NonX Continuous Performance Test (NonX-CPT)

Background

The NonX Continuous Performance Test (NonX Cpt), more commonly known as the Conners CPT 3, is a widely used variation of the classic Continuous Performance Test created in 1985 by Keith Conners as a diagnostic tool for Attention Deficit Hyperactivity Disorder (ADHD). Early versions of the test (then called the "Conners' Computerized CPT") ran on IBM-compatible PCs and were the first computerized measure of ADHD. Multi-Health Systems released the first commercial version of the test (Conners CPT-II) in 2000. In 2014, a substantially revised version was released (Conners CPT 3) which differed from earlier versions in that it presented a higher proportion of go than no/go trials. The CPT 3 is designed to assess individuals 8 years and older.

Task Procedure

A continuous series of letters are flashed on the screen for 250 ms, one at a time at a variable rate. Participants are instructed to press a response key if and only if a letter other than 'X' is presented. Reponses must be made before the next stimulus is presented to be considered correct.

Participants first perform 3 practice blocks of 20 trials consisting of 12 go and 8 no-go trials, with error messages presented after incorrect responses. Following practice, participants perform 6 blocks of 60 trials, each of which runs 3 sub-blocks of 20 trials with presentation rates of one letter per 1, 2, or 4 seconds. Each subblock consists of 18 go trials and 2 no-go trials. No breaks are provided between blocks or sub-blocks.

What it Measures

The NonX CPT is a measure of sustained attention.

Psychological Domains

• Sustained Attention: Ability to maintain focus on a continuous repetitive task over a long time.
• Inhibitory Control: Ability to withold a response to non-target stimuli

Main Performance Metrics

• Omission Error Rate: Proportion of targets missed (inattentiveness, attentional lapse)
• Commission Error Rate: Proportion of responses to non-targets (impulsivity, inhibitory control)
• Hit Reaction Time (HRT): Average response time (processing speed)
• Variability: Standard deviation of HRTs (highly sensitive to ADHD)
• D Prime: Ability to discriminate targets from non-targets (attentional capacity)
• Response Bias (β): Indicating a impulsive or cautious style of responding
• HRT Block Change: Performance changes over time (sustained attention)

Psychiatric Conditions

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

• Attention Deficit Hyperactivity Disorder (ADHD)
• Traumatic Brain Injury (TBI)
• Post-Concussion Syndrom