Knowledge Base

Synchronization 10 Synchronization

How To Determine The Delay Between The

Observer Xt And Tobii Pro Software

Data synchronization

The system described in this note makes it possible to start recording in Tobii Pro software the moment you start an observation in The Observer XT. The eye tracking data are aligned with the observational data scored manually. However, there may be a delay between the start of the observation and the start of recording in the Tobii Pro software. The delay may be caused, among other things, by delays in the network communication. As a result, there may be a mismatch between eye tracking data and observational data.

To measure the delay

1. Define in your coding scheme a Point event labeled, for example, sync.
2. Start an observation as usual.
3. Ask the test participant to perform an action that could be seen on the screen (for example, typing in a letter in a web field or the Windows Notepad).
4. The very moment he/she performs that action, score the sync event.
5. Import the video made by the Tobii Pro software into The Observer XT, and look when the letter appears on the screen. The difference in timing between that time and the time that you scored sync gives you the value of the delay. This method is less precise than the previous as it relies on the coder's reaction time.

To compensate for a delay

1. Take note of the value you measured with one of the two methods above. Synchronization
2. Open the observation and click the Offset button.
3. Click Numerical offset.
4. Next to the name of the event log containing the eye tracking data, enter this delay. For example, if the delay was 0.5 s, then enter 00:00.500.

For more information, in The Observer XT Help see External Data >

Import External Data > Manual Synchronization.

Source: The Observer XT 17 - Technical Note - Tobii Pro Eye trackers