FAQ: How do I extract Reading Measures from Data Viewer?

[Sam]

In reading research it is common to report standard "reading measures" which refer to a critical word or phrase in the text. Common reading measures are defined below.

FIXATION DURATION MEASURES

1. Single Fixation Duration - The duration of a fixation on a target region, provided that region is fixated one time only, and that the one fixation does not occur after fixations on words further along in the text.
   
2. First Fixation Duration - The duration of the first fixation on a target region, provided that the first fixation does not occur after fixations on words further along in the text.
   
3. Gaze Duration - The total duration of all fixations in a target region until the eyes fixate a region of text that is either progressive or regressive to the target region, provided that the first fixation on the target region does not occur after any fixations on words further along in the text.
   • Note: This measure is typically referred to as "Gaze Duration" for one-word regions of text and "First-Pass Duration" for multi-word regions of text. For simplicity in this reading guide, this measure will be referred to as " Gaze Duration" , whether the region is one word in length or more than one word in length.
4. Right-Bounded Duration - The total duration of all fixations in a target region until the eyes fixate a region of text that is progressive to the target region, provided that the first fixation on the target region does not occur after any fixations on words further along in the text.
   • Note: This measure, as well as Regression Path Duration below, is sometimes referred to as Go-Past Duration. These two definitions of Go-Past Duration are distinguished here by calling one Right-Bounded Duration and the other Regression Path Duration.
5. Regression Path Duration - The total duration of all fixations that occur from the first fixation on a target region until the target region is exited in a progressive manner (including fixations on the target region and fixations on words regressive to the target region), provided that the first fixation on the target region does not occur after any fixations on words further along in the text.
   • Note: This measure, as well as Right-Bounded Duration above, is sometimes referred to as Go-Past Duration. These two definitions of Go-Past Duration are distinguished here by calling one Right-Bounded Duration and the other Regression Path Duration.
6. Re-reading Duration - The difference between Regression Path Duration and Gaze Duration.
   
7. Total Duration - The total duration of all fixations in a target region.
   

FIXATION RATIO MEASURES

1. First-Pass Regression Ratio - The proportion of fixations following fixation on the target region that are regressive relative to the target region (and not progressive), provided that words: 1) further along in the text have not yet been fixated (i.e., the region was not skipped during first-pass reading) and that 2) the target region has not already been fixated and exited.
   
2. First-Pass Fixation Ratio - The proportion of times that the target region is fixated before any progressive text is fixated (as opposed to times when the target region is skipped during first-pass reading)
   • Note: First-Pass Fixation Ratio is First-Pass Skipping Ratio.
3. First-Pass Multi-Fixation Ratio - The proportion of times that the target region is fixated more than one consecutive time before any other text that is progressive or regressive to the region is fixated, provided that the target region is fixated at least once before any material progressive to the region is fixated (i.e., provided that the target region is not skipped during first-pass reading).
   

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Extracting Reading Measures from Data Viewer
There are two methods to extract Reading Measures from Data Viewer:

METHOD 1
A flexible approach for reading analysis is to use the Get Reading Measures tool. This allows you to precisely define the critical word or words for your analysis.

You can download the tool and find detailed instructions on how to use it from the support thread linked below.

• Get Reading Measures Application

METHOD 2:
An alternative method for extracting reading measures is to use a Data Viewer Interest Area Report. This method is direct but requires that your target regions (and any non-target regions) are properly defined as Interest Areas before you generate the report.

The advantage to this method as compared to using the Get Reading Measures tool is that the output from Data Viewer will contain the values of these dependent measures directly. he disadvantage of this method is that if you want to generate these dependent measures for regions of text that are not the same as the currently defined Interest Areas (e.g., if you want to get Gaze Durations on a region composed of words 4 to 6 and currently your viewing session has Interest Areas around each work individually) then you will need to redefine your Interest Areas before generating the Interest Area Report.

Redefining Interest Areas (If Necessary)
Redefining IAs can be more time-consuming than using the Get Reading Measures tool. You have two main options:

• Manual Merging: In Data Viewer, select the IAs you want to combine, right-click, and choose Merge.
  
• Re-generate from Experiment Builder: Do a "dummy run" of your experiment with different word segmentation settings (Edit -> Preferences -> Built-In Interest Area Preference -> WORD_SEGMENT) in Experiment Builder to create new Interest Area Set (.ias) files, then apply them to your Data Viewer session.
  

Reading measures can be extracted from a Data Viewer Interest Area Report as follows (you will need to make sure to include the variables listed in the definition of the measure in your Interest Area Report):

• Single Fixation Duration - IA_FIRST_FIXATION_DURATION, if IA_FIXATION_COUNT == 1 and IA_FIRST_FIX_PROGRESSIVE ==1
  
• First Fixation Duration - IA_FIRST_FIXATION_DURATION , if IA_FIRST_FIX_PROGRESSIVE ==1
  
• Gaze Duration (a.k.a. First-Pass Duration) - IA_FIRST_RUN_DWELL_TIME, if IA_FIRST_FIX_PROGRESSIVE == 1
  
• Right-Bounded Duration (a.k.a. Go-Past Duration) - IA_SELECTIVE_REGRESSION_PATH_DURATION, if IA_FIRST_FIX_PROGRESSIVE == 1
  
• Regression Path Duration (a.k.a. Go-Past Duration) - IA_REGRESSION_PATH_DURATION, if IA_FIRST_FIX_PROGRESSIVE==1
  
• Re-reading Duration - [IA_REGRESSION_PATH_DURATION, if IA_FIRST_FIX_PROGRESSIVE == 1] – [IA_FIRST_RUN_DWELL_TIME, if IA_FIRST_FIX_PROGRESSIVE == 1]
  
• Total Duration - IA_DWELL_TIME
  
  
• First-Pass Regression Ratio - check the frequency of IA_REGRESSION_OUT, if IA_FIRST_FIX_PROGRESSIVE==1
  
• First-Pass Fixation Ratio - check the proportion of IA_SKIP and subtract it from 1
  
• First-Pass Multi-Fixation Ratio - check the proportion of IA_FIRST_RUN_FIXATION_COUNT > 1, if IA_FIRST_FIX_PROGRESSIVE ==1
  

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Note: It's important to understand the different ways that the Get Reading Measures tool and the standard Interest Area Report handle fixations that do not fall within any defined Interest Area (IA), such as fixations on the space between words.

"Get Reading Measures" Approach
The Get Reading Measures tool simply ignores any fixation that is not inside a defined IA.

"Interest Area Report" Approach
The Interest Area Report provides several options for handling these outlier fixations. By default, these fixations are simply treated as not being on any target region. You can change this behavior by going to the Edit menu -> Preferences -> Output/Analysis and check the box for "Use Nearest Interest Area for Outlier Fixations". This will force outlier fixations that are not on any Interest Area to be assigned to the Nearest Interest Area

Alternatively, you can delete fixations outside of Interest Areas by right-clicking on your data and use the Clean Function to delete fixations that are outside of any Interest Area.