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- Margaret Mahler
- George Mandler
- Jean Matter Mandler
- James G. March, cognitive organizational psychology
- Ruth Marshall
- Abraham Maslow, Maslow's hierarchy of needs
- William Masters and Virginia Johnson, sexology
- Rollo May
- Rufus May
- David McClelland
- James McClelland
- William McDougall
- Patrick J McGrath
- Phil McGraw
- John Money
- Peter McGuffin
- David McNeill
- Jacques Mehler
- Andrew Meltzoff
- Ronald Melzack
- Wolfgang Metzger
- David E. Meyer
- Stanley Milgram
- Alice Miller
- Munesuke Mita
- George A. Miller
- Neal E. Miller, biofeedback
- Brenda Milner
- Arnold Mindell, Process Oriented Psychology
- Walter Mischel
- Jacob L. Moreno, Psychodrama
- C. Lloyd Morgan, canon
- John Morton
- Orval Hobart Mowrer
- Georg Elias Muller
- Henry Murray
- Hugo Munsterberg
Read more about this topic: List Of Psychologists