v16 released, brings arbitrarily low ITIs

Hi Everyone,

We have news regarding the QRTEngine, the parser and the website.


We have just released v16 of the QRTEngine, bringing some major enhancements to the methods. Most prominent of which is the arbitrarily low Inter trial interval (ITI) fix. We have managed to off-load the request of the next trial to be done during the current trial, rather than at the end. If the trial is long enough (longer than the average time it takes to request a new trial), this should result in a significant decrease in the lower bound of the ITI. We have found that ITIs of 50 ms are within the realm of possibilities now, the exact value depending on the specs of the respondent’s computer, rather than on the connection speed of the respondent and its geographical location.

This fix removes one of the major limitations to the QRTEngine that we mentioned in the paper and in future versions of the QRTEngine we plan to bring the ITI lower bound down even more. However, the solution is not entirely risk-free. Our solution involves juggling HTML input elements across different pages, so that storage of the current trial is separated from the loading of the next trial. Although this is possible in the current version of Qualtrics, Qualtrics support hasn’t confirmed us yet whether they are continuing to support this feature in future releases.  In order to protect the QRTEngine against this, we have turned off the option by default. In order to turn it on, add the following parameter to the Init question code:

As part of the ITI enhancement, we fixed the ‘fixation flash issue’ (causing the fixation to disappear for a frame or two after a page load, which is on by default) and as a result we also support background colors other than white now. This fixation flash fix works regardless of whether you turn the loadDuringTrial toggle on or off.

For a full list of changes, please look at our changelog!

You can download the latest version of the Engine on our downloads page, or by directly taking it from this page.


We have released the source of our Parser on Github, and it can be found here: QRTEParser. Feel free to clone and if necessary fork the project. As we’re looking to build a new interface in JavaFX 2.0, rather than SWT, only the command line version of the parser is available right now. JavaFX should make it easier to make a GUI that’s actually cross-platform, and would allow us to offer a Linux version of the parser as well. We will post more information about the inner workings of the Parser in a tutorial soon.


We have received a lot of support questions, which has allowed us to fine-tune the guides currently present on the website. Next to that, we have updated our FAQ with several extra items (most importantly, how to unhide standard Qualtrics questions) and are currently working on compiling the most common debugging strategies you will need for successfully building your task in the QRTEngine, which can be found here.

Best regards,

– The QRTE Team

About Erwin Haasnoot

Programmer of the QRTEngine, co-author of the QRTEngine paper, website administrator and really excited about possibilities of online experimentation.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code class="" title="" data-url=""> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong> <pre class="" title="" data-url=""> <span class="" title="" data-url="">