While reading the post by Val in Australia I thought of Debi Bocar and her
reserch and study of just this sort of problem. She is currently pursing her
doctorate in education and psychology at the University of Okalahoma.  She
may have published on this subject or would quite certainly share information.
Her mailing address is:
Debi Leslie Bocar
Lactation Consultant Services
11320 Shady Glen Road
Oklahoma City. OK 73162
USA

I learn SO MUCH on LACTNET.  Hope this helps.
Lynnette Stiles RNC, IBCLC in NW Arkansas