Endogenous vs exogenous cueing

Introduction

People typically respond faster to target stimuli whose location has previously been "cued". However, this effect turns around when the interval between cue and target is over 300 m (Klein, 20000). This latter effect is known as Inhibition Of Return (IOR).

Interestingly, IOR is not observed when the cue is endogenous and when no saccades are being made.

In a study by Filotheo and colleagues (1997), healthy individuals and people suffering from Parkinson’s disease were compared in both endogenous and exogenous cueing. The prediction is that when people are not making saccades (e.g., because they have been instructed to keep fixating on the fixation point), there should only be IOR in the exogenous condition. But is that true? Try it yourself!

About this implementation

This implementation requires a numeric keyboard!

Run the demo

In this example, you will

Click here to run a demo

Data output file

In PsyToolkit, the data output file is simply a textfile. The save line of the PsyToolkit experiment script determines what is being saved in the data output file. Typically, for each experimental trial, you would have exactly one line in your text file, and each number/word on that line gives you the information you need for your data analysis, such as the condition, response speed, and whether an error was made.

Meaning of the columns in the output datafile. You need this information for your data analysis.

Colum	Meaning BLOCKNAME &training $cuetype $valid $SOA $waitkeytime $tooearly $cue $target STATUS RT
1	Name of block
2	Training (0=no training block, 1=training block)
3	Type of cue (1=endogenous, 2=exogenous)
4	cue validity (0=invalid, 1=valid)
5	soa (time between cue and target, 50, 150, 250, 1000 ms)
6	the time the participant waited to press the central button
7	was response too early (0=no, 1=yes)
8	cue position (1=left, 2=top, 3=right, 4=bottom)
9	target position (1=left, 2=top, 3=right, 4=bottom)
10	Status (1=correct, 2=wrong, 3=timeout)
11	Reaction time (ms)

PsyToolkit code

Click to expand the PsyToolkit script code (part of zip file below)

# Based on a study by Filotheo et al: Journal of the International
# Neuropsychological Society (1997), 3, 337–347.  Adapted for teaching
# using PsyToolkit, http://www.psytoolkit.org by G. Stoet, 2015.

options
  fullscreen
  bitmapdir stimuli
  escape

fonts
  arial 12

bitmaps
  box_grey
  box_yellow
  cue_down
  cue_left
  cue_right
  cue_up
  press5
  fixpoint1
  fixpoint2
  fixpoint3
  fixpoint4
  fixpoint_green
  targetstim
  real
  happy
  sad
  slow
  tooearlywarning
  instructions1
  instructions2
  instructions3
  instructions4
  training_endo
  training_exo
  real_endo
  real_exo
  numlocktest
  numlockquestion
  numlockconfirmation

table numlocktable
  cue_up     0 -200 3
  cue_down   0  200 5
  cue_left   -200 0 2
  cue_right  200  0 4

task numlocktester
  table numlocktable
  keys kp5 kp4 kp8 kp6 kp2
  show bitmap press5
  readkey 1 20000
  clear -1
  show bitmap @1 @2 @3
  readkey @4 20000
  clear -1
  if STATUS == CORRECT
    show bitmap happy
    delay 500
    clear -1
  fi
  if STATUS != CORRECT
    show bitmap numlockquestion
    delay 5000
    clear -1
  fi

######################################################################
## notes:
## the implementation does not use a table, but instead does
## everything using the random function.
## in the endogenous condition (arrow points at cue or not,
## 80% validity)
######################################################################

## in the exogenous task, the cue is the box itself (bright)
## the validity is only 50%

task exogenous  ## cue => box yellow border
  keys kp5 kp4 kp8 kp6 kp2
  set $cuetype 2 # 1 = endo ; 2 = exo
  set $tooearly 0
  set $SOA random from 50 150 250 1000
  ## choose valid/invalid
  set $valid random from 1 0 ## this means 50%, valid=1,invalid=0
  if $valid == 1     # if valid, cue and target are the same
    set $cue random 1 4
    set $target $cue
  fi
  if $valid == 0 # if not valid, cue and target must be different
    set $cue random 1 4
    set $target random 1 4
    while $cue == $target
      set $target random 1 4
    while-end
  fi
  #############################################
  show bitmap box_grey -200 0
  show bitmap box_grey    0 -200
  show bitmap box_grey  200 0
  show bitmap box_grey    0  200
  delay 100
  show bitmap press5
  readkey 1 50000
  set $waitkeytime RT
  clear -1
  ##############################################
  show bitmap fixpoint1
  delay 150
  show bitmap fixpoint2
  delay 150
  show bitmap fixpoint3
  delay 150
  show bitmap fixpoint4
  delay 150
  ###################################show 1 of 4 cues
  if $cue == 1
    show bitmap box_yellow -200 0
  fi
  if $cue == 2
    show bitmap box_yellow 0 -200
  fi
  if $cue == 3
    show bitmap box_yellow  200 0
  fi
  if $cue == 4
    show bitmap box_yellow 0 200
  fi
  ##################################################
  readkey 1 $SOA # wait and ensure no key has been pressed
  if STATUS != TIMEOUT
    set $tooearly 1
    show bitmap tooearlywarning
    delay 1000
    clear -1
  fi
  ##################################################
  # now show the target, but only if not too early
  if $tooearly == 0
    if $target == 1
      show bitmap targetstim -200 0
      set $expected_keynum 2
    fi
    if $target == 2
      show bitmap targetstim 0 -200
      set $expected_keynum 3
    fi
    if $target == 3
      show bitmap targetstim 200 0
      set $expected_keynum 4
    fi
    if $target == 4
      show bitmap targetstim 0 200
      set $expected_keynum 5
    fi
    #####################################################
    readkey $expected_keynum 5000
    clear -1 -2
    ######################################################################
    # feedback
    if STATUS == CORRECT
      show bitmap happy
      delay 500
      clear -1
    fi
    if STATUS == WRONG
      show bitmap sad
      delay 500
      clear -1
    fi
    if STATUS == TIMEOUT
      show bitmap slow
      delay 500
      clear -1
    fi
  fi ## (from tooearly)
  ######################################################################
  # intertrial interval
  delay 500
  save BLOCKNAME &training $cuetype $valid $SOA $waitkeytime $tooearly $cue $target STATUS RT

task endogenous ## with arrows
  keys kp5 kp4 kp8 kp6 kp2
  set $cuetype 1 # 1 = endo ; 2 = exo
  set $tooearly 0
  set $SOA random from 50 150 250 1000
  ## choose valid/invalid
  set $valid random from 1 0 0 0 0 ## this means 20%
  if $valid == 1     # if valid, cue and target are the same
    set $cue random 1 4
    set $target $cue
  fi
  if $valid == 0 # if not valid, cue and target must be different
    set $cue random 1 4
    set $target random 1 4
    while $cue == $target
      set $target random 1 4
    while-end
  fi
  #############################################
  show bitmap box_grey -200 0
  show bitmap box_grey    0 -200
  show bitmap box_grey  200 0
  show bitmap box_grey    0  200
  delay 100
  show bitmap press5
  readkey 1 50000
  set $waitkeytime RT
  clear -1
  ##############################################
  show bitmap fixpoint1
  delay 150
  show bitmap fixpoint2
  delay 150
  show bitmap fixpoint3
  delay 150
  show bitmap fixpoint4
  delay 150
  ###################################show 1 of 4 cues
  if $cue == 1
    show bitmap cue_left
  fi
  if $cue == 2
    show bitmap cue_up
  fi
  if $cue == 3
    show bitmap cue_right
  fi
  if $cue == 4
    show bitmap cue_down
  fi
  ##################################################
  readkey 1 $SOA # wait and ensure no key has been pressed
  if STATUS != TIMEOUT
    set $tooearly 1
    show bitmap tooearlywarning
    delay 1000
    clear -1
  fi
  ##################################################
  # now show the target, but only if not too early
  if $tooearly == 0
    if $target == 1
      show bitmap targetstim -200 0
      set $expected_keynum 2
    fi
    if $target == 2
      show bitmap targetstim 0 -200
      set $expected_keynum 3
    fi
    if $target == 3
      show bitmap targetstim 200 0
      set $expected_keynum 4
    fi
    if $target == 4
      show bitmap targetstim 0 200
      set $expected_keynum 5
    fi
    #####################################################
    readkey $expected_keynum 5000
    clear -1 -2
    ######################################################################
    # feedback
    if STATUS == CORRECT
      show bitmap happy
      delay 500
      clear -1
    fi
    if STATUS != CORRECT
      show bitmap sad
      delay 500
      clear -1
    fi
    if STATUS == TIMEOUT
      show bitmap slow
      delay 500
      clear -1
    fi
  fi ## (from tooearly)
  ######################################################################
  # intertrial interval
  delay 500
  save BLOCKNAME &training $cuetype $valid $SOA $waitkeytime $tooearly $cue $target STATUS RT

######################################################################
# blocks (this is really where the experiment starts
######################################################################

block numlocktest
  message numlocktest
  tasklist
    numlocktester 8
  end
  message numlockconfirmation

block train_endo
  pager instructions1 instructions2 instructions3 instructions4
  message training_endo
  set &training 1
  tasklist
    endogenous 50
  end

block endo
  set &training 0
  message real_endo
  tasklist
    endogenous 100
  end

block train_exo
  set &training 1
  message training_exo
  tasklist
    exogenous 50
  end

block exo1
  set &training 0
  message real_exo
  tasklist
    exogenous 100
  end

block exo2
  set &training 0
  message real_exo
  tasklist
    exogenous 100
  end
  feedback # as the final thing, we show feedback
    text align left
    set &EndoValid50     mean c11 ; select c2 == 0 && c3 == 1 && c4 == 1 && c5 == 50   && c10 == 1
    set &EndoValid150    mean c11 ; select c2 == 0 && c3 == 1 && c4 == 1 && c5 == 150  && c10 == 1
    set &EndoValid250    mean c11 ; select c2 == 0 && c3 == 1 && c4 == 1 && c5 == 250  && c10 == 1
    set &EndoValid1000   mean c11 ; select c2 == 0 && c3 == 1 && c4 == 1 && c5 == 1000 && c10 == 1    
    set &EndoInvalid50   mean c11 ; select c2 == 0 && c3 == 1 && c4 == 0 && c5 == 50   && c10 == 1
    set &EndoInvalid150  mean c11 ; select c2 == 0 && c3 == 1 && c4 == 0 && c5 == 150  && c10 == 1
    set &EndoInvalid250  mean c11 ; select c2 == 0 && c3 == 1 && c4 == 0 && c5 == 250  && c10 == 1
    set &EndoInvalid1000 mean c11 ; select c2 == 0 && c3 == 1 && c4 == 0 && c5 == 1000 && c10 == 1    
    #
    set &ExoValid50      mean c11 ; select c2 == 0 && c3 == 2 && c4 == 1 && c5 == 50   && c10 == 1
    set &ExoValid150     mean c11 ; select c2 == 0 && c3 == 2 && c4 == 1 && c5 == 150  && c10 == 1
    set &ExoValid250     mean c11 ; select c2 == 0 && c3 == 2 && c4 == 1 && c5 == 250  && c10 == 1
    set &ExoValid1000    mean c11 ; select c2 == 0 && c3 == 2 && c4 == 1 && c5 == 1000 && c10 == 1    
    set &ExoInvalid50    mean c11 ; select c2 == 0 && c3 == 2 && c4 == 0 && c5 == 50   && c10 == 1
    set &ExoInvalid150   mean c11 ; select c2 == 0 && c3 == 2 && c4 == 0 && c5 == 150  && c10 == 1
    set &ExoInvalid250   mean c11 ; select c2 == 0 && c3 == 2 && c4 == 0 && c5 == 250  && c10 == 1
    set &ExoInvalid1000  mean c11 ; select c2 == 0 && c3 == 2 && c4 == 0 && c5 == 1000 && c10 == 1    
    #
    text -300 -280 &EndoValid50     ; prefix "Valid endogenous Cues with SOA = 50: " ; postfix " ms"
    text -300 -250 &EndoValid150    ; prefix "Valid Endogenous Cues with SOA = 150: " ; postfix " ms"    
    text -300 -220 &EndoValid250    ; prefix "Valid Endogenous Cues with SOA = 250: " ; postfix " ms"
    text -300 -190 &EndoValid1000   ; prefix "Valid Endogenous Cues with SOA = 1000: " ; postfix " ms"
    text -300 -160 &EndoInvalid50   ; prefix "Invalid Endogenous Cues with SOA = 50: " ; postfix " ms"
    text -300 -130 &EndoInvalid150  ; prefix "Invalid Endogenous Cues with SOA = 150: " ; postfix " ms"    
    text -300 -100 &EndoInvalid250  ; prefix "Invalid Endogenous Cues with SOA = 250: " ; postfix " ms"
    text -300  -70 &EndoInvalid1000 ; prefix "Invalid Endogenous Cues with SOA = 1000: " ; postfix " ms"
    text -300  -40 &ExoValid50      ; prefix "Valid Exogenous Cues with SOA = 50: " ; postfix " ms"
    text -300  -10 &ExoValid150     ; prefix "Valid Exogenous Cues with SOA = 150: " ; postfix " ms"    
    text -300   20 &ExoValid250     ; prefix "Valid Exogenous Cues with SOA = 250: " ; postfix " ms"
    text -300   50 &ExoValid1000    ; prefix "Valid Exogenous Cues with SOA = 1000: " ; postfix " ms"
    text -300   80 &ExoInvalid50    ; prefix "Invalid Exogenous Cues with SOA = 50: " ; postfix " ms"
    text -300  110 &ExoInvalid150   ; prefix "Invalid Exogenous Cues with SOA = 150: " ; postfix " ms"    
    text -300  140 &ExoInvalid250   ; prefix "Invalid Exogenous Cues with SOA = 250: " ; postfix " ms"
    text -300  170 &ExoInvalid1000  ; prefix "Invalid Exogenous Cues with SOA = 1000: " ; postfix " ms"
    text -300  250 "PRESS SPACE BAR TO CONTINUE..."
  end

Download

The PsyToolkit code zip file

If you have a PsyToolkit account, you can upload the zipfile directly to your PsyToolkit account. Watch a video on how to do that. If you want to upload the zipfile into your PsyToolkit account, make sure the file is not automatically uncompressed (some browsers, especially Mac Safari, by default uncompress zip files). Read here how to easily deal with this.

Endogenous vs exogenous cueing

Introduction

About this implementation

Run the demo

Data output file

PsyToolkit code

Download

Further reading