Medium preference and medium effects in person-person communication

How does user's media preference vary with communication situation, and does media preference in a certain situation, and does media preference in a certain situation predict actual performance? Preference study shows that user's choice of communication medium seems to follow a common pattern, relatively independent of the communication task at hand - Video being most preferred, text chat the least. Parallel effect studies of person-person communication show, however, that actual task outcome varies with the type of task performed.