3) Dumbbell shrugs.

Also an exercise targeting only the trapezius.
Subject stands with his arms hanging down the sides, palms turned inwards with a dumbbell in each. He then shrugs his shoulders as high as he can, hold the position a bit at the top of the motion then slowly lower the weights.
Extra considerations: - back needs to be kept straight to avoid injury
- be careful to execute the exercise correctly, pay special attention to not bending your arms thus helping in bringing the weight up.
- try to move ONLY your shoulders