Introduction

Negative priming is a slow down and increase in error rate when responding to an object that had to be ignored previously (Tipper, 1985). For a good review, see the paper by Mayr & Buchner, (2007).

Check the lesson about negative priming with more details than provided here.

About this implementation

This demo uses the idea of the Dalrymple-Alford & Budayr (1966) paper.

Run the demo

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

1

Blockname

2

Blocknumber

3

Color of word

4

Color inkcolor (except for training block)

5

Table row of used table (this way, you can determine exactly which stimulus was shown)

6

The key that was pressed

7

Status (1=correct, 2=wrong, 3=timeout)

8

Reaction time

PsyToolkit code

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

## in the stroop stimuli, the filename is WORD+font color
## thus: yellowred is the work "yellow" in red color

bitmaps
  titlepage
  instruction1
  instruction2
  instruction3  
  start_block1
  start_block2
  start_block3  
  correct
  mistake
  fixpoint
  yellowgreen  
  yellowblue   
  yellowred    
  redyellow    
  redgreen     
  redblue      
  greenyellow  
  greenblue    
  greenred     
  blueyellow   
  bluegreen    
  bluered      

fonts
  arial 18

# table: write condition,stimulus,response

table training
  "red square    " 255 0 0 1
  "yellow square " 255 255 0 4
  "blue square   " 30 144 255 3
  "green square  " 0 255 0 2
  
table neutral
  "red blue    " redblue      3
  "yellow green" yellowgreen  2
  "green blue  " greenblue    3
  "red yellow  " redyellow    4
  "blue green  " bluegreen    2
  "yellow red  " yellowred    1
  "yellow blue " yellowblue   3
  "green red   " greenred     1  
  "blue yellow " blueyellow   4
  "red green   " redgreen     2  
  "green yellow" greenyellow  4
  "blue red    " bluered      1

table negative
  "yellow green" yellowgreen  2
  "green yellow" greenyellow  4
  "red green   " redgreen     2
  "blue red    " bluered      1
  "yellow blue " yellowblue   3
  "red yellow  " redyellow    4  
  "green red   " greenred     1
  "blue green  " bluegreen    2
  "red blue    " redblue      3
  "yellow red  " yellowred    1
  "blue yellow " blueyellow   4
  "green blue  " greenblue    3

task neutralpriming
  table neutral
  part rest_of_task

task negativepriming
  table negative
  part rest_of_task

part rest_of_task
  keys r g b y
  delay 500
  show bitmap fixpoint # stimulus 1
  delay 200
  clear 1 # remove fixpoint 
  delay 100
  show bitmap @2 # stimulus 2
  readkey @3 2000
  clear 2 # remove stimulus 2
  if STATUS == CORRECT
    show bitmap correct # stimulus 3 (feedback)
  fi
  if STATUS != CORRECT  # stimulus 3 (feedback)
    show bitmap mistake
  fi
  delay 500
  clear 3 # remove feedback stimulus
  save BLOCKNAME BLOCKNUMBER @1 TABLEROW KEY STATUS RT

task colortraining
  table training
  keys r g b y
  delay 500
  show bitmap fixpoint # stimulus 1
  delay 200
  clear 1 # remove fixpoint 
  delay 100
  show rectangle 0 0 100 50   @2 @3 @4
  readkey @5 2000
  clear 2 # remove stimulus 2
  if STATUS == CORRECT
    show bitmap correct # stimulus 3 (feedback)
  fi
  if STATUS != CORRECT  # stimulus 3 (feedback)
    show bitmap mistake
  fi
  delay 500
  clear 3 # remove feedback stimulus
  save BLOCKNAME BLOCKNUMBER @1 TABLEROW KEY STATUS RT

block training
  message titlepage
  message instruction1
  message instruction2
  message instruction3  
  message start_block1
  tasklist
    colortraining 20
  end

block neutral
  message start_block2
  tasklist
    neutralpriming 12 fixed  # run the neutral stimuli
  end

block negative
  message start_block3
  tasklist
    negativepriming 12 fixed  # run the neutral stimuli
  end
  feedback
    set &Training mean c8 ; select c2 == 1 && c7 == 1
    set &Neutral  mean c8 ; select c2 == 2 && c7 == 1
    set &Negative mean c8 ; select c2 == 3 && c7 == 1    
    set &Difference expression &Negative - &Neutral
    text 0 -225 "Your speed..."
    text 0 -125 &Training ;  prefix "in training block (block 1): "
    text 0 -25  &Neutral ;  prefix "in neutral condition (block 2): "
    text 0 75    &Negative ;  prefix "in negative priming condition (block 3): "
    text 0 175  &Difference ; prefix "Difference is: "
    text 0 275 "Press space key to end"
  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

  • Dalrymple-Alford, E.C. & Budayr, B. (1966). Examination of some aspects of the Stroop color word test. Perceptual & Motor Skills, 23, 1211-1214.

  • Mayr, S. & Buchner, A. (2007). Negative Priming as a Memory Phenomenon. Journal of Psychology, 215(1), 35-51.

  • Tipper, S.P. (1985). The negative priming effect: Inhibitory priming by ignored objects. Quarterly Journal of Experimental Psychology: Human Experimental Psychology, 37A, 571-590.