[CogSci] How present text, audio, or video filesكحنززغ dynamically in Labvaned

Badr ELHAMRI badrelhamriok at gmail.com
Mon May 18 07:44:54 PDT 2020


تتعطانااغ
بتاريخ ١٤‏/٠٥‏/٢٠٢٠ ١٢:٠٥ م، جاء من "Lee Leah" <leah at labvanced.com>:

> In this How-To, I would like to explain how to import and present stimuli
> dynamically using variables and the event system. By using the Labvaned
> <http://www.labvanced.com>Trial System one can easily change the type of
> stimuli (image, text, or video) for each trial. While this is the easiest
> and fastest way to create trials with various stimuli, it sometimes can be
> useful to choose an alternative / programmatic way to select stimuli for a
> given trial/ frame. Here is how you can do this:
>
>
>
> 1-Create a variable with data format “array”, and data type “file” (for
> audio or video data) or “string” or “numeric” for text / numeric stimuli.
> 2-Now click on the folder icon (upload file), for audio or video data you
> can select multiple files, for text or numeric data 1 (CSV) file. The CSV
> file will be parsed and the array will be filled up with the comma
> separated entries.
> 3-After you press ok you should see the array filled up with values as
> shown below:
>
> We have now saved the stimuli inside a variable - so next we need to read
> them out, each trial a new/different. Also we want each subject to see a
> different order/ sequence of the stimuli.  So the next thing we do is:
>
>  4-Create an event (only once in the introductory task ) with trigger
> “onFrameStart” and action “ShuffleArrayEntries” for our stimulus array.
> 5-Then we go to the experimental task and create an event to read out a
> new stimulus for each trial. For this, we create an event with Trigger
> “onFrameStart” and “SelectFromArray” as an action. For “array variable” we
> choose our created stimulus array, for index variable we choose the system
> variable “Trial_Nr,” and as output we define a new scalar variable which
> will hold the single stimulus/file.
>
> 6. Now to show a (different /selected) value for each trial, first set the
> “#Trials” (lower left corner) to how many stimuli you want to show (also
> include some logic to go to the next trial, e.g a fixed frame duration).
> 7. For showing numbers or text include a text element on your frame and
> insert the scalar output variable via the red variable insert
>
> 8. For images, video, or audio data use the action “setObjectProperty”
> “Filedata” to and the scalar file output variable (e.g this will determine
> what image is shown inside the image object):
>
> That’s it. Now you can test/play your study and you should see a new
> value/stimulus for each trial. To test this on your own feel free to use
> and import our sample study:
>
>
>
> Best regards,
>
>
> The Labvanced <http://www.labvanced.com> Team
>
> Leah Lee
>
> leah at labvanced.com
>
> www.labvanced.com
>
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