Using roleplay to assist use case checking is not strictly necessary, but it does harness several human skills. It uses the abilities of the people playing the roles to identify with the roles, which can often cause them to focus more intently on the user intention or the system responsibility, and to detect problems. It also uses the ability of a critical audience to follow the dialog, and brings into play skills developed in understanding stories. These skills help people to detect discontinuities or assumptions, and so detect possible problems in the use case. Use case roleplay makes adds more fun and variety into the activity, and these also heighten attention.