PsyToolkit

## Copyright: see http://www.psytoolkit.org/copyright.html
##
## this is a two back task
##
## the total time window during which people can give a response is
## the intertrial interval + the stimulus display time
## the 500 + 2500 is a commonly used timing of events in nback tasks

options
  bitmapdir stimuli
  set &stimulus_display_time 500 # stimulus presentation
  set &iti 2500  # intertrial interval
  set &choosechance 3 # 1 in "choosechance" are matching. The higher the number, the fewer matches
  
fonts
  arial 18

bitmaps
  letterA ## 15 letters
  letterB
  letterC
  letterD
  letterE
  letterH
  letterI
  letterK
  letterL
  letterM
  letterO
  letterP
  letterR
  letterS
  letterT
  overlay
  error_feedback
  correct_feedback
  grey_feedback
  instruction1
  instruction2
  realblock1
  realblock2
  
part myfeedback
  feedback
    text align left
    set &Total1 count ; select c3 == 1 && c1 == BLOCKNUMBER ## number of trials where there was a 2back item
    set &Total2 count ; select c3 == 0 && c1 == BLOCKNUMBER ## number of trials where there was NOT a 3back item
    set &Matches count     ; select c5 == 1 && c1 == BLOCKNUMBER ## number of matches
    set &Misses count      ; select c6 == 1 && c1 == BLOCKNUMBER ## number of misses
    set &FalseAlarms count ; select c7 == 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 "Press button Q to continue"
    wait_for_key q
  end

## the "part" below is a piece of code used several times in the code.
## this is just a placeholder which is used in the last later on.
## see the PsyToolkit documentation on how "part" works in detail

part check_response
  if $requiredresponse == 0 and STATUS == TIMEOUT
    set $score 1  ## so far so good
  fi
  if $requiredresponse == 0 and STATUS != TIMEOUT
    set $score 0  ## wrongly pressed during letter presentation.
    set $false_alarm 1
    show bitmap error_feedback  ## red rectangle below and over letter
  fi
  if $requiredresponse == 1 and STATUS != TIMEOUT
    set $score 1  ## correctly pressed during letter presentation.
    set $match 1
    show bitmap correct_feedback  ## green rectangle below and over letter
  fi

task twoback
  keys m
  set &trialcount increase
  set $currentletter random 1 15 ## choose random letter out of the 15 options
  ############################################################################
  ## is this condition a yes condition?
  set $memory random 1 &choosechance ## random number for choosing condition
  ## if a 2back trial
  if $memory == 1 and &trialcount > 2
    set $currentletter &nback2
    set $requiredresponse 1 ## the m key needs to be pressed later, m=stands for Memory
    set $typeoftrial 1
  fi
  ## if a NON n-back trial
  if $memory != 1 or &trialcount <= 2 ## chose a letter but not that of 3 trials ago
    set $currentletter random 1 15
    while $currentletter == &nback2 ## choose anything but NOT that of 3 back
      set $currentletter random 1 15
    while-end
    set $requiredresponse 0 ## no key should be pressed
    set $typeoftrial 0
  fi
  ############################################################################
  draw off
    show bitmap $currentletter ## stimulus 1
    show bitmap grey_feedback  ## stimulus 2
  draw on
  readkey 1 &stimulus_display_time
  set $extrawait expression &stimulus_display_time - RT ## how much time is left between max RT and now?
  ##############################################################
  ## determine whether error was made during letter presentation
  ## people can only make mistake if pressing now when they should not
  ##############################################################
  set $score 0 ## this is the default, assume error
  part check_response
  set $my_rt RT
  ###########
  ## now wait remaining time if needed
  ###########
  delay $extrawait ## wait until letter has been on screen total of 760 ms, note this only happens if people already pressed
  clear 1 ## clear the letter from screen
  ###########
  ## now show nothing but allow response during ITI
  ###########
  if STATUS == TIMEOUT ## means people did not respond yet
    readkey 1 &iti
    set $my_rt expression RT + &stimulus_display_time
  fi
  part check_response
  ## if you pressed, then some time will be left; during that time, no need to further check keys anymore
  set $extrawait expression &iti - RT ## how much time is left between iti RT and now?
  ## now check if people missed
  if $requiredresponse == 1 and $score == 0
    set $miss 1
  fi
  delay $extrawait
  ### now save the letter for next trial
  set &nback2 &nback1
  set &nback1 $currentletter
  ### save the data
  save BLOCKNUMBER &trialcount $typeoftrial $score $match $miss $false_alarm $my_rt $memory $currentletter &nback1 &nback2

block training
  set &trialcount 0 # make sure you use this again if you have another block
  message instruction1
  message instruction2
  tasklist
    twoback 25
  end
  part myfeedback

block nback_real1
  set &trialcount 0 # make sure you use this again if you have another block
  message realblock1
  tasklist
    twoback 25
  end
  part myfeedback

block nback_real2
  set &trialcount 0 # make sure you use this again if you have another block
  message realblock2
  tasklist
    twoback 25
  end
  part myfeedback