The extent and nature of the ability to control the allocation of mental resources between the components of a dual task was investigated in three separate experiments. Using a variable priority (demand) methodology it was found that subjects could manipulate their performance level, however their ability to meet specific demand levels was limited. Training subjects under single or dual-task conditions using a wide range of task demand significantly improved dual task performance and degree of control over resource allocation as compared to performance following practice under a narrow range of task demands or under single task fixed demand conditions. Single task performance among all groups improved to the same degree. It was concluded that training subjects under a wide range of task demands increases the range of performance levels over which mental resources can be flexibly allocated for those tasks and improves time sharing performance. Implications for the design of training for complex task performance are discussed.
Virtually Perfect Time Sharing in Dual-Task Performance: Uncorking the Central Cognitive Bottleneck