Does the scoring of late responses affect the outcome of the paced auditory serial addition task (PASAT)?

The Paced Auditory Serial Addition Task (PASAT) is a cognitive task purported to measure working memory, speed of information processing, and sustained and divided attention (Spreen, O. & Strauss, E. (1998). A compendium of neuropsychological tests: administration, norms, and commentary (2nd ed.). New York, NY: Oxford University Press.) The current study examined whether treating late responses on the PASAT as correct or as incorrect can significantly affect the outcome of the test in individuals with Multiple Sclerosis (MS). Subjects consisted of 59 individuals with MS and 37 healthy controls (HC). Scoring method was found to affect the number of individuals who were considered impaired on the PASAT. When participants were penalized for late responses significantly more participants, in both groups, were found to be impaired on the 2 s trial of the task (MS: p < 0.01; HC: p < 0.05). Results indicate that that the specific scoring of the PASAT should be reported in studies that use the test.