Does random time interval generation interfere with working memory executive functions?

We report here the results of four dual-task experiments in which a random time interval generation task was performed concurrently with a memory task. The random generation task was designed to interfere with executive functions, as defined in the working memory model of Baddeley and Hitch (1974). In four experiments, concurrent execution of this task was found to impair recall in a supra-span memory task with numbers or with consonants (Experiment 1), in an adaptive forwards span task (Experiment 3) and in an adaptive backwards span task (Experiment 4). Comparisons of random performance under dual-task conditions in the four experiments to single-task random performance revealed increasing deviations from randomness with the degree of primary task-load. We argue that our findings corroborate the thesis that the random time interval generation task interferes with executive functions while the load on slave systems and other processing components is low.