The effects of practice on speed of information processing using the Adjusting-Paced Serial Addition Test (Adjusting-PSAT) and the Computerized Tests of Information Processing (CTIP).

Three experiments were conducted to determine the effects of practice on the Adjusting-Paced Serial Addition Task (Adjusting-PSAT) (Tombaugh, 1999) and the Computerized Tests of Information Processing (CTIP) (Tombaugh & Rees, 2000). The Adjusting-PSAT is a computerized modification of the Paced Auditory Serial Addition Test (PASAT) (Gronwall, 1977) that makes the interval between digits contingent on the correctness of the response. This titration procedure permits a threshold value to be derived that represents the shortest presentation interval in which a person can process the digits to produce the correct sum. The CTIP consists of three reaction time tests that are progressively more difficult. Results showed that robust practice effects occurred with the Adjusting-PSAT, with the greatest increase in performance occurring on the first retest trial. Practice effects were equally prominent regardless of whether the first retest trial occurred 20A min, 1 week, or 3 months after the first administration. These gains were maintained for periods up to 6 months and were independent of modality of presentation (visual or auditory) and type of number list (easy or hard). In contrast to the findings with the Adjusting-PSAT, only minimal practice effects were observed with the CTIP. The major clinical implication of the study is that the high reliability coefficients for the CTIP, the lack of anxiety associated with its administration, and its insensitivity to variables such as numerical and verbal ability make the CTIP ideally suited for the serial evaluation of cognitive status. These characteristics also make the CTIP a viable alternative to the Adjusting-PSAT or PASAT for measuring speed of information processing. If the Adjusting-PSAT is administered repeatedly in clinical evaluations, a "dual baseline" or "run in" procedure should be used, with the second administration serving as the baseline measurement.