The American Psychological Association (APA) is the main professional organization of psychologists in the United States, and the largest psychological association in the world. It has over 157,000 members, including scientists, educators, clinicians, consultants, and students. It has 54 divisions, which function as interest groups for different subspecialties of psychology or topical areas. The APA has an annual budget of around $125 million.
Donald Olding Hebb was a Canadian psychologist who was influential in the area of neuropsychology, where he sought to understand how the function of neurons contributed to psychological processes such as learning. He is best known for his theory of Hebbian learning, which he introduced in his classic 1949 work The Organization of Behavior. He has been described as the father of neuropsychology and neural networks. A Review of General Psychology survey, published in 2002, ranked Hebb as the 19th most cited psychologist of the 20th century. His views on learning described behavior and thought in terms of brain function, explaining cognitive processes in terms of connections between neuron assemblies.
Lisa Feldman Barrett is a Canadian-American psychologist. She is a University Distinguished Professor of psychology at Northeastern University, where she focuses on affective science and co-directs the Interdisciplinary Affective Science Laboratory. She has received both of the highest scientific honors in the field of psychology, the William James Fellow Award from the Association for Psychological Science for 2025, and the Award for Distinguished Scientific Contributions from the American Psychological Association for 2021. Along with James Russell, she is the founding editor-in-chief of the journal Emotion Review. Along with James Gross, she founded the Society for Affective Science.
Patrick J. McGrath, OC, FRSC FCAHS is a Canadian psychologist noted for his contribution to research on childhood pain.
Robert Gifford is a former professor of Psychology and Environmental Studies. His main research interests are environmental psychology, social psychology and personality psychology. He has worked on nonverbal behavior and on climate change behavior barriers. Gifford is the author of five editions of Environmental Psychology: Principles and Practice, which has also been translated into Japanese, and edited Research Methods for Environmental Psychology (2016). From 2004 to 2016, he was the editor in chief of the Journal of Environmental Psychology. Gifford is also on the editorial board of Architectural Science Review. He has been president of the environmental divisions of the American Psychological Association, the International Association of Applied Psychology and the Canadian Psychological Association.
David Allen Wolfe is an academic, psychologist and author specializing in issues of child abuse, domestic violence, children and youth. His work includes the promotion of healthy relationships through school programs, with a major focus on the prevention of child abuse and neglect, bullying, dating violence, unsafe sex, substance abuse and other consequences of unhealthy relationships.
John Widdup Berry is a psychologist known for his work in two areas: ecological and cultural influences on behavior; and the adaptation of immigrants and indigenous peoples following intercultural contact. The first is broadly in the domain of cross-cultural psychology; the second is in the domain of intercultural psychology.
Patrick Henry (Pat) DeLeon is an American psychologist, former chief of staff for United States Senator Daniel Inouye and past president of the American Psychological Association (APA). He became an aide for Senator Inouye in 1973, when Inouye served on a committee investigating the Watergate scandal, and remained on the senator's staff for 38 years. After DeLeon's daughter survived meningitis in 1984, he was involved in the establishment of the Emergency Medical Services for Children program. DeLeon helped to create the nursing and pharmacy schools at the University of Hawaiʻi at Hilo.
Peter Suedfeld is a Hungarian-Canadian professor emeritus of psychology at the University of British Columbia.
David M. Regan is a Canadian psychologist, currently a Distinguished Professor Emeritus at York University and a Fellow of the Optical Society, American Academy of Optometry, Royal Society of Canada, and Canadian Psychological Association. From 1978 to 1983, he was York's I. W. Killam Research Professor.
Bryan Edward Kolb is a Canadian neuroscientist, neuropsychologist, researcher, author and educator. Kolb's research focuses on the organization and functions of the cerebral cortex.
The CPA Donald O. Hebb Award for Distinguished Contributions to Psychology as a Science is an annual award presented by the Canadian Psychological Association (CPA).
Kenneth D. Craig is a Canadian psychologist, educator and scientist whose research primarily concerns pain assessment, understanding pain in children and populations with communication limitations, and the social dimensions of pain.
Janel Gauthier is a Canadian psychologist with expertise in clinical psychology, human rights and ethics.
Mary J. Wright (1915-2014) was a Canadian psychologist who was a pioneer for women in psychology in Canada.
Roy B. Liddy was a Canadian psychologist and founding President of the Canadian Psychological Association.
Keith Stephen Dobson is a Canadian psychologist, academic, and researcher. With a long career at the University of Calgary in Canada, he now holds the title of Professor Emeritus, having served as a tenured Professor, Head of the Psychology Department, and Director of the Clinical Psychology program at the university.
Adrien Pinard (1916-1998) was a Canadian psychologist and noted researcher in developmental psychology.
Robert J. Vallerand is a Canadian social psychologist, academic and author. He is a Full Professor of Psychology at the Université du Québec à Montréal where he holds a Canada Research Chair in Motivational Processes and Optimal Functioning and is Director of the Research Laboratory on Social Behavior.
