A Reply to the Methodological and Theoretical Concerns of Vidulich and Tsang

Major areas of concern expressed by Vidulich and Tsang (2007, this issue) concern the derivation of the Multiple Resources Questionnaire (MRQ), how well its items are grounded on performance trade-offs or other indications of their resource nature, and the representativeness of the resources. At heart these concerns question the validity of the approach, and so we are grateful for additional space to summarize, defend, and extend our position. The roots of the MRQ lie in factor analytic research undertaken to identify the set of processes predominantly lateralized to one hemisphere of the brain. The strength of this approach is that it provides strong empirical support for the orthogonal nature of the processes, because to an almost exclusive degree the factor analytic results indicate that lateral differences are uncorrelated across the identified processes. In turn that indicates that the neurological substrates of the processes are themselves independent, a highly desirable characteristic for processes to be included in a multiple resources model.