Roles, needs and diversity affect teamwork because of individual differences. In Sociology, roles are what an individual does when he/she is in this aspect or setting. Needs are what an individual has to have in order to survive. Diversity is where individuals have different backgrounds. When these are understood, teamwork can flourish and ideas can be significant.
I believe the answer is: Communication is collaborative
Which mean that in order for a communication to be formed, both the giver and receiver of the message should play their own role properly.
The giver of the message had the role to ensure the delivery of the information happen clearly, and the receiver had the role to ensure that he/she provide the necessary attention and cognitive process to receive the message.
I would say that the independent variable is the violent film, as it is what is being changed in the experiment.
