Continuous Performance Test - Identical Pairs (CPT-IP)

Background

The Continuous Performance Test, Identical Pairs (CPT-IP) is a variation of the classic Continuous Performance Test (CPT) developed in 1988 by Barbara Cornblatt and colleagues at the New York State Psychiatric Institute to study participants at risk for schizophrenia. Cornblatt sought to create a measure that was more difficult and reliable than the original. Programmed on an Apple II Plus, the CPT-IP was developed and refined as part of the New York High-Risk Project, a 26-year longitudinal study starting in 1971 that tracked children of parents with and without schizoprenia or affective disorders.

Task Procedure

A series of 4-digit numbers are flashed on the screen for 50 ms, one at a time at a rate of one per second. Participants are instructed to press a response key if and only if a given number is presented twice in a row. Reponses must be made before the next stimulus is presenteed to be considered correct. For each sequence of 150 numbers, there are 30 are target trials requiring a response, and 28 catch trials on which the number presented is similar but the same as the preceding number.

Participants perform 30 practice trials followed by 150 test trials.

What it Measures

The CPT-IP 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
• Working Memory: Ability to remember previous stimulus while processing the current one
• Processing Speed: How quickly stimuli are evaluated

Main Performance Metrics

• D Prime: Ability to discriminate targets from non-targets (attentional capacity)
• Hit Rate: Proportion of correct responses to targets
• False Alarm Rate: Proportion of responses to non-targets (impulsivity, inhibitory control)
• Omission Error Rate: Proportion of targets missed (distractibility, attentional lapse)
• Reaction Time: Average response time (processing speed)
• Response Bias: Log beta, indicating a lenient or cautious approach to responding

Psychiatric Conditions

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

• Schizophrenia
• Bipolar Disorder
• Major Depressive Disorder
• Attention Deficit Hyperactivity Disorder (ADHD)