[solved] Help with experiment setup

frankanayet

Hi Sebastiaan,

I have a question about the experiment I am attaching. For some reason, in the number trial sequence. After I make a respond the stimuli presented changes even though I intended to show the same stimuli for the remaining of the [time_left] variable. I had used a similar setup previously and worked fine and that is why I don't understand what I am doing wrong. Would you mind checking it and help me figure out what is wrong?

https://www.dropbox.com/sh/zrorse719nieqsv/4Ku0NxbDye

Thanks for any help,

lvanderlinden

Hi Frank,

If you simply cut-and-past your script in "Prepare_Trial" to the prepare instead of the run phase your problem is solved. This is because the prepare routine of each item in a sequence is called before the run routine.

• A sketchpad canvas is constructed during the prepare phase. Therefore, if you have an inline script that sets a variable in the run phase (i.e., after the prepare phase), it will not be available in the subsequent sketchpads. In your case, this means that the sketchpad "HatchMark" is always using the Task, Number, and Placement values that were meant for the previous trial (that's why the first experimental trial is identical to the practice trials).

• A feedback canvas is constructed during the run phase. Therefore, you will be able to use all variables, regardless of whether they have been set in the prepare or in the run phase. That's why Hatch_Continued is not one trial behind, which causes the discrepancy between the HatchMark and Hatch_Continued.

Finally, if I try to run your experiment it crashes at line 33 of "Prepare_Trial", because a string like "2900.0" cannot be converted to an integer (because of the decimal). I'm not sure why this doesn't cause a crash on your system, but I would recommend to convert the strings to floats, just to make sure it will not crash on other systems either:

self.experiment.set('Jitter', float(Trial['jitter']))

I hope this helps! Please let us know if you have any further questions!

Best,

Lotje