The operation of achieving authenticated key agreement between two human-operated devices over a short range wireless communication channel, such as Bluetooth or WiFi, is known as “pairing.” The devices being paired are ad hoc in nature, i.e., they can not be assumed to have a prior context (such as pre-shared secrets) or a common trusted on- or off-line authority. However, the devices can generally be connected using auxiliary physical channel(s) (such as audio or visual) that can be authenticated by the user(s) of the devices. These authenticatable channels can be used to form a basis for pairing. In this paper, we present the results of a user study of a technique used to pair two devices (such as two cell phones) which have good quality output interfaces in the form of a display, speaker, and/or vibration.