Interpretations of Task Difficulty in Terms of Resources: Efficiency, Load, Demand, and Cost Composition.

Abstract

Abstract : The effect of task difficulty on performance can be conceptualized within a theory which posits that performance depends on the use of resources from a single pool. When the difficulty of a task is said to increase it may mean either that resources invested in it can now do less (i.e., a decrease in efficiency), or are now required to do more (i.e., an increase in load), or have now less time to do it (i.e., a stricter limit on processing duration). Either way, difficulty should most often interact with resource investment in such a way that effects of resource investment on quality or speed of performance are more pronounced the easier the task. If the processing system is viewed as comprised of a number of mechanisms each having its own capacity, whicy may be considered as a separate resource, then a difficulty manipulation may affect differentially the use of each of those capacities. If in a dual-task situation manipulation of the difficulty of one task affects the use of a mechanism which is not required by the other task, processing of the latter may remain intact under some circumstances. To get a complete picture of how difficulty affects dual-task performance, it is proposed to manipulate task preferences as well as difficulty parameters and to present their joint effect by families of POCs. Application of this methodology to the study of pursuit tracking is briefly described and interpreted in terms of multiple resources.