Early experiments in the 1990s yielded mixed results on the effectiveness of interoceptive exposure.[4][5] Throughout the 21st century, scientists began to create treatment protocol to help those with Panic Disorder. Barlow and Craske (2007) constructed a popular treatment procedure in which therapists use a low dose of IE therapy along with controlled breathing skills.[6] However, scientists still question whether a low-dose IE therapy or a more intensive approach is more effective.