Eprime with TET

[li Tina]

Hi there,

I have some questions about the E-prime with eyetracking extensions.

(1) Is it possible that a single E-prime file with TET creates two gazedata. files-one for a practical block and one for a testing block?

(2) Can anyone explain the TETWaitForFixation Packgage Call to me? Does it mean that the experiment will only proceed to the next slide after the eyes have fixed on the screen for a certain amount of time? Can I add this package without requiring a mouse or keyboard input?

(3) How is the AOI calculated? I had a fixation stimuli with coordinates within (0.46-0.54, 0.44-0.57). Sometimes the AOI shows nothing when the hit test suggests that both eye gazes are within the fixation stimuli. May I know why? Is it because AOI takes an average of something?

Thank you very much for your help.

Best regards,

Tina

[he...@primepsych.solutions]

Hello Tina,

I would be happy to help. For the sake of clarity, I have numbered my responses to match your questions. 

1) This is definitely possible but requires a bit more InLine script than the original TETFixedPositionAOI sample. In short, you'll basically have to make a duplicate of the SaveGazeData subroutine in the User Script. One copy of this script will be for your Practical block and the other is for your testing block. Then, in your SaveGazeData InLine objects (of which there will need to be two), just make sure you are referencing the correct subroutine in the User Script. 

2) I would be happy to explain the TETWaitForFixation Package call. I've actually done quite a lot of testing on this call when I was at PST. Your assumption of the functions of this call are 100% correct. Its purpose is to basically pause the experiment on a single fixation point  (usually a SlideText sub-object) until the participant looks at it for a pre-defined amount of time or terminated by a keyboard or mouse press to move on. While it's a handy little package call, it has a few things that NEED to be in place in order for it to work as intended. They are as follows:

     a) It can only be used in conjunction with a Slide object (that is named in the first parameter of the Package Call (usually called Fixation)

     b) The Slide sub-object on which participants will be fixating needs to be called Fixation. (this is usually a SlideText sub-object)

     c) The Slide object needs a Duration of 0

     d) The Slide object needs a Keyboard Input Mask with an Allowable set to {ANY}, a Time Limit set to "(until feedback)" and an End Action set to "(none)"

3) The AOIs in E-Prime are actually all calculated in the SaveGazeData InLine object at the end of the procedure (after the trial has already run). Generally, the easiest way for E-Prime to calculate AOIs is by using the strHit method in conjunction with Slide sub-objects. So basically the coordinates of an actually object aren't as important when calculating AOIs, just the object's name. This hit test just looks at where the eyes are on the screen and whether or not they are currently above any Slide sub-objects. I honestly do not know why your AOI shows nothing when the hit test suggests that the gazes are within the fixation or stimuli. The AOI isn't taking an average of anything it's literally just going "is the user looking at this sub-object?". This issue may be because of the script in your SaveGazeData InLine object. That is the first place I would look. 

I hope this is helpful.

Devon Struthers

[li Tina]

Dear Devon,

Thank you so much for your detailed replay. It is extremely helpful for me. May I follow up some questions?

1) After I make a duplicate in the User Script and two SaveGazeData, Eprime records all the data in one file. How do I indicate that I want to have separate files for each block? I have attached my Inline files and the user script. It will be great if you can have a look.

2) With the TETWaitForFixation Package call, if I look at the fixation for the pre-defined time and do not press the keyboard, will the experiment proceed to the next slide? I have tried the sample file given by Tobii. No matter how long I stared at the fixation, the experiment will not continue until I press the keyboard.

Thank you very much for your help.

Best wishes,

Tina

[Dan Rice]

Dear Devon and Tina,

I'm having exactly the same issues that Tina appears to be having with the TETWaitForFixation package call.  I believe that I correctly set all of the parameters that you mention correctly, but I still cannot get the slide to advance through focus alone.  I have to hit a key (possibly only the spacebar, that's the only one I tried).  Is there some other hardware or software requirement or other setting that we also need to address?  I'm on eprime 2.0 pro, and using a Tobii X-2 60.  I also set the duration to a short 500ms.  For what it's worth, I don't get the package call to work with the TETFixedPositionAOI example program either. So I think there must be something else going on; I'm just not sure what.  Any resolution to this would be great, as I think it sounds like a really nice tool.

Cheers,

Dan