random presentation time _ data columns

gak07
New Member

Posts: 3

random presentation time _ data columns Nov 18, 2020 15:58:22 GMT

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Post by gak07 on Nov 18, 2020 15:58:22 GMT

Seeking for a friend!!

Hello,
so I am new to psytoolkit and I just created an experiment however I am having some trouble with 3 things:
1. I need to present a fixation point for a time that's randomly chosen between 300 and 1600 ms (varying each trial)
2. I need to present a fixation point for a time that's equal to = Reaction time - the first random presentation time - fixed variable
3. my column in the data file do not have variables like some experiment of psytoolkit have, I tried everything in my table coding to have that but it seems impossible. Therefore instead of having like in the "go no go experiment" for each line and column, condition information, I only have numbers that don't seem to correspond to what I want (except for my last 2 columns: RT, Correct)

Thank you for helping out a friend!!

alexandra (AEC)
Very experienced

Posts: 126

random presentation time _ data columns Nov 19, 2020 9:07:45 GMT gak07 likes this

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Post by alexandra (AEC) on Nov 19, 2020 9:07:45 GMT

Hi

1. In order to get a random number assigned to a variable in your experiment you use the "set" function and random in the range of 300 to 1600 (an example for setting a variable to a random number can be found in the syntax explanation here).

set $yourvariable random 300 1600

You can also choose, if you would like to define steps in your range of numbers by adding for example a 2 afterwards, if you only want every second number in your range to be chosen from.

2. In order to set a variable to a number that was found based on a calculation you use the "expression subfunction" of set like this

set $yourvariable expression RT - $yourvariable - $fixedvariable

I have used local variables here (identified by the $) which will work if the first presentation time is at the start of each trial. If you mean the first presentation time of all trials you will need to use a global variable (identified by a &) for your first presentation time in order to save the information across trials.

3. Only information that is written after the function "save" in your task is actually saved. You will need to take a look at what variables you are saving there, which correspond to the numbers you see in your data file. Most times variables contain numbers, which may be why you see only numbers in your data file. If you have character information (defined by using " " around the text) in your table and you call a column using @columnnumber in order to save information from there, for example, you should also see character-based information in your data file.

gak07 New Member Posts: 3	random presentation time _ data columns Nov 20, 2020 9:51:03 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by gak07 on Nov 20, 2020 9:51:03 GMT Thank you so much for your response!!

random presentation time _ data columns

Post by gak07 on Nov 18, 2020 15:58:22 GMT

Post by alexandra (AEC) on Nov 19, 2020 9:07:45 GMT

Post by gak07 on Nov 20, 2020 9:51:03 GMT