effect on affiliation does not occur when one of the dyad is synchronizing their movements to something outside the dyad. This is known as interpersonal synchrony. There has been dispute regarding the true effect of synchrony in these studies. Research in this area detailing the positive effects of synchrony, have attributed this to synchrony alone; however, many of the experiments incorporate a shared intention to achieve synchrony. Indeed, the Reinforcement of Cooperation Model suggests that perception of synchrony leads to reinforcement that cooperation is occurring, which leads to the pro-social effects of synchrony. More research is required to separate the effect of intentionality from the beneficial effect of synchrony. Uses Synchronization is important in digital telephony, video and digital audio where streams of sampled data are manipulated. Synchronization of image and sound was an important technical problem in sound film. More sophisticated film, video, and audio applications use time code to synchronize audio and video. In movie and television production it is necessary to synchronize video frames from multiple cameras. In addition to enabling basic editing, synchronization can also be used for 3D reconstruction In electric power systems, alternator synchronization is required when multiple generators are connected to an electrical grid. Arbiters are needed in digital electronic systems such as microprocessors to deal with asynchronous inputs. There are also electronic digital circuits called synchronizers that attempt to perform arbitration in one clock cycle. Synchronizers, unlike arbiters, are prone to failure. (See metastability in electronics). Encryption systems usually require some synchronization mechanism to ensure that the receiving cipher is decoding the right bits at the right time. Automotive transmissions contain synchronizers that bring the toothed rotating parts (gears and splined shaft) to the same rotational velocity before engaging the teeth. Flash synchronization synchronizes the flash with the shutter. Some systems may be only approximately synchronized, or plesiochronous. Some applications require that relative offsets between events be determined. For others, only the order of the event is important. See also Notes References External links J. Domański "Mathematical synchronization of image and sound in an animated film" Systems