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# randomization loop

Hi @sebastiaan ,

Thank you for your previous answers.

In my experimental design, I have 5 picture sets which include 8 pictures. These 5 sets should come random but the 8 pictures should come sequential. I am trying to do this by adding loops one after another. The place where the 8 pictures will be presented on the screen is important so I need to take into account this.

Adding loops one after another is not a good solution.

I am adding 5 " new sequences" which include the 8 pictures. By this way the problem of where to present the pictures is solved, but picture sets randomization problem not solved.

How can ı solve this problem?

## Comments

• Hi Psychlg,

The attached experiment should give you a starting point to customize your experiment. The setup is straightforward you have two nested loop/sequences. In the outer loop you randomly select the set, in the inner loop you chose the images sequentially. Note, In my example I have used text responses not image response, because I don't have stimuli, but you can apply the same principle to show images.

I think I already mentioned it to you, but again, please do our tutorials. The experiment you describe here, has almost the identical structure as the tutorial experiment.

Good luck,

Eduard

• Hi @eduard

I think I did not explain the paradigm very well. The 8 pictures ,which in picture sets, have different x and y coordinates. Thus, I add 8 new sketchpad because I should add each picture in different place each other. But, in this situation each picture set is shown 8 times.

Thank you for your interest.

• HI @psychlg,

If you present 8 images in a loop using different coordinates, use one sketchpad and insert the coordinates as a variable in your loop. Otherwise, what you're doing is basically programming every trial individually. It is a lot more efficient to use loops.

Good luck!

Fabrice.

• hi @psychlg

Really, you should do the tutorial. Step 6 describes exactly how you define x and y coordinates as variables (the part about draw the gaze cue).

Eduard

• edited May 25

Hi @sebastiaan @eduard I succeed it with your help. Thank you for this.

My experiment design is below;

-main_loop

-main_sequence

-loop1

-loop_1_sequence

new_sketchpad

-loop2

-loop_2_sequence

new_sketchpad

........

Now, I have randomization problem again. The loops (loop1, loop2, loop3...) do not show randomly. I select "random" trip and I write the loop names in the table in "main_loop". But, I cannot randomization. Can you help with this problem?

• Hi @psychlg,

The problem depends on how you implemented this structure exactly. Your main loop should contain a variable that can be used to selective run one of the sub-loop selectively (using the "Run if" property of the objects listed under the main_sequence.

For example, if your main_loop contains 3 rows and a column named "blockid", and you have "b1", "b2", and "b3" as that variable's value for the three rows, you'd then have to set the "Run if" property of your loop1, loop2 and loop3 set to "[blockid]='b1'", "[blockid]='b2'", and "[blockid]='b3'", respectively.

Good luck!

Fabrice.

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