Introduction

Sometimes, a normal spatial compatibility effect can be "reversed". That happens when people respond more quickly in the stimulus-response incompatible condition than in the stimulus-response compatible situation. The ABBA effect, first described by Stoet & Hommel (1999), is an example of this.

A more detailed description of the task can be found here.

In short, in the ABBA effect, you carry out two different simple responses to two different stimuli. The first stimulus (called Stimulus A) is viewed, a response is planned but withheld until the end of the trial. Then a second stimulus (called Stimulus B) is shown and the participant must respond immediately (Response B). Then, the participant must finish the trial with the final response A, which should hopefully still linger in short term memory. The whole trial takes around 6 seconds. Below is a schematic image of the idea.

About this implementation

There are 10 training trials and 100 main trials. The trials might feel as happening in a somewhat "slow" manner. This is because there is a delay of a few seconds between stimulus A and B (during which you just need to wait). At the end of the demo, you will see your own response-incompatibility effect.

Run the demo

In the demo, you will use four keys of your keyboard, the a and s on the left side, and the k and l on the right side. You plan a response (one or two key presses with the s or k button), and then later you need to respond directly with a a or l button press. Detailed instructions are in the demo.

Click here to run a demo of the ABBA task

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

1

location of planned response (response A, "L" or "R")

2

location of the immedeate response (response B, "L" or "R")

3

location of the immedeate response (response B, 1 or 2)

4

number of responses for response A

5

first response time (to response B)

6

first response time for response A (the planned response)

7

second response time for response A (if a second response is needed)

PsyToolkit code

Click to expand the PsyToolkit script code (part of zip file below) 
# based on the paradigm of Stoet & Hommel 1999

options
  set &delay1     750  # how long the first stimulus is being shown
  set &delay2     3000 # how long the delay between stimulus 1 and 2 is
  set &errordelay 2000 # how long the error message is displayed for
  bitmapdir stimuli

fonts
  arial 18

bitmaps
  planleft1
  planright1
  planleft2
  planright2
  pressleft
  pressright
  cue
  instruction1
  instruction2
  instruction3
  instruction4
  fix1
  fix2
  fix3
  errormsg
  welldone
  tooslow
  wrongkeys
  readyrealblock
  readytrainingblock

# @1: planned response A, immedeate response B (as letter L,R),
# immedeate response as number (1,2), number of responses in response
# A

table abba_table
  "L L 1 1" planleft1  3 1 pressleft   1
  "L L 1 2" planleft2  3 2 pressleft   1
  "L R 2 1" planleft1  3 1 pressright  2
  "L R 2 2" planleft2  3 2 pressright  2
  "R L 2 1" planright1 4 1 pressleft   1
  "R L 2 2" planright2 4 2 pressleft   1
  "R R 1 1" planright1 4 1 pressright  2
  "R R 1 2" planright2 4 2 pressright  2

task abba
  table abba_table
  keys a l s k
  delay 1000 # intertrial interval
  set $tmpcheck 0 # a help variable for checking the memorized response later on
  set $trialcorrect 0 # if 1, then all responses in trial were correct
  ### animated fixpoint
  show bitmap fix1
  delay 150
  show bitmap fix2
  delay 150
  show bitmap fix3
  delay 150
  clear 3
  delay 150
  clear 2
  delay 150
  clear 1
  delay 150
  ###
  show bitmap @2
  delay &delay1
  clear -1
  delay &delay2
  show bitmap @5
  readkey @6 1000
  set $rt1     RT
  set $status1 STATUS
  clear -1
  if $status1 == WRONG ## response 1
    show bitmap errormsg
    show bitmap wrongkeys 0 -200
    delay &errordelay
    clear -1 -2
  fi
  if $status1 == TIMEOUT ## response 1
    show bitmap errormsg
    show bitmap tooslow  0 -200
    delay &errordelay
    clear -1 -2
  fi
  ## now, only if the first was correct contininue with getting further responses
  if $status1 == CORRECT
    ###
    show bitmap cue
    ### ---------------> now wait for one or two key presses
    readkey @3 1000
    set $rt2 RT
    set $status2 STATUS
    readkey @3 400 ## should actually result in timeout if only 1 button press needed
    set $rt3 RT
    set $status3 STATUS
    ### ---------------> now process correctness
    if @4 == 2 && $status3 == CORRECT #
      set $tmpcheck 1 ## this means, 2nd button required and correct
    fi
    if @4 == 1 && $status3 == TIMEOUT #
      set $tmpcheck 1 ## this means, subject pressed twice, but should only have memorized once
    fi
    if $status2 != CORRECT || $tmpcheck == 0
      clear -1 # remove cue from screen
      show bitmap errormsg
      delay &errordelay
      clear -1
    fi
    if $status2 == CORRECT && $tmpcheck == 1 # positive feedback
      show bitmap welldone
      delay &errordelay
      set $trialcorrect 1
    fi
  fi
  save @1 $rt1 $rt2 $rt3 $status1 $status2 $status3 &delay1 &delay2 $trialcorrect

block training
  pager instruction1 instruction2 instruction3 instruction4
  message readytrainingblock
  clear screen
  tasklist
    abba 10
  end

block for_real
  message readyrealblock
  clear screen
  tasklist
    abba 100
  end
  feedback
    text align left
    set &MyMean mean c5       ; select c13 == 1
    set &Compatible mean c5   ; select c13 == 1 && c3 == 1
    set &Incompatible mean c5 ; select c13 == 1 && c3 == 2
    set &EffectSize expression &Incompatible - &Compatible
    text -380 -50 &MyMean       ; prefix "Average response speed of first response                       : " ; postfix " ms"
    text -380 -10 &Compatible   ; prefix "Average response speed of first response in compatible trials  : " ; postfix " ms"
    text -380  30 &Incompatible ; prefix "Average response speed of first response in incompatible trials: " ; postfix " ms"
    text -380 100 &EffectSize   ; prefix "Incompatible - Compatible response speed: " ; postfix " ms"
    text    0 200 "Press space bar to continue"
  end

Download

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.

Further reading

  • Stoet, G. and Hommel, B. (1999). Action planning and the temporal binding of response codes. Journal of Experimental Psychology: Human Perception and Performance, 25, 1625-1640.

  • Stoet, G. & Hommel, B. (2002). In Prinz, W. & Hommel, B. (Eds.). Interaction between feature binding in perception and action. Common mechanisms in perception and action: Attention and Performance, Vol. XIX (pp. 538-552). Oxford: Oxford University Press.