Millisecond Forums

Could you please provide the link to the experiment's launch page?

http://research.millisecond.com/mitjaback/MentalVisualizationFollowUp.web

Thank you!

Thanks for the link. I can observe the black artifacts in *both* Inquisit Lab and Web 4.0.7.0. (I assume you have an older Lab version installed on your machine -- the artifacts aren't there or are at least less noticeable in 4.0.6.0). Unfortunately I can see no immediate way to get rid of those artifacts. They stem from changes in the code underlying how Inquisit handles GIF animations introduced between 4.0.6.0 and 4.0.7.0, AFAICT.

One option would be to convert the GIFs to some other video format -- that should avoid the "black rectangle" issue, but may involve other drawbacks (increased file sizes; codec issues).

I tried to run Cyberball again with mp4 instead of animated GIFs. Unfotunately, I've got the following error message: Unable to the load media file (...) Verify the file is of a supported video format.
Based on previous posts I thought inquisit could handle mp4 (e.g., http://www.millisecond.com/forums/Topic5921.aspx). Is that wrong?
Is there another video format I can use and which is supported by both Windows and Mac? (mp2 does for some reason not work on my computer. )

Thanks!

Inquisit will work with mp4 *provided that the system in question has a suitable codec available*. As for ensuring cross-platform compatibility, there are basically two options:

(1) Use MPEG-2 encoded videos; they should work equally well under OSX and Windows out of the box.
(2) Use different video formats depending on the platform (e.g. WMV for Windows machines, MOV for Macs). You can achieve this via conditional <include> elements in your script.

You will find both options detailed in the language reference for the <video> element. The documentation for the <include> element also provides a relevant example. Also see: https://www.millisecond.com/forums/Topic9930.aspx

Unfortunately, using mpeg videos does not solve the problem with the "black rectangles" showing up between the single videos. My new idea is to incorporate Cyberball from an external web server into my inquisit script. I would like to start with a general instruction page in inquisit, afterwards redirect the study to this Cyberball version (at some webpage) and finally to conitnue in inquisit with the rest of the study. Yet, I have no clue how to do that. Is actually possible at all?

Yes, that's possible. Set up and register a <batch> script as your active web script:

<batch>
/ file = "introduction.iqx"
/ subjects = (1 of 2)
/ groupassignment = groupnumber
</batch>

<batch>
/ file = "restofstudy.iqx"
/ subjects = (2 of 2)
/ groupassignment = groupnumber
</batch>

Pass the groupid (and preferrably a unique subjectid, too)  -- which determines which "part" to run -- in via a URL query parameter and set the web experiment up to redirect to the webpage hosting your cyberball procedure (both of those things are configured via the Web Script Wizard).
Start the experiment via a link along the lines of

http://research.millisecond.com/yourusername/batchscript.web?part=1

This will run the "introduction" script. Once that's over, you'll be redirected to the cyberball site. From there, redirect back to

http://research.millisecond.com/yourusername/batchscript.web?part=2

which will run the second script. Have the second script override the redirection configured via the Web Script Wizard by setting the defaults.finishpage property to the standard finish page.

Also see the "How to Interoperate Inquisit Web with Online Survey Packages" topic in the documentation for information on passing information between Inquisit Web and other sites / web applications via query parameters.

However, since your 1st script only seems to be a general introduction / study description, it might be easier to realize that part as a generic web page hosted somewhere else instead of using an Inquisit script. I.e., the flow would be

Intro web page -> cyberball site -> Inquisit Web launch page

which would simplify / avoid some of the redirection stuff.

I am having the same original problem of the black rectangles between trials. I also tried different video formats with no success. Is anyone aware of a solution that does not require accessing a different version of Cyberball from an external server?

BTW, I have just re-tested using Inquisit 4.0.8.0 (the current release) and I'm not seeing the black-out between trials. Have you tried that version yet or are you still on 4.0.7.0? Thanks!