2-back task, need help!

Hello! I need help and i don't about programming but I need this for our research. My dilemma is that I need it to be only 10 matches and 15 no matches but the program is programmed to give random matches and no matches. Got it from www.psytoolkit.org/experiment-library/touch_nback2.html . How can I set it only to 10 matches? What condition should I put in if-else? Thank you very much!

options

 bitmapdir stimuli

 sounddir stimuli

 set &maxrt 760 # stimulus presentation

 set &iti 2000  # intertrial interval

 set &choosechance 3 # 1 in 4 are matching

 mouse on

 

sounds

 sound_good good.mp3

 sound_bad  wrong.mp3



fonts

 arial 18



bitmaps

 letterA ## 15 letters

 letterB

 letterC

 letterD

 letterE

 letterH

 letterI

 letterK

 letterL

 letterM

 letterO

 letterP

 letterR

 letterS

 letterT

 overlay

 instruction1

 instruction2

 instruction3



## a part is a reusable piece of code. In this case, it gives for the

## 3 blocks the feedback



part myfeedback

 feedback

   text align left

   set &Total1 count ; select c8 == 1 && c1 == BLOCKNUMBER ## number of trials where there was a 2back item

   set &Total2 count ; select c8 > 1 && c1 == BLOCKNUMBER ## number of trials where there was NOT a 3back item

   set &Matches count     ; select c4 == 1 && c1 == BLOCKNUMBER ## number of matches

   set &Misses count      ; select c5 == 1 && c1 == BLOCKNUMBER ## number of misses

   set &FalseAlarms count ; select c6 == 1 && c1 == BLOCKNUMBER ## number of false alarms

   set &MatchesPerc      expression &Matches     / &Total1 * 100.0

   set &MissesPerc       expression &Misses      / &Total1 * 100.0

   set &FalseAlarmsPerc  expression &FalseAlarms / &Total2 * 100.0

   text -250 -200 "There were 25 trials in total in this block"

   text -250 -150 &Total1 ; prefix "Total trials that had a match:"

   text -250 -100 &Total2 ; prefix "Total trials that had no match:"

   text -250 -50 &Matches ; prefix "Number of correctly matched items:"

   text -250 -0 &Misses ; prefix "Number of missed items:"

   text -250  50 &FalseAlarms ; prefix "Number of false alarms:"

   text -250 100 &MatchesPerc ; prefix "Percentage correct matches:" ; postfix " %"

   text -250 150 &MissesPerc  ; prefix "Percentage missed items:" ; postfix " %"

   text -250 200 &FalseAlarmsPerc ; prefix "Percentage false alarms:" ; postfix " %"

   text -250 250 "Click mouse to continue and show data"

   wait_for_key mouse

 end



task nback_learning

 set &trialcount increase

 set $currentletter random 1 15 ## choose randomw letter, might be overridden

 ############################################################################

 ## is this condition a yes condition?

 set $memory random 1 &choosechance ## 1 in &choosechance trials will be matching trial

 ## if a 2back trial (there must have been at least 2 trials before for this to be possible)

 if $memory == 1 && &trialcount > 2

   set $currentletter &nback2

   set $requiredresponse 1 ## this is a MATCH, so response is required

 fi

 ## if a NON 2back trial

 if $memory != 1 || &trialcount <= 2 ## chose a letter but not that of 2 trials ago

   set $currentletter random 1 15

   while $currentletter == &nback2 ## choose anything but NOT that of 2 back

     set $currentletter random 1 15

   while-end

   set $requiredresponse 2 ## this is a NON-match, so people need to withhold

 fi

 ############################################################################

 ## this part is the only part that is different between learning and non-learning

 draw off

   show bitmap $currentletter ## stimulus 1

   ## now show previous trials

   if &trialcount > 1

     show bitmap &nback1 -100 0     # show 1-back left of stimulus

     show bitmap overlay -100 0  # greyed out

   fi

   if &trialcount > 2

     show bitmap &nback2 -200 0     # show 2-back left of stimulus

     show bitmap overlay -200 0  # greyed out

   fi

 draw on

 ######################################################################

 readmouse l 1 &maxrt ## click the first bitmap in this task

 ############################################################################

 ## the different possible response outcomes

 ##

 if $requiredresponse == 1 and STATUS != TIMEOUT

   set $score 1 ## means good

   set $match 1

   sound sound_good

 fi

 if $requiredresponse == 1 and STATUS == TIMEOUT

   set $score 0 ## means wrong -- miss

   set $miss 1

   sound sound_bad

 fi

 if $requiredresponse == 2 and STATUS == TIMEOUT

   set $score 1 ## means good

 fi

 if $requiredresponse == 2 and STATUS != TIMEOUT

   set $score 0 ## means wrong

   set $false_alarm 1

   sound sound_bad

 fi

 #

 ######################################################################

 #

 set $extrawait expression &maxrt - RT ## how much time is left between max RT and now?

 delay $extrawait ## wait until letter has been on screen total of 2000 ms

 clear screen

 delay 2000 ## wait 2000 ms

 #

 ### now save the letter for next trial

 #

 set &nback2 &nback1

 set &nback1 $currentletter

 ### save the data

 save BLOCKNUMBER &trialcount $score $match $miss $false_alarm RT $memory $currentletter &nback1 &nback2



task nback_normal

 set &trialcount increase

 set $currentletter random 1 15 ## choose randomw letter, might be overridden

 ############################################################################

 ## is this condition a yes condition?

 set $memory random 1 &choosechance ## 1 in &choosechance trials will be matching trial

 ## if a 2back trial (there must have been at least 2 trials before for this to be possible)

 if $memory == 1 && &trialcount > 2

   set $currentletter &nback2

   set $requiredresponse 1 ## this is a MATCH, so response is required

 fi

 ## if a NON 2back trial

 if $memory != 1 || &trialcount <= 2 ## chose a letter but not that of 2 trials ago

   set $currentletter random 1 15

   while $currentletter == &nback2 ## choose anything but NOT that of 2 back

     set $currentletter random 1 15

   while-end

   set $requiredresponse 2 ## this is a NON-match, so people need to withhold

 fi

 ############################################################################

 ## this part is the only part that is different between learning and non-learning

 draw off

   show bitmap $currentletter ## stimulus 1

 draw on

 ######################################################################

 readmouse l 1 &maxrt ## click the first bitmap in this task

 ############################################################################

 ## the different possible response outcomes

 ##

 if $requiredresponse == 1 and STATUS != TIMEOUT

   set $score 1 ## means good

   set $match 1

   sound sound_good

 fi

 if $requiredresponse == 1 and STATUS == TIMEOUT

   set $score 0 ## means wrong -- miss

   set $miss 1

   sound sound_bad

 fi

 if $requiredresponse == 2 and STATUS == TIMEOUT

   set $score 1 ## means good

 fi

 if $requiredresponse == 2 and STATUS != TIMEOUT

   set $score 0 ## means wrong

   set $false_alarm 1

   sound sound_bad

 fi

 #

 ######################################################################

 #

 set $extrawait expression &maxrt - RT ## how much time is left between max RT and now?

 delay $extrawait ## wait until letter has been on screen total of 2000 ms

 clear screen

 delay 2000 ## wait 2000 ms

 #

 ### now save the letter for next trial

 #

 set &nback2 &nback1

 set &nback1 $currentletter

 ### save the data

 save BLOCKNUMBER &trialcount $score $match $miss $false_alarm RT $memory $currentletter &nback1 &nback2



block training

 set &trialcount 0 # make sure you use this again if you have another block

 message instruction1 mouse

 message instruction2 mouse

 tasklist

   nback_learning 25

 end

 part myfeedback



block normal1

 set &trialcount 0 # make sure you use this again if you have another block

 message instruction3 mouse

 tasklist

   nback_normal 25

 end

 part myfeedback



block normal2

 set &trialcount 0 # make sure you use this again if you have another block

 message instruction3 mouse

 tasklist

   nback_normal 25

 end

 part myfeedback