RE: How to insert a blank without messing up rest of trial?

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RE: How to insert a blank without messing up rest of trial?

How to insert a blank without messing up rest of trial?

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Anoushka Shahane	Anoushka Shahane posted 10 Years Ago Topic Details Share Topic
Group: Forum Members Posts: 6, Visits: 37	Hello everyone! My task is quite simple: I flash letters on the screen and if there is an A followed by an X, that is a target so subjects click the left mouse button. If it is any other sequence of two letters, it is a non-target, so subjects click the right mouse button. In this particular trial, there is a voice that says "If X Target" when it is A followed by X, and a voice that says "Nontarget" when it is any other sequence (latter half code not shown below). So the sequence should be: blank A blank X blank "If X Target" But it is currently: blank A blank X "If X Target" So the sound is coming when the X is still on the screen. If I go to the stimulusframes in <trial ax_xWAND> (bolded line of code below) and insert a blank after ax_x to try to fix this, the X doesn't even show up and the whole branched trial gets messed up. How do I go about inserting the blank while retaining the X so then the "If X Target" voice shows up when the screen is blank right after the X? Any insight into this matter would be appreciated greatly. Thank you very much! <trial ax_aWAND> / stimulusframes = [1=blank, ax_a] / pretrialpause = 800 / trialduration = 1950 / posttrialpause = 900 / validresponse = (" ", noresponse) / correctresponse = (noresponse) / branch = [trial.ax_xWAND] / ontrialend = [if ( block.ax.totalcount >= 2 && trial.ax_aWAND.correct == false ) values.axtestcomissionerrorcount += 1] / ontrialend = [if ( block.ax.totalcount >= 2 ) values.axtestcomissiontrialcount += 1] / ontrialend = [if ( block.ax.totalcount >= 2 ) values.axtestcomissionerrorrate = values.axtestcomissionerrorcount / values.axtestcomissiontrialcount ] </trial> <trial ax_xWAND> / stimulusframes = [1=blank, ax_x, IfXTarget] / pretrialpause = 100 / trialduration = 1250 / posttrialpause = 800 / inputdevice = mouse / correctresponse = (lbuttondown) / ontrialend = [if ( block.ax.totalcount >= 2 && trial.ax_xWAND.correct == false ) values.axtestomissionerrorcount += 1] / ontrialend = [if ( block.ax.totalcount >= 2 ) values.axtestomissiontrialcount += 1] / ontrialend = [if ( block.ax.totalcount >= 2 ) values.axtestomissionerrorrate = values.axtestomissionerrorcount / values.axtestomissiontrialcount ] </trial> Tags blanks CPT sound stimulusframes
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Dave	Dave posted 10 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 104K	/ stimulusframes = [1=blank, ax_x, IfXTarget] means you're presenting blank, ax_x and IfCTarget all in the same, 1st frame, i.e. at the exact same point in time. If you want your sound to be played at a later point, you ought to present it at a later point in time, i.e. something along the lines of / stimulusframes = [1=blank, ax_x; 20=blank, IfXTarget] adjusted to whatever timing you want or need.
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Anoushka Shahane	Anoushka Shahane posted 10 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 6, Visits: 37	Excellent, thank you very much for your assistance. I thought that stimulusframes were just flashed consecutively -- this makes way more sense now. Thank you!
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Dave	Dave posted 10 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 104K	In addition note that /stimulustimes exists as an alternative to /stimulusframes. /stimulustimes allows you to specify the desired presentation timing in milliseconds instead of ordinal frame number: / stimulustimes = [0=a,b,c; 100=d,e; 500=f; ...]
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