The Effects of List Difficulty and Modality of Presentation on a Computerized Version of the Paced Serial Addition Test (PSAT)

The Paced Serial Addition Test (PSAT) presents a series of digits at different speeds with the requirement that the two most recent numbers be added together. Although the PSAT is a relatively difficult test, its level of difficulty may be decreased by changing the number list to make the answers simpler and by presenting the digits visually rather than aurally. In view of this, the present experiment varied both task difficulty (easy vs. hard) and mode of presentation (visual vs. auditory). Task difficulty was manipulated by using two different lists composed of single digits whose answers ranged between 2 and 10 (easy) or 2 and 18 (hard). All stimuli were presented by computer which permitted measurement of response latencies, as well as correctness of responding. The results showed that mode of presentation, but not task difficulty, produced highly significant effects. Additional evidence showed that the ability to compute answers to simple addition problems must be considered as a modulator variable. ...