Cooperative decision-making process was volitional coordinated information search in pursuit of a shared choice between two persons. This study compared Pairs of participants with Single participants in choice tasks. To compare Pairs with Singles, we monitored the amount and sequence of information acquired during decision making using a computerized process tracing tool. We also examined the recall of aspects after choice and evaluation of their decision. Female undergraduates (N=36) carried out the task that participants were asked to choose a package tour among 4 tours or 8 tours, using one visual display terminal. The results showed that Pairs tended to take more various attributes into consideration, and that Pairs increased the amount of time needed to get information. In addition, Pairs showed that aspects of the chosen alternative were remembered better than not chosen alternatives. This result was interpreted as a difficulty of information sharing between Pairs. In the light of the result Pairs tented to evaluate more available information on choice tasks, we suggested that this difficulty was due to an increase in information load for Pairs.
