The Portland Digit Recognition Test

Abstract

Abstract The Portland Digit Recognition Test (PDRT) is a valid measure of motivation to perform poorly on memory tests that is useful in forensic evaluations. Validation data and clinical use are described. The PDRT meets standards of the Daubert decision for the admissibility of scientific data into the courtroom by expert witnesses. The PDRT has been tested in scientific studies, results of scientific studies have appeared in peer-reviewed journals, the error rate is known, and it is well accepted in the scientific community according to published articles. A survey showed that 27% of forensic neuropsychologists reported using the PDRT consistently (Essig, Mittenberg, Petersen et al., 2001). Cutoff scores are available with 100 percent specificity, and these cutoff scores have moderate sensitivity for detection of poor motivation. The strongest psychometric evidence of faking a memory deficit occurs when a forced choice test result is significantly worse than chance. Data indicate that worse than chance results occur regularly on the PDRT.