The validity of d prime as a working memory index: results from the "Bergen n-back task".

The n-back task is frequently used as an experimental paradigm in imaging studies of working memory. This study aimed to investigate whether the Bergen 2-back task is suitable for use in desktop assessment of patients with schizophrenia. Looking at the psychometric properties of the task, including the newly added measure of discriminability, d prime (d '), our analyses confirmed that the 2-back d ' is the preferred measure of working memory dysfunction in desktop assessment compared to the Digit Span Backward and the Letter-Number Sequencing subtests from the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III). d ' has the advantage of capturing executive skills needed to perform mental operations in patients with schizophrenia, without being influenced by demographic variables or IQ.