CPT: Continuous Performance Test

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Test for sustained attention and concentration.

This is the classic paradigm for measuring sustained attention and concentration with alphanumeric stimuli. A large number of stimuli appears on the screen one by one. A response (space bar, mouse click, touch screen or external button box) is only requested if a certain combination of 2 stimuli (target) is presented: for example the letter X preceded by the letter A. This combination occurs very infrequent (standard in 10% of the trials, but the percentage can be reduced or increased).

The presentations can be divided over a number of blocks within which the targets occur to the same extent, so that time-on-task effects can be studied. Optionally, a target for a series length of 3 can be chosen (for example only respond to an X if this is preceded by A and then Z). Both the targets and the complete stimulus set can be set to letters, digits, other punctuation, or all symbols mixed together. Even the WingDings symbols can also serve as stimuli. Stimuli can be presented sequentially (one by one), but also as “news ticker”, with the next stimulus on the right side of the screen (figure above). The maximum “width” of the news ticker is also adjustable.

In the report the percentage correct and the average RT and standard deviation, as well as the percentage of false negatives (FN) and number of false positives (FP) are calculated per block. A distinction is also made between different types of FPs. For example, setting the target to “X after A” may cause errors such as: “only A”, “A no X”, “only X” and random errors. Based on the frequency of the different types of errors, and according to theoretical assumptions the outcome might be interpreted as impulsivity (relatively many “A no X” and “only A” errors), or attention deficit (relatively many “only X” errors, random errors and many FNs).

An English language version is available.

Normative information is available from two groups of people with mild cognitive impairment (children up to 19 years, and adults), as well as patients with a serious mental illness. There are 5 norm variables: percent correct, median RT, standard deviation of RT, percentage FN and number of FP. Based on these 5 variables, an interpretative report can be generated.

Literature:

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, 343-350.

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