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InterestAreas2.Rmd
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---
title: "Interest Areas for Data Analysis"
author: "Jenna Duclos"
date: "October 25, 2016"
output: rmarkdown::html_vignette
vignette: >
%\VignetteIndexEntry{Interest Areas}
%\VignetteEngine{knitr::rmarkdown}
%\VignetteEncoding{UTF-8}
---
## Applying Interest Areas in DataViewer
After `*.ias` files have been created they can be loaded into
DataViewer with EyeLink data files (.edf) to help analyze data and
generate interest area reports. For each trial in an .edf there should
also be one `*.ias`. If you will be working with multiple trials in
an .edf, it is recommended that when you are creating your interest
area files in R you save them with a name that can be easily
identified and related to corresponding trials in `*.edf` files in
DataViewer. As seen in our examples above, the interest area template
for trial 1 was saved as trial1.ias. A cohesive naming scheme across
the .edf trial names and interest area templates will simplify the
matching process. Also, if you have multiple subjects and will be
viewing many .edf files in DataViewer at once, each .edf loaded in a
single viewing session must have a different name even if the content
of the .edf is different.
### I. Interest Areas for Single .edf Files:
1. **Load the .edf in SRR EyeLink DataViewer:**
a) Load EyeLink DataViewer and click File > Import Data... > EyeLink
Data File...
b) Navigate to the directory containing the .edf, select the .edf, and
click Load. The .edf will be loaded in DataViewer in the Inspector
Data window.
2. **Import the corresponding interest area files for the trials:**
a) Click File > Import Data... > Interest Area Template...
b) Navigate to directory containing `*.ias` files, choose all the
`*.ias` files that correspond to the trials in the .edf and and
press Load. The `*.ias` files will be loaded in the Inspector
Data window in the Interest Area Templates subfolder.
3. **Match the correct `*.ias` to the trials:**
a) In the Inspector Data window view all of the trials by
expanding the .edf file by pressing +. Then click on the first
trial and look at the fields that become available below.
b) The field labeled Interest Area Set should have a value of
Empty Interest Area Set. Select this value and when the drop
down menu appears you will see all the `*.ias`. Select the
`*.ias` that corresponds to the trial you are editing.
c) Repeat steps 1 & 2 until each trial in the .edf has an `*.ias`.
The interest areas should now overlay the eyemovement data in the
Trial View window.
Note: If eye movement data is binocular, before creating Interest
Area Reports, toggle between the left and right eye data by
selecting Edit > Preferences > General > and checking/unchecking
Use Right Eye if Binocular. This will help you are select the eye
with the best data across all trials. You can use the EYE_USED
variable on your interest area report to specify which eye is used
for this subject's data.
### II. Interest Areas for Multiple .edf Files
1. **Load multiple .edfs in DataViewer:**
a) Load EyeLink DataViewer and click File > Import Data... >
Multiple EyeLink Data Files...
b) In Import EyeLink Data File window check the Include
Sub-directories box and navigate to the directory containing all
.edfs you want to import, then click open.
c) When the .edfs load check the boxes for the files you want to
import and select Import. All files will be loaded in the
Inspector Data window and sorted by .edf name.
2. **Import the corresponding interest area files for the trials:**
a) Click File > Import Data... > Interest Area Template...
b) Navigate to directory containing `*.ias` files, choose all the
`*.ias` files that correspond to the trials in the .edf and and
press Load. The `*.ias` files will be loaded in the Inspector Data
window in the Interest Area Templates subfolder.
3. **Regroup the Inspector window by trial:**
a) Click Edit > Trial Grouping...
b) In the Available Variables window select your trial label
variable (ex. 'Trial_number') and press >> to move it to the
Selected Variables window and then select Regroup. The Inspector
Data window will now be grouped by the trials instead of .edf file
names. This means like trials for each .edf will be filed
together.
Note: Regrouping the .edfs by trial is not mandatory, however if
.edfs are not grouped by trial, every trial for every .edf loaded
will have to have the .ias paired separately. With multiple .edfs
and trials this can be very time consuming and tedious.
4. **Match the correct `*.ias` to the trials:**
a) In the Inspector Data window select a trial number and look at
the fields that become available below.
b) The field labeled Default Interest Area Set should have a value
of Empty Interest Area Set. Select this value and when the drop
down menu appears select the .ias that corresponds to the trial
you are editing.
c) Repeat steps 1 & 2 until each group of trials has an `*.ias`.
Note: If the .edf has not been sorted by trial, refer to the
instructions for matching the correct `*.ias` to the trials for a
single .edf file.
## Creating Interest Area Reports
Once the interest areas have been specified, DataViewer can be used to
generate interest area reports to provide information on various gaze
measures for each area. Interest area reports can provide information
on fixation count, summed fixation duration, regressions into an
interest area, etc. Many variables are available to generate the
interest area reports and sets of variables can be exported and
imported for easier selection. This is a helpful tool if you will be
creating reports with the same variables for many different subjects
across many different viewing sessions.
1. **Creating Interest Area Reports:**
a) Click Analysis > Reports > Interest Area Report...
b) In the Available Variables window select the variables you
would like in your report and press >>
Note: Reference the SRR DataViewer Manual for a complete
description of each Interest Area Report Variable.
c) When all the variables you want are in the Selected Variables
window click Next.
d) Navigate to the folder you want to save your Interest Area
Report, name the file, and click Save.
e) When Save Viewing Session Changes window appears click OK to
save the changes made (the Interest Area Report will not save if
you do not select OK).
2. **Exporting Interest Area Report Variables:**
a) Click Analysis > Reports > Interest Area Report....
b) In the Available Variables window select the variables you
would like in your report and press >>.
c) When all the variables you want are in the Selected Variables
window click the Export Variable Selection icon below the Selected
Variable window.
d) Click Yes when asked Do you want to save the selection list?
e) Navigate to a folder, name your report variables, and click
Save.
3. **Importing Interest Area Report Variables:**
a) Click Analysis > Reports > Interest Area Report....
b) Click the Import Variable Selection icon below the Selected
Variable window.
c) Navigate to the folder that contains the interest area report
variables that were previously exported (see **Exporting Interest
Area Report Variables**), select the file, click Open.
d) Proceed with saving the Interest Area Report.
## Interest Periods for Data Analysis
For some eye tracking experiments the recording sequences may include
more eye movement data than you are actually want to include in the
interest area report. **Interest Periods** can be created to modify
the portion of data used in a report.
Example: An experiment requires a subject to read a story orally and
then answer a comprehension question. The recording sequence includes
the reading of the story and the question, but in Data Viewer we are
only interested in viewing the oral reading portion. We can use
message events to create Interest Periods that will include only eye
movements that occurred during the oral reading portion of the trial
(excluding those collected during the comprehension question).
1. **Identify Message Events for an Interest Period:**
a) Load the .edf into a new DataViewer session and expand the
expanding the .edf file by pressing +.
b) Select a trial and then click Toggle Message Event Visibility
in the tool bar. In the Inspector window, Message items should be
included with the Fixation items.
c) Identify the message that corresponds to the start of the eye
movement data you are interested in viewing.
Example: For the experiment above we are looking for the message
labeled DISPLAY\_Story because this message indicates when the
story was displayed and the subject began reading.
d) Identify the message that corresponds to the end of the eye
movement data you are interested in viewing.
Example: For the experiment above we are looking for the message
labeled KEYBOARD_End because this message indicates when the
experimenter ended the display of the story because the subject
finished reading.
2. **Creating the Interest Period:**
a) Click Full Trial Period > Edit > New Interest Period.
b) In the Label field enter the name for your interest period
(ex. Target Story, Target sentence, etc.) and change the End Event
Type field from Button Event to Message Event.
c) Click the Details tab and fill in the Value field with the
message that starts your interest period (ex. DISPLAY\_Story).
d) Fill in the End Time Message Text field with the message that
ends your interest period (ex. KEYBOARD_End). Press OK and your
new Interest Period will appear in the Interest Period Manager
window.
e) Select your new interest period and press OK. All fixations
that occurred outside the message events entered will be removed.
Note: You can switch back to viewing all the eye movement by
switching back to the Full Trial Period in the drop down
menu. Interest Periods, much like Interest Area report variables,
can be exported for future use. This will be helpful if you will
be using the same interest periods for many subjects.