Aside from the pressures Joy/Hulga imposes on herself, in part the result of her missing leg and her own self-absorption, Joy/Hulga's education--and her society's attitude toward that education--represent a common bias (pressure) many educated women faced (and still face).
Joy/Hulga's mother, Mrs. Hopewell, articulates the soft edge of this bias when she thinks that Joy/Hulga's expression is the only thing keeping her from looking pleasant:
Whenever she looked at Joy this way, she could not help but feel that it would have been better if the child had not taken the Ph.D. It had certainly not brought her out . . . and there was no more excuse for her to go to school again. . . it was nice for girls to go to school to have a good time. . . .
Mrs. Hopewell, like many people in the rural south in the mid-1950s, did not value education-for-education's-sake and, more important, could see no benefit of that education in Joy/Hulga's behavior or attitude. Her comment that the primary reason for a girl's education was "to have a good time" represents a widely-held belief that women, most of whom would under normal circumstances become wives and mothers, did not need more than a basic education. This view is, unfortunately, still held by a surprising number of people and is a constant impediment to women's struggles for equal rights and treatment in many spheres of life.
A few paragraphs later, Mrs. Hopewell articulates a problem that has become a pressure felt by generations of students seeking advanced degrees, especially in the humanities:
The girl had taken the Ph.D. in philosophy and this left Mrs. Hopewell at a complete loss. You could say, . . . "My daughter is a schoolteacher," or even, "My daughter is a chemical engineer." You could not say, "My daughter is a philosopher."
Echoing sentiments expressed by many people before and after, Mrs. Hopewell expresses her frustration that Joy/Hulga's education is, from her perspective, completely impractical. If one measures education by its potential economic value, there is not much to recommend an advanced degree in philosophy, and Hulga's circumstances--a weak heart and missing leg--makes her PhD completely useless in her mother's view. This perspective, however, is not unique to Mrs. Hopewell--many people throughout the country consider education to have economic, not necessarily intrinsic, value.
In the context of her education, then, Joy/Hulga faces pressures brought on not by her personality or physical problems but by society's attitude toward women and education--a bias that existed in the mid-1950s and exists today.