Higher levels of ego development have been related to increasing levels of responsibility, tolerance, and achievement via independence, resiliency and interpersonal integrity. For example, in Loevinger's (1976) scheme of development one of the lowest stages of development is called "symbiotic," while the two highest stages are called "autonomous" and "integrated." Symbiotic is the antithesis of self-sufficiency, a trait of psychological maturity. A child lives in absolute dependence on its mother (or primary care giver) and its surroundings. Self sufficiency or independence develops gradually as the child passes through different levels of assuming responsibility and independence.