to
complete the task.</p>
      <p>Additionally a number of reading actions were coded based
on the graphs (see Table 1). Seventy-three graphs showed that
students read no sentences, so these were excluded from human
and automatic classification. Ten percent of the graphs were coded
by two coders to establish inter-rater reliability.
2.8</p>
    </sec>
    <sec id="sec-13">
      <title>Automatic Classification</title>
      <p>To determine what behavioral features define a reading style–and
how accurately such classifications can be made–we calculated a
collection of features from the logged behaviors of each participant
reading each text and trained a machine learning classifier to predict
the 1018 human-classified reading strategies of students.
2.9</p>
    </sec>
    <sec id="sec-14">
      <title>Features</title>
      <p>
        Fifteen features were extracted from participants’ recorded reading
behavior on each text, including total number of sentences read,
the number of unique sentences read, the number of re-read
sentences, and the number of times the participant switched tabs while
reading. Also included were the location in the text of the first
and last sentence indices that were read (First Sentence Read and
Last Sentence Read), scaled to [
        <xref ref-type="bibr" rid="ref1">0, 1</xref>
        ]. A linear regression was fit to
each text’s sentence indices and each reader’s tapped indices, and
this model’s slope and R2 were included. The reader’s total time
spent reading the text (Time-on-Task), and the standard deviation
of the time they spent reading each sentence (sd(Reading Time))
were included, as well as their median per-sentence calibration time
(Subject Calibration RT ). Proportion Fast Reading is the proportion
of read sentences that the user spent less time on than the mean
of all subjects’ median calibration times (3210 ms).1 Three features
relating to the text were included: the unique ID of the text, and
both Number/Proportion of Relevant Sentences Read measured the
reader’s taps that were on sentences relevant to the answer.
2.10
      </p>
    </sec>
    <sec id="sec-15">
      <title>Classifier</title>
      <p>A tree-based XGBoost (eXtreme Gradient Boosting) classifier was
built in R to classify reading strategy (searched, targeted, or
intensive) based on the 15 features calculated above for each participant
and text. This algorithm was chosen because it learns simple,
interpretable tree models that when boosted (i.e., combined), ofer
1Using Subject Calibration RT instead of the group average calibration time significantly
reduced the classifier’s accuracy.
excellent fit balanced with good generalization, achieving
state-ofthe-art performance in many domains. The classifier was trained
with the multiclass softprob objective function, evaluated with
multiclass logloss, and limited to a maximum depth of 3. Parameters
were chosen after examination of 10-fold cross-validation results.</p>
      <p>A second, text-naive classifier was constructed using the subset
of 12 features that depended on only reading behavior, and not on
details of the texts. Using these same 12 behavioral features, binary
classifiers were built for each reading action (checking, rereading,
tab-switching, and relevant stopping), using a binary logistic
objective function and with error as the evaluation metric.
The reading strategy classifier achieved an overall accuracy of 0.75
(95% CI = [0.73, 0.78], kappa = 0.59), significantly greater than the
no information rate (0.55; i.e., guessing the most frequent class). A
confusion matrix is shown in Table 2. Table 3 shows performance
statistics of the classifier on each reading strategy. A searched
reading strategy was the easiest to identify, with a balanced accuracy
of 0.84, followed by intensive (0.82) and targeted (0.71).</p>
      <p>The most important features for the classifier were Proportion
Fast Reading (gain = 0.50), Unique Sentences Read (0.11), and sd(Reading
Time) (0.06). First Sentence Read and text ID yielded gains of 0.05,
while Time-on-Task and Linear Model R2 each ofered 0.04. Total
Sentences Read, Number of Tab Switches, and Linear Model Slope
had gains of 0.03, and Subject Calibration RT and Proportion of
Relevant Sentences Read each ofered 0.02. Number of Relevant Sentences
Read gave a gain of .01, while Number of Reread Sentences and Last
Sentence Read yielded gains &lt; .01.</p>
      <p>To determine how well reading strategy might be determined
without specific knowledge of the text, a second classifier was
created using only the 12 features related to readers’ behavior (i.e.,
without text ID, Number/Proportion of Relevant Sentences Read. This
text-naive classifier achieved an overall accuracy of 0.73 (95% CI =
[0.70, 0.76], kappa = 0.55), with balanced accuracies for each style
quite similar to those in the 15-feature classifier (searched = 0.82,
targeted = 0.68, and intensive = 0.81).</p>
      <p>As shown in Figure 2, the most important features for this
textnaive strategy classifier were largely the same as for the classifier
Proportion FasptroRpeFasdting
UniqueunSiequneteSnecnetRseRadead</p>
      <p>First SfiresntItnednecxePrRopead
sd(ReadinRgTTsidme)
Linear MoRdesqlR2</p>
      <p>TtiimmeeO-onnTa-Tskask</p>
      <p>Linear ModeslloSpleope
Subject CsuablijbCraalTtiiomneRT</p>
      <p>Total SteontatleSnecnetRseRadead
NumbernoufmTSawbitcShwTaitbcshes
Number of RnuemreRaedreSaednts</p>
      <p>Last SlaesntItnednecxePrRopead</p>
      <p>0.0 0.1 0.2 0.3 0.4 0.5
Figure 2: Feature importance0.f0or the0t.e2xt-nai0v.e4reading
strategy classifier.
with text-based features. The most important features for the
classifier were Proportion Fast Reading (gain = 0.51), Unique Sentences
Read (0.13), followed by First Sentence Read (0.06) and sd(Reading
Time) (0.06). Linear Model Slope, R2, and Time-on-Task, all yielded
gains of 0.04, while Subject Calibration RT, Total Sentences Read,
and Number of Tab Switches each ofered 0.03. Finally, Number of
Re-read Sentences and Last Sentence Read ofered gains of .01.
3.2</p>
    </sec>
    <sec id="sec-16">
      <title>Reading Action Classifiers</title>
      <p>The checking classifier achieved a test accuracy of 0.9, relying
mostly on numRelevantRead (gain=.18) and numReread (.09). The
rereading classifier achieved a test accuracy of 0.77, relying on Rsq
(gain=.49), numReread (.14) and timeOnTask (.09). The tab-switching
classifier reached a test accuracy of 0.83, with important features
being numSwitchTabs (.43) and Rsq (.25). The relevant stop
classifier had a test accuracy of 0.73, relying on numSwitchTabs (.26),
propRelevant (.20), uniqueSentRead (.12), and lastIndexProp (.11).</p>
      <p>Using the human-classified reading actions as additional features
alongside the original 12 calculated behavioral features, we trained
a final classifier to see if these actions contribute to the reading
strategy decision. With an overall accuracy of 0.75 (95% CI = [.72,.77],
kappa = .58), the results were quite similar. Checking, rereading, and
relevant stopping were the three least important features (gains
&lt; .01), and tab-switching was the 11th-most-important feature
(gain = .02). In short, the four hand-coded reading actions yielded
little benefit beyond the 12 automatically-extracted features.
4</p>
    </sec>
    <sec id="sec-17">
      <title>DISCUSSION</title>
      <p>The automated classifier achieved reasonably high accuracy on
the two more common reading strategies, searched and intensive,
while targeted reading presented some dificulty. Despite using
diferent features of reading behavior than the automated
classiifer, human coders were also easily able to recognize searched and
intensive reading strategies. However, targeted reading strategies
also proved dificult to identify for human coders. The features
that were most important to the human coders were the linear or
non-linear opening of sentences, duration of opened sentence (too
fast to read or opened long enough to read), the starting point of
reading and whether sentences provided relevant information to
students to solve the task. While the automated classifiers relied on
the proportion of read sentences that were viewed too quickly
(Proportion of Fast Reading), the number of unique sentences that were
read, the index of the first sentence read in the text, the variance of
the per-sentence reading time, and the R2 of the linear regression
(sentence index read vs. time). Using only these top five behavioral
measures as features already yields a classifier with an accuracy of
0.73. At least three of these features are not used by nor easily
discernable to human raters: the variance of the per-sentence reading
time, the number of unique sentences read, and Proportion of Fast
Reading are all dificult to visually estimate with much precision.
This suggests that reading strategies such as searched, targeted
and intensive reading can be measured automatically, and perhaps
more accurately than by human coding, since the classifier can use
more features of greater complexity to determine a reading
strategy. However, both human coders and the classifier had dificulty
identifying targeted reading, suggesting a need for further research.</p>
      <p>Surprisingly reading actions, such as checking, rereading, tabs
switched and relevant stop (see Table 1), did not help to classify
the reading strategies. Rather, the automated classifier was able to
classify the reading actions separately from the reading strategies.
Thus it appears that even though these actions appear during
reading, they are not necessarily representative of particular reading
strategies.</p>
      <p>Importantly, the classifier did not perform much better with
the addition of either the features requiring specific knowledge of
the text (e.g., the text ID or which sentences are read) nor with
the addition of human-coded reading actions. Thus, we suggest it
would be fruitful for researchers to first use a classifier trained on
automatically extracted behavior-based features. These machine
classifications can then be inspected by human raters, and corrected
if need be. Such human-in-the-loop classification can yield lower
error rates than machine- or human-only systems. Future work
should investigate whether defining more complex behavioral
features can further improve classification, especially for the dificult
and relatively rare targeted reading strategy. Moreover, the relation
between task performance, reading actions and strategies will be
explored to assess the eficacy and eficiency of diferent
strategies for task-oriented reading. This work will inform development
of an intervention to support students’ reading strategies during
task-oriented reading.</p>
    </sec>
    <sec id="sec-18">
      <title>ACKNOWLEDGMENTS</title>
      <p>Thanks to NVIDIA for a grant of GPU hardware to G. Kachergis.</p>
    </sec>
  </body>
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