Although Decision Support Systems (DSSs) have been in use since the early seventies, there is as yet no strong theoretical base for predicting how a DSS will influence decision making. Furthermore, the findings of various empirical studies on the outcomes of DSS use are often contradictory. Consequently, there is a need in the Decision Support Systems field for theories or explanatory models to formulate hypotheses, to conduct research in a directed, parsimonious manner and to interpret findings in a coherent way. This will assist both academics and practitioners interested in the use of information systems to support managerial workers. This paper proposes the use of a cognitive effort model of decision making to explain decision maker behavior when assisted by a DSS. The central proposition is that specific features can be incorporated within a DSS that will alter the effort required to implement a particular strategy, and thus influence strategy selection by the decision maker. This was investigated in a series of three experimental studies which examined the influence of computer based decision aids on decision making strategies. In the three experiments, subjects were given different degrees of support to deal with various components of cognitive effort (processing effort, memory effort and information tracking effort) associated with the strategies applicable to preferential choice problems. The results show that decision makers tend to adapt their strategy selection to the type of decision aids available in such a way as to reduce effort. These results suggest that the assumption that decision makers use a DSS exclusively to maximize decision quality is open to question. DSS studies which consider the joint effects of effort and quality, or control one while manipulating the other, are more likely to provide consistent and interpretable results.
