The question of how to interpret IAT scores comes up a lot, so I'd post an explanation here to help demystify this subject.
As a participant completes the IAT, Inquisit keeps a running trial-by-trial tally of d, which is the standard metric used to interpret IAT results. The final d score for a given participant thus appears on the last row of data for that participant. Inquisit reports 3 d scores, which appear in the last 3 columns labeled "expressions.da", "expressions.db", and "expression.d".
Expressions.da is the d score from just the practice (i.e., first) blocks for both pairings.
Expressions.db is the d score from just the test (i.e. second) blocks for both pairings.
Expressions.d is the d score for both practice and test blocks. This is the score that is typically reported as the measure of association.
D scores can be positive or negative. A positive score indicates an association of targetA with attributeA and targetB with attributeB. A negative score indicates an association of targetA with attributeB and targetB with attributeA. Translating the score into a preference or attitude thus depends on how you have assigned your real world categories to these 4 groups. You can determine the mappings by looking at the topmost section of your IAT script, where you'll see the <item> definitions for each category.
For example, let's say you are studying implicit attitudes towards neckties vs ascots, where neckties are targetA, ascots are targetB, pleasant words are attributeA, and unpleasant words are attributeB. A positive d score would indicate the participant is more of a necktie sort of person. A negative score would indicate an affinity for the classic and elegant ascot look. A score of zero would indicate no preference.
Inquisit also records all of the raw responses and response latencies for every trial so that you have the option of running post hoc analyses on the data (e.g., to experiment with different methods of handling outliers). We offer an SPSS command script that provides a good starting point for this, which you can download from our IAT page:
If you run the script as is, you'll get exactly the same d scores as those described above, but the script can be easily edited to do custom analyses.