This paper discusses the effect of usage experiences on the evaluation of waiting time when using ICT. In discussing waiting time, we assume an internal cognitive model based on the hypothesis that the evaluation of waiting is determined by comparing perceived waiting time with expected waiting time. The effect of usage frequencies on expected waiting time is also incorporated. To investigate this model, we conducted two experiments to evaluate waiting time during e-mail transmission with and without an attachment. Both results support our hypothesis and showed that the subjective evaluation scores were maximized at a particular frequency of usage. The results are useful for implementing concrete measures in system design and also for providing a general strategy for waiting time issues in the real world. The results also reveal the need to consider users' frequency of usage in service design.

Key words: waiting time, ICT, cognitive model, time perception