Raving about Ravens : modelling speed-accuracy in intelligence tests

The effect of time pressure on performance on intelligence tests is a long standing problem. In this study a computerised version of the Ravens Advanced Progressive Matrices was administered using 3 different forms of instructions: control, speed pressure, and accuracy pressure. Analyses used Rasch measures of participant ability and item difficulty, and the time each participant took to solve each problem. Raw scores were, surprisingly, more useful than Rasch measures. The time pressure group were faster but scored less well than the other two groups. Raw score had a small but significant correlation with total test time. Brighter participants took less time for easy items, but more time for hard items, which were both slower and more variable than easier items. Mean and SD were more consistent for total time than for either correct or error time. Effective models will need to incorporate these diverse results