Specializing in diagnostics, Harrower developed a scale allowing practitioners to predict which patients would profit from psychotherapy.
[5]: 89 Ogden recommended her to his friend the Gestalt psychologist Kurt Koffka, who directed the psychology laboratory at Smith College in Massachusetts.
[1] On the invitation of Beatrice Edgell she returned to Bedford College in 1932 as a temporary senior lecturer, filling in for one year after the accidental death of her former teacher Victoria Hazlitt.
[5]: 89 At the MNI she worked with Wilder Penfield, and was involved as a psychologist in the pioneering neural stimulation studies that led to the development of the Montreal procedure for treating epilepsy.
[1] Early in the Second World War, Harrower received a grant from the Canadian National Research Council to develop a large-scale Rorschach test.
[5]: 90 The group test was used to screen military recruits based on their responses when shown a standard series of inkblot designs.
The subjects were given a list of possible interpretations from which to choose and a high number of "neurotic" choices was seen as necessitating a "psychiatric check-up".
[9][10] In 1941 Harrower moved from Montreal to Madison, Wisconsin where her husband, neurosurgeon Theodore Erickson, had obtained a position at the University of Wisconsin–Madison medical school.
[1] She received funding from the Macy Foundation to continue developing and training psychologists in the use of large-scale Rorschach tests.
[1] During the course of her practice she used her diagnostic techniques on over 1,600 patients, keeping records of each consultation, and followed up with the treating therapists to develop a scale predicting the likelihood of successful therapy.
[13]: 8 [14] She also did consulting work for organizations such as the Children’s Court of Manhattan, the National Multiple Sclerosis Society, and the Unitarian-Universalist Church.
[3] Harrower left New York and joined the faculty of the University of Florida in Gainesville in 1967, teaching clinical psychology.
Based on this conclusion, she cautioned that "well-integrated, productive and secure personalities are no protection against being sucked into a vortex of myth and deception, which may ultimately erupt into the commitment of horror on a grand scale".