By Paul Gilbert
By Daniel Nettle (Lecturer in Biological Psychology at the Open University)
By Peter Hollins
By Sigmund Freud
By Brian Parkinson, Agneta H. Fischer, Antony S.R. Manstead
By Vanessa Springora
By Leo Bormans
By Brené Brown
By Mel Collins, Jeremy Vine
By Jennifer Aaker, Naomi Bagdonas
By Max Lucado
By Andy McNab, Professor Kevin Dutton
By Gary Chapman, Ph.D.
By Glenda Fredman
By Ansembourg, Thomas d'
By Jill Dann
By R.L. Payne, Cary L. Cooper
By Prof Paul Ekman (Professor of Psychology)
By Sally Planalp (University of Montana)
By Gwyneth Lewis
By Claude Steiner, Paul Perry
By Bobby Duffy
By Paul R. Ehrlich, Stanford University, Robert E. Ornstein
By Carl Plantinga (Associate Professor of Theater Arts, Calvin College), Greg M. Smith (Instructor, Georgia State University)
By Sara Wengerd
By Joseph Ledoux
By Christiane Sanderson
By Nettle, Daniel
By Dawson, John W. Jr., Kellner, J.
By Daniel Gilbert