When scoring algorithms matter: effects of working memory load on different IAT scores.

In most process accounts of the Implicit Association Test (IAT), it is assumed that compatible and incompatible IAT blocks require different amounts of working memory capacity (WMC) and recruit executive functions such as task switching and inhibition to different extents. In the present study (N= 120), cognitive load during the completion of an IAT was experimentally manipulated by means of an oral random-number generation secondary task. Cognitive load led to slower latencies and more errors, especially in the incompatible block. However, different IAT scores, including conventional scores and D-scores, were affected differentially by the load manipulation: scores based on raw data of task performance such as latencies and errors were increased whereas scores that use transformations such as log-latency scores and D-scores were decreased. A number of analyses shed light on the reasons for the unexpected dissociation between scoring algorithms. Remarkably, external correlations of the IAT scores were not affected by the experimental manipulation.