Continuous Performance Task

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A Continuous Performance Task/Test, or CPT, is a psychological test which measures a person's sustained and selective attention. Sustained attention is the ability to maintain a consistent focus on some continuous activity or stimuli, and is associated with impulsivity. Selective attention is the ability to focus on relevant stimuli and ignore competing stimuli. This skill is associated with distractibility.^[1]

There are a variety of CPTs, the more commonly used being the Test of Variables of Attention (T.O.V.A.) and the Conner's CPT-II. These attention tests are often used as part of a battery of tests to understand a person's 'executive functioning' or their capacity to sort and manage information. They may also be used specifically to support a diagnosis of Attention Deficit Disorder

[edit] Test Administration

Although the tests may vary in terms of length and type of stimulus used, the basic nature of the tests remain the same. Clients are told that they will see a series of letters presented on a screen. They are told to click a button (or computer mouse) only when they see the "target" stimulus, for instance the letter "X." The person must refrain from clicking if they see any other letter presented. To increase the difficulty, some tests change the task so that the person must only click if they see the letter "A" before the letter "X."^[1]

Other tests may use numbers, symbols, or even sounds, but the basic task has the same concept. The T.O.V.A. is similar but is administered on a separate device rather than a computer screen. It uses geometric shapes rather than letters so that reading levels do not play a part in the scoring. The T.O.V.A. also differs in that is has two sections. The first section is a "low brain stimulation task" where the targets are infrequently presented. The boring nature of this task pulls for "errors of omission" when the person is distracted and not responding to the target. The second half of this test is a "high brain stimulation task" in which targets are frequently presented. This task pulls for "errors of commission" since a person may expect to see a target and impulsively respond.^[2]

[edit] Test Scoring

While scoring varies from test to test, there are three main scores that are used.

Reaction times This measures the amount of time between the presentation of the stimulus and the client's response.

Omission errors This indicates the number of times the target was presented, but the client did not respond/click the mouse. High omission rates indicate that the subject is either not paying attention (distractibility) to stimuli or has a sluggish response.

Commission errors This score indicates the number of times the client responded but no target was presented. A fast reaction time and high commission error rate points to difficulties with impulsivity. A slow reaction time with high commission and omission errors, indicates inattention in general.

These client's scores are compared with the normative scores for the age, group and gender of the person being tested.^[1]

[edit] References