Scoring the IAT (case 12779)

[jarvis24]

[the following edited reply is taken from a summary post to the SPSP mailing list by Joseph Comeau]

I am sure you will get a lot of replies but if you don't, call me and i will walk you through easily changing the Inquisit syntax to work with Direct RT (all you need to do is transform the variables so they are named the same as in the syntax and check a couple of procedural things in your direct rt program). My cell is *** (I am a post doc of Mahzarin Banaji's).

This all assumes that you programmed and collected data using a 7-block IAT

1. Merge all of your DirectRT files with the filemerge software that Blair Jarvis (from Empirisoft) that comes included with DirectRT (save the merged file as ".csv" -- it will pull into SPSS much better than .txt).
2. Pull the big huge file into SPSS.
3. In DirectRT, your trial #rs must begin with #1 (and go to whatever). SO: if the range in DirectRT is 5-380, you need to transform it to range from 1-376.
4. In DirectRT, your block numbers need to range from 1-7 (i recall default coding the blocks 0-6 so you will want to transform the numbers to range from 1-7)
5. In DirectRT your errors vs correct responses may have been coded
   differently than the syntax needs. Your errors must be coded = 0 and correct responses = 1
6. A critical issue is one of IAT order. the IAT syntax thinks you ran all odd subjects as order #1 (e.g., black+bad & white+good) and all even subjects as order #2 (e.g., black+good & white+bad; see syntax from the IAT SPSS syntax below).
7. In the syntax file, you MUST change the order variable syntax or compute an appropriate "order variable" in your SPSS data file and then remome the part of the syntax that looks like this:
   
   

   *If order of the combined
   tasks differs in some other fashion, provide an appropriate replacement
   * for the following line (which works when order differs for odd and even
   subject numbers) .
   COMPUTE ORDER = mod(subj, 2) .
   RECODE ORDER (0=2) .

8. Regardless of what DirectRT named your variables, there are 5 key variables that the SPSS IAT syntax needs to read in order to
   run. SO: you will want:
   
   

   subject variable to become --> subj
   block variable --> block
   trial variable = trial
   response time variable = lat 
   correct response variable = cor

9. You do not need to rename anything else (looking at the syntax, you may
   think you need to add additional stuff in there... you can, but it doesn't
   affect how the syntax runs and is not necessary).
10. Attached is an SPSS IAT scoring syntax file to use.
11. After running for a minute or so (you will see a bunch of SPSS files opening and closing) the output of the syntax file will be a file with a bunch of variables in it. The variables you really want to use are: D600 (in DirectRT you must add the "error penalty" in the scoring; see Greenwald et al., 2003 for an explanation). the other D variables you may wish to look at are the practice600 and the test600 (which will separate your IAT score into the practice blocks vs. the test blocks). You may also wish to look at the overall errors-- if any person has 35% or more errors, you shouldn't use their data.
12. The direction of your scored IAT variable is determined by how you
    programmed the experiment. Assuming you changed the ORDER variable as indicated above, the syntax scores everything to conform to blocks 3&4 minus blocks 6&7 (and, of course, smaller numbers here mean faster responding).
    
    This should give you all you need after a good reading of Greenwald et al.'s scoring algorithm paper. Good luck!!!

Dana R. Carney, Ph.D.
Department of Psychology
Harvard University

Note: Attached is the basic IAT syntax from Tony Greenwald's site with some variable recode syntax at the top (I made some notes for the user, also). I actually used this syntax for my own data and I am pretty sure my instructions are correct (I have had to do this a few times but differently each time as I am usually helping someone else and everyone programs differently).