FAQ: What messages do I need to send to Data Viewer if I'm not using Experiment Builder?

[SR-SUPPORT]

To ensure Data Viewer can correctly parse and display your experiment, your stimulus presentation software should send several key types of integration messages to the EDF file. Our EyeLink Data Viewer Integration Messaging Protocol guide outlines the most important ones. For complete details, please see the Data Viewer User Manual (Help menu -> Contents -> Protocol for EyeLink Data to Viewer Integration).

1. Trial Demarcation Messages (Start/End of Trial)
   Purpose: These messages tell Data Viewer where each trial begins and ends.
   • Start of Trial Syntax: TRIALID [trial_number]
     TRIALID 1
     
   • End of Trial Syntax: TRIAL_RESULT [result_code]
     TRIAL_RESULT 0
     
   Note: If your software uses different messages or TTL pulses to mark trials, you can change the defaults in Data Viewer by going to Preferences > Data Loading before importing your data.
   
      
   
   
2. Image Loading Messages (Stimulus Backgrounds)
   These messages tell Data Viewer which image to display as the background for a given part of the trial and when it appeared.
   Syntax for IMGLOAD message:
   !V IMGLOAD <location type> <image_path> <x> <y> [width] [height]
   Example of an IMAGELOAD message for an image named stim1.png with it's center location at pixel 960x540:
   !V IMGLOAD CENTER images/stim1.png 960 540
   
   
3. Trial Variable Messages (Trial-Level Data)
   Used to send trial-level data (e.g., condition, block, accuracy). These become variables in Data Viewer that you can use for grouping and in reports.
   Trail variable syntax
   !V TRIAL_VAR <variable_name> <value>
   Example message for a variable named "Condition" with the value of "gap":
   !V TRIAL_VAR Condition gap
   
   [Note: These messages should be sent at the end of each trial, just before the TRIAL_RESULT message.
   
   
4. Interest Area Messages (Defining IAs)
   These messages pre-define the shape and location of Interest Areas for your trial.
   • Rectangle IA Syntax:
     !V IAREA RECTANGLE <id> <left> <top> <right> <bottom> [label]
     
   • Ellipse IA Syntax:
     !V IAREA ELLIPSE <id> <left> <top> <right> <bottom> [label]
     
   • Freehand IA Syntax:
     !V IAREA FREEHAND <id> <x1,y1> <x2,y2> ... <xn,yn> [label]
     

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General Event Messages (Crucial for Analysis)
Finally, it is critical to send "standard" messages to mark all key trial events, such as when a stimulus appears or when a response is made. These messages are essential for creating Interest Periods in Data Viewer to limit your analysis to specific time windows.