Hello. I’m trying to design an odd-ball auditory paradigm but I’m having problems with the randomization and repetition of trials. I think I’m making some mistake with the block editor and macros.
I will use two auditory stimulus: a target stimulus TS ( 20% probability of presentation) and a non target stimulus NTS (80% probability). The subject will press a key just when he/her recognizes the target stimulus. My block has to have 150 trials (80% trials should be NTS and 20% TS). The TS and NTS presentation has to be randomized and I’ll use variable intervals ranging from 500 to 1000 ms. I’ve created two blocks. Block 1 for the trial with NTS event and Block 2 for the trial with TS event. For Block1 I have used the Condition Expresion “number of trials presented in this block is equal to 130 trials” and in MAcros option I have chosen If true option “repeat the block” (without any expression). For block2 I did something similar: Condition Expression “number of trials presentes in this block is equal to 20 trials” and Macros option : If true “repeat the block”. I also selected “randomize trials in the block” (block editor) and in Trial variables (Experiment) I chose ISI duration levels (500,1000) and level selection “Random with no replacement”.
When I run the experiment just the NTS is presented continuosly, without changes in interval stimulus duration.
Is there any Macro expression that allow me to repeat my specific trial a% of times?..(cause when I use the Macros option repeat the current block, don’t let me to choose an specific number of repetitions)I Understand that if my trial has just one event and I choose the option “Number of trial events equal to 130” it doesn’t work because my trial has just one event and what i’m trying to do is repeat the same event x number of times .
Thanks
I would suggest using only one block for this. Using the one block, you will not need to use macros.
Block --------> NTS Trial ----> NTS Event (NTS list of 130 items)
same block ------> TS Trial ------> TS Events (TS List 30 items)
Thanks Monika. I have followed your advice and it works. But I still have some problemes:
- I’m having problems with the randomization of ISIs. I have to use ISIs ranging from 500 to 1000 ms in a randomized way. I have selected in trial variables window the option ISI duration:levels: 500, 1000 ms and in level selection: i have chosen Random with no replacement; but when I run the experiment the interval between trials is always the same: the shortest.
- We will use different series of experiments; some of them last 6 minutes and other 56 minutes…I need to display events (NTS and ST) in a repetitive way (with the same structure : 20% presentation probability TS and 80% presentation probability TS)…so, for example : I selected in expression editor (block editor) Time since Start of Experiment: is equal to: 6000 miliseconds; to obtain a block that lasts 6 minutes repeating the NTS trial ans TS trial…but again, whe I run the experiment it just lasts the time required to present the list of NTS events ans TS events…Can I modify block duration with other option?..
3.When I have to use a block that lasts long periods (eg: 56 min) …Is there any option that allow me to repeat the events in an specific % of times (eg:80% nts AND 20%ts) without to repeat manually the list of NST events and TS events?
Thanks
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There are two areas to check to see if this was implemented correctly. Under the Input tab where it says “Only after a time limit” there is a drop down box which the default is set to Fixed. You have to change this to reflect the ISI you created. Also, within the Trial Variable and the Level Selection tab, under “Randomize levels before the start of” it needs to say “Each Trial.”
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For this question it would be best if I can see your experiment. Can you post your experiment as an Experiment Package? This is found under the File menu within SuperLab.
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SuperLab can repeat a block and control the number of times trials are being repeated but on a count basis, not percentage. If you want to do this it can be done under the Trial Editor’s “When to Present tab.”
How to repeat auditory events
Dear Monika,
I have posted the basic design of the experiment (auditory oddball).
I have followed your advice related with ISIs intervals (Input tab) and repetition of trials (trial editor), but I do not achieve to obtain the repetition of trials that I need or the specific block duration (I have chosen 1 minutefor this example)
thanks
2-luglio.zip (5.66 KB)
Within the Block Editor and the When to Run tab, change the expression “Present the trials in this block” to “While the condition expression is true.”
Also, change the expression from “is equal to” to “is less than.” By having it equal to 60000 ms, it would only work if the expression is evaluated when the elapsed time is exactly 60000 ms, which is a low probability event.