Gardner's formulation of PAS is critiqued as lacking a scientific basis, and as a hypothesis whose proponents have failed to meet the scientific burden of proof to merit acceptance. The first publications about PAS were self-published and not peer reviewed, and though subsequent articles have been published in peer reviewed journals, most have consisted of anecdotal evidence in the form of case studies; in addition, the limited research into PAS has lacked evidence of its validity and reliability. The lack of objective research and replication, falsifiability, and independent publication has led to claims that PAS is pseudoscience or junk science. Proponents of PAS concur that large scale systematic controlled studies into PAS's validity and reliability are required, supplementing a single small study in 2004 which suggested practitioners could come to a consensus based on written reports.
