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Two overlapping sequences which are created randomly in every test


I’m new to OpenSesame and after building some simple test experiments, I’m trying to create the first “real“ experiment.

While doing the test you see a rectangle, which is divided into four squares. In one of them an “X“ will appear and you have to respond to it with a certain key.  After the respond, the “X“ will appear in another square. I created 8 blocks with a little break between the blocks. This already works fine. I got a list of four pictures. Every picture shows the “X” in one of the squares, so every picture is shown several times randomly throughout each block.

But now, I want the program to define two sequences for the positions of the “X” at the start of the test. These sequences should be overlapping in the first two positions. Something like 1-3-2-4 for the first sequence and 1-3-4-2 for the other sequence. One sequence should be shown in blue squares, the other one in red squares.

I could make a list of eight pictures, four for each color, and sort the sequences by hand. But then every person, who makes this test, would get the same sequences. It would be nice if the program would create the sequences randomly at the beginning of the test and show both of them alternately.

For example, the trials in the first block could look like:

Seq. 1 -> Seq. 1 -> Seq. 2 -> Seq. 1 -> Seq. 2…..

The second block could start with:

Seq. 2 -> Seq. 1 -> Seq. 1 -> Seq. 2 -> Seq. 2......

So, is it possible that the program creates two overlapping sequences at the beginning of the test and is there a way to define that one of the sequences should appear in 80% of all trials and the other sequence in only 20%?

I hope my problem is clear and I’m grateful for all tips and advices.




  • Hi Christian,

    i am not sure about what is your question. If it is possible to create such sequences for every individual at the beginning of the experiment? So the answer is yes! 🤩

    Very likely you will need an inline_script. But this depends on your restrictions of the sequence.

    Here is an example of a sequence i created for one of my experiments. You may adopt it to your needs.



  • Hi Stephan,

    thank you for your reply. Yes, this is what I meant. I wasn't able to create different sequences for every individual at the beginning of the experiment.

    Thanks for your example. I'll try to create something for my experiment based on your code.



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