The d2 test is a cancellation test to measure attention, visual scanning, and processing speed. It is the most frequently used test of attention in Europe. Although it has been validated using factor analytic techniques and correlational analyses, its fit to item response theory models has not been examined. We evaluated the fit of the d2 test to the Rasch Poisson Counts Model (RPCM) by examining the fit of six different scoring techniques. Only two scoring techniques-concentration performance scores and total number of characters canceled-fit the RPCM. The individual items fit the RPCM, with negligible differential item functioning across sex. Graphical model check and likelihood ratio test confirmed the overall fit of the two scoring techniques to RPCM.
Keywords: Rasch Poisson Counts Model; d2 test; selective attention; sustained attention; validity.