Different difficulty manipulations interact differently with task emphasis: Evidence for multiple resources

To test the notion of multiple resources, a 2-dimensional pursuit tracking task paired with a letter-typing task, the difficulty of which was manipulated by varying cognitive and motor factors, was administered to 6 right-handed males (19-25 yrs old). The manipulation of task priority had a large effect on the performance of the 2 tasks, which indicates that they compete for resources. Both types of typing difficulty manipulations affected typing performance, but only motor difficulty interacted with priorities. Results are interpreted to indicate that in joint performance, typing and tracking compete mainly for motor-related but not for cognitive resources. Consistent with the multiple resources concept, the letter-typing task is argued to require at least 2 kinds of resources. (14 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).