They should probably qualify what kind of art seems to reduce anxiety. I could line a patient waiting room with H.R. Giger paintings, but that might not achieve the same result:
https://slowsoulburn.files.wordpress.com/2014/02/hr_giger_du...
http://2.bp.blogspot.com/-lwoGruDK7ww/TWaPQYPMQ9I/AAAAAAAAAc...
https://slowsoulburn.files.wordpress.com/2014/02/hr-giger_00...
https://pickadolla.files.wordpress.com/2014/05/elp___h_r_gig...