Extensions for Tobii

extensions for tobiiE-Prime® Extensions for Tobii combines the power of E-Prime with easy to use Tobii eye trackers. The E-Prime® Extensions for Tobii includes the script necessary to integrate E-Prime with Tobii eye tracking technology. E-Studio’s graphical design interface allows users to drag and drop eye tracking functionality into existing E-Prime® experiments or to easily create new E-Prime® eye tracking experiments.

Supports multiple types of studies: Diagnostic and Interactive

  • Face perception and recognition
  • Infant studies
  • Reading (sliding window)
  • Attention patterns and behavior
  • Visual search
  • Scene recognition
  • No head restraint necessary
  • Seamless E-Prime® integration


  • Library of sample paradigms: used for learning and paradigm adaptation
  • Support: E-Prime® support and Tobii hardware support


  • Train subjects to fixate and control eye movements
  • Give feedback on vigilance or attentive behaviors
  • Combine eye gaze data with E-Prime® condition data for powerful analysis
  • Create interactive or passive eye tracking paradigms
  • Create paradigms which change based on subject eye gaze data, AOI hit tests, fixation, and user interaction
  • Allows for the use of Tobii Eye Tracker as a straightforward input device for E-Prime®
  • Supports multiple AOI’s (Areas of Interest). Regions are defined dynamically as stimuli are drawn to the screen
  • Supports dynamic definitions of fixation and dwell time
  • Enable your current paradigms to use eye tracking to corroborate subject compliance, fixation, and cognitive strategies
  • Enable your paradigm to show feedback for training purposes
  • Start and stop trials contingent on eye gaze, fixation, or eye movement criterion
  • Tobii Eye Tracker support added directly to the E-Studio experiment design environment
  • Code library to allow additional run time processing of data
  • Calibrate inside or outside of E-Prime®
  • Three types of calibration inside of E-Prime (regular, manual, infant)
  • Import stimulus images generated by your paradigm, to use with other eye tracking analysis software (including Tobii Studio)
  • Allows the overlay of eye gaze data with your E-Prime® stimuli
  • Stop and start eye tracker to collect data selectively
  • Include validity data for eye tracking quality, to allow the filtering of data
  • Filter subject data based on eye gaze, fixation, and eye movement criterion
  • Three modes of timing synchronization (none, local, and server)


Where may I install my license of E-Prime Extensions for Tobii?
You may install the extensions on multiple machines in your lab if necessary, but only for experiment development. The license agreement allows you to use E-Prime Extensions for Tobii 2.0 for data collection on one machine at a time.

Does E-Prime give support for fixation analysis online?
Yes, follow the link  to the PST Product Service and Support website.  If you have an existing PST Web Support account, use your email address and password to log in.  If you have forgotten your password, you can click the Forgot Password link to have it emailed to you.  If you do not have an existing Web Support account, click the New User link to create a new account.  All you need is your valid E-Prime serial number to register.

Is it possible to use one computer for Tobii and E-Prime Extensions for Tobii?
Yes, if you are not doing video capture you can use one computer. However, you cannot leave the Tobii Studio program open while running E-Prime without interfering with the timing of the experiment.  For optimum performance, we recommend that E-Prime and E-Prime Extensions for Tobii be run on a different computer than Tobii Studio.

Does E-Prime Extensions for Tobii register pupil sizes?
Yes, in the eye gaze data file, E-Prime records the pupil size in millimeters provided by the Tobii Hardware.

Is it possible to create an analogic scale (grading from 1-100) in E-Prime and use in Tobii Studio?
Yes. This requires a very detailed response and feel you can be better served by support. For further information regarding this please contact info@pstnet.com

How could I get information about the analog score in E-Prime? I had problems defining this, is there any place in the script from E-Prime/Studio?
This question requires some interaction. You may want to send your experiment to support as well as some data.

In relation to the Tobii Studio gaze Opacity, how could we control the peripheral vision? Someone could see a part of the image without the Tobii fixation point?
You can’t really control a participant’s peripheral vision. The eye tracker calculates gaze data, where the eye is pointed, which is part of their foveal cision, at the sampling rate of the particular eye tracker model. Peripheral vision would not be captured since the eyes are not aimed at those specific areas of the stimuli. All of the gaze points are captured, and you can adjust the fixation filter settings in Tobii Studio if you want to adjust the duration and size of the area containing the gaze points that make up a fixation.

Can we use the synchronization of E-Prime and Tobii to engage other equipment, like EEG?
The only timing synchronization that we guarantee is the latency correction and independent clock drift connection between Tobii and E-Prime Extensions for Tobii. Depending on the length and type of EEG experiment you are doing, you will want to consider the implications to your analysis. We don’t address timing drift at this time with any other EEG system besides Net Station by EGI. You will need to test the synchronization yourself to see if it is adequate for your situation.

When used in combination with EEG or fMRI, which clock is used?
The synchronization feature that has been added to the gold version of the E-Prime Extensions for Tobii is meant to eliminate drift and the eye tracker latency documented for the Tobii eye trackers between the eye tracker and E-Prime. We have not tested it with auxillary devices.

What is the shape of an AOI?
The AOI in Tobii Studio can be drawn around any object on the slide or video. In E-Prime you will need the coordinates of the object and for irregular shaped objects you will have to draw them. It can be a bit complicated and we suggest you contact support if you need help doing this.

Is calibration in E-Prime done within an experiment (for each subject) or does it have to be done separately?
Subject calibration can be done in E-Prime. The calibration feature included in the E-Prime Extensions for Tobii allows you to calibrate a participant from within E-Prime before the start of an experiment. This eliminates the need to calibrate in Tobii Studio and then switch to E-Prime to run the experiment.

Can we work on the Tobii Studio data on the computer with E-Prime and E-Prime Extensions for Tobii? Or do we need to have access to the computer with Tobii Studio to work on our data?
If you want the E-Prime and Tobii Studio data, you would need to use the E-Prime computer which produces the edat file and eye gaze data file.

Can the E-Prime Extensions for Tobii be used with the Tobii 1750?
Yes, E-Prime Extensions for Tobii is compatible with the 1750 eye tracker.

Is it possible to watch the eye-tracking of the participant in real time? Is another monitor needed? How would it work?
Yes, it is possible to watch the eye-tracking of the participant in real time using the Local Live Viewer feature within Tobii Studio. You would not need a separate computer, but you would need a separate monitor to view the Live Viewer. For more information, see the Tobii Studio Manual.

Can you use the calibration package call in the middle of the experiment?
Yes, you are able to use the calibration PackageCall wherever you would  like in the experiment.

Can we keep the accuracy of calibration if I use the calibration within E-Prime? If I can, where should I see after an experimental session?
No, the calibration accuracy is not saved.

Is it possible to define AOIs which are not square form?
Yes, the AOI in Tobii Studio can be drawn around any object on the slide or video. In E-Prime you will need the coordinates of the object and for irregular shaped objects you will have to draw them. It can be a bit complicated and we suggest you contact support if you need help doing this.

With the old version of E-Prime Extensions for Tobii, the timing of each gaze sample was fairly bad in terms of RTtime of E-Prime when the Eye Tracker lost the eye ball position (validation code says 4). This happened with T series. Is this issue resolved? If so, what should I do? Set the mode of synchronization to a certain one can solve this problem?
The local synchronization corrects this problem.

I am wondering if I need Tobii Studio with the new Gold interface release at all? Is it possible to calibrate the eye tracker solely using E-Prime?
Yes, Tobii Studio is the only interface you have to the TETServer (which now sits in the eye tracker monitor) and it is the only way to troubleshoot the eye tracker. If you are having connection problems between the Tobii eye tracker monitor and TETServer, Tobii Studio provides the only interface to resolve them. Tobii Studio also provides you with many easy to use, useful analysis tools.

I conduct reaction time studies, where participants respond within 1s. How accurate is Tobii in capturing gaze with a 100ms to 1s time frame?
The Tobii eye tracker sampling rate will affect this. For 60Hz, you will get a gaze sample every 16.67ms, for 120Hz every 8.3ms, and for the TX300 you get a gaze sample every 3.3ms. The gaze data samples are time stamped very accurately by the internal TETServer inside the eye tracker hardware. When retrieving the gaze samples in real time, it is important to be aware of the maximum latency for getting the samples in a T60 or T120 is 33ms and for the TX300 is less than 10ms.

What is the default synchronization setting in past versions of E-Prime Extensions for Tobii?
The past versions of the E-Prime Extensions for Tobii did not have synchronization. The equivalent setting in the current release is None.