According to the CP interview, Thoresen's "scholarly work, professional service, teaching, and mentorship have motivated many counseling psychologists to radically expand their areas of inquiry.
He was among the first to focus counseling on observable behaviors and to apply psychological science and interventions to physical problems in medical settings.
They worked together on the Recurrent Coronary Prevention Project, which followed 1013 heart attack survivors for 4.5 years to determine effects from altering their coronary-prone (type A) behavior patterns.
Thoresen was responsible "to help design and direct the psychological treatment program based on a behavioral self-control perspective" (p. 282).
The study showed, "for the first time, within a controlled experimental design, that altering type A behavior reduces cardiac morbidity and mortality in post infarction patients" (p. 653).