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How do I both randomize the order in which my trials appear and set the number of "correct" response trials that should appear during my experiment?

psychnewbie — Tue, 23 Jul 2019 11:14:48 GMT

I'm working on a version of a GNAT, and the project's PI wants to be able to specifically set the number of "correct pairs" (or pairs of images that are designated as requiring the press of a space bar) that participants are shown. How can I do this while also randomizing the order in which participants see trials?

RE: How do I both randomize the order in which my trials appear and set the number of "correct" response trials that should appear during my experiment?

Dave — Tue, 23 Jul 2019 11:14:48 GMT

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[b]psychnewbie - 7/23/2019[/b]

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[b]Dave - 7/23/2019[/b]

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[b]psychnewbie - 7/23/2019[/b]

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There isn't sufficient information here to give a response. Ordinarily, you simply create two <trial> elements -- one that displays a "correct pair" and thus requires a response, another one that doesn't -- and then you randomize their order via the <block>'s /trials attribute.

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I've done that, but is there any way to (for example) specify that within a block of 50 trials, the "correct pair" trial appears 30 times? Or is that not compatible with randomizing trials within blocks?

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That's perfectly possible. You simply enter the trials in the desired proportions into the noreplace() selection pool in the <block>'s /trials attribute.

/ trials = [1 - 50 = noreplace(correct_pair, correct_pair, correct_pair, incorrect_pair, incorrect_pair)]

will run exactly 30 instances of <trial correct_pair> and 20 instances of <trial incorrect_pair> in random order, i.e. a 3:2 ratio.

RE: How do I both randomize the order in which my trials appear and set the number of "correct" response trials that should appear during my experiment?

psychnewbie — Tue, 23 Jul 2019 10:04:53 GMT

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[b]Dave - 7/23/2019[/b]

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[b]psychnewbie - 7/23/2019[/b]

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RE: How do I both randomize the order in which my trials appear and set the number of "correct" response trials that should appear during my experiment?

Dave — Tue, 23 Jul 2019 09:54:44 GMT

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[b]psychnewbie - 7/23/2019[/b]

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