Hjalmar Sundén (1908–1993) was a Swedish psychologist, known for his contributions to the psychology of religion and for his development of "role theory".
After receiving his doctorate, Sundén, unable to obtain a university post for some time, taught psychology and religion at various schools in the Stockholm region.
Sundén's role theory has been influential in the psychology of religion as taught by the Dutch psychologist Jan van der Lans.
His student Nicolette Hijweege used Sundén's role theory for PhD-research on conversion among Dutch reformed Christians.
Wulff notes a study by Lars (1987), in which people were undergoing Zen training were more likely to report a mystical experience if they had a religious frame of reference.