The BFA (Boston Museum of Fine Arts, also MOMA has this program as well) has a program call the Visual Thinking Curriculum (I believe this is the correct name) which is steeped in all kinds of research and data...just start googling Visual Thinking Curriculum and you will come up with lots of data on the benfits of reflective thinking in visual art.
How fortunate that your principal asked you to present such an important topic that can demonstrate how students can use those aesthetic judgement skills across the curriculum!