Paced Auditory Serial Addition Test (PASAT)

Background

The Paced Auditory Serial Addition Test (PASAT), introduced by Dorothy Gronwall in 1977, is a popular cognitive behavioral assessment tool of processing speed and working memory asking participants to work on simple addition tasks under time pressure. The PASAT presents participants with a series of spoken digits at a constant pace. Participants have to respond with the sum of the last two presented digits as fast as possible. This task requires that participants a) stay on task, b) constantly update their working memory with the last two presented digits and c) quickly process the digits to produce the required sum at the same time. Different levels of the task are run (usually 4), each time increasing the speed with which the digits are presented. The task is considered challenging and stressful but has been shown to be highly sensitive to even minor cognitive impairments.

The original design of the PASAT collects oral responses, the Inquisit implementation asks participant to quickly select a response button that reflects the current sum instead.

Task Procedure

A participant is presented with a circle of response buttons from 1 to 18. Every 2 seconds or so the computer speaks a digit. As soon as the participant has calculated the sum of the last two presented digits, they need to press the respective response button as fast as possible before the next digit is spoken.

A level is completed after 60 digits (not counting the first). During the regular PASAT, the first level presents the digits every 2.4 seconds. The presentation rate decrease over the following levels, ending with a presentation rate of 1.2 seconds during the fourth and final level. The PASAT can also be run with an adaptive design that adjusts the presentation rate based on mean correct response times.

What it Measures

The Paced Auditory Serial Addition Test (PASAT) is a measure of processing speed and working memory.

Psychological Domains

• Sustained Attention: Ability to maintain focus on a continuous repetitive task
• Working Memory: Ability to keep relevant information in working memory
• Processing Speed: Ability to quickly process information held in working memory
• Executive Control: Ability to continuously update working memory while suppressing irrelevant information (e.g. the previous sum)

Main Performance Metrics

• Number of Correct Responses: Main indicator of processing speed and working memory function
• Omission Errors: Number of missed/skipped responses
• Number of Addition Errors: Number of incorrectly entered sums
• Number of Suppression Errors: Number of times the entered sum was derived from adding the last digit to the previous sum

Psychiatric Conditions

Performance on the PASAT tends to be impaired in patients with the following psychiatric conditions:

• Multiple Sclerosis (MS)
• Traumatic Brain Injury (TBI)
• Dementia
• Major Depressive Disorder
• Attention Deficit Hyperactivity Disorder (ADHD)