Continuous Performance Task (CPT)

Continuous performance task - sustained attention and target detection

The Continuous Performance Task (CPT) is a long, monotonous test of sustained attention. The participant watches a stream of stimuli and must respond to a defined target while withholding responses to non-targets, usually for several minutes. Because it demands continuous vigilance, the CPT is a standard tool for studying attention lapses and inhibitory control.

The CPT Procedure

Stimuli (letters, numbers, shapes, or abstract symbols) appear in a rapid, continuous stream. The participant's rule is simple but must be held throughout:

Respond when a target appears (e.g., the letter X, or any letter except X).
Withhold when a non-target appears.

A common variant is the AX-CPT: the participant must respond only when an X follows an A (a cue–probe pair), and withhold otherwise. This separates the cost of maintaining a cue in memory (the A) from the cost of resolving the probe, dissociating sustained attention from working-memory-guided control.

Performance is scored on:

Hits — correct responses to targets.
Commissions — false alarms to non-targets (impulsivity / failed inhibition).
Omissions — missed targets (vigilance failures).
Mean RT and RT variability — slowing and fluctuation over time.

What the CPT Measures

The CPT probes two related but distinct capacities:

Vigilance — maintaining detector readiness across a long, boring run (captured by omissions and RT drift).
Inhibitory control — withholding a prepotent response to frequent non-targets (captured by commissions).

Performance typically degrades as the run continues, revealing the cost of sustained effort. The AX-CPT further localizes deficits to cue-maintenance versus response-conflict components.

Relationship to Other Paradigms

The Psychomotor Vigilance Task is a purer reaction-time probe of the same vigilance construct.
The Sustained Attention to Response Task (SART) also combines Go/No-go with sustained attention but with a different response rule.
The Mackworth Clock Task is an early vigilance paradigm.
The Go/No-go Task shares the respond/withhold structure without the long-run vigilance demand.

Why It Matters

The CPT is widely used in clinical assessment of attention (ADHD, traumatic brain injury, schizophrenia) because its hit/commission/omission profile maps onto distinct attentional impairments. Its factorial variants let researchers dissect which attentional component is impaired.

Methodology

Methodology: This topic is part of the experimental workflow covered in Experimentology. For the relevant methods, see Design (target/non-target ratio and cue–probe structure as independent variables), Measurement (hit rate, false-alarm rate, and d′ via signal detection), and Inference (modeling omissions versus commissions).

Psychomotor Vigilance Task - Reaction-time vigilance probe
Sustained Attention to Response Task - Go/No-go sustained attention
Mackworth Clock Task - Classic vigilance task
Go/No-go Task - Respond/withhold inhibition
Signal Detection Theory - Modeling hits and false alarms

Implementation

A jsPsych implementation of the AX-CPT (the cue–probe variant of the Continuous Performance Task) is part of the ExpFactory experiments collection, which provides browser-ready sustained-attention paradigms.

References

Rosvold, H. E., Mirsky, A. F., Sarason, I., Bransome, E. D., & Beck, L. H. (1956). A continuous performance test of brain damage. Journal of Consulting Psychology, 20(5), 343-350.