Vito Perrone Sr., a leading advocate for humanistic, regimentation-free public education and a mentor to several generations of liberal reformers who fought the tide of standardized testing, died on Aug. 24 in Cambridge, Mass. He was 78.

The cause was congestive heart failure, said his son Sean.

Among progressive reformers, Dr. Perrone’s commitment to flexible teaching methods and his opposition to standardized tests made him the conscience of the profession in the modern era, when financially stressed schools nationwide embraced standardized tests as a way to improve academic performance and streamline the teaching process.

In Dr. Perrone’s view, which he disseminated for 40 years as a professor of education, first at the University of North Dakota and later at Harvard, the excessive use of such tests warped the education process, inhibited children’s natural interest in learning, caused teachers stress and prevented them from carrying out their real jobs: instilling in children a love of learning and teaching them the principles of citizenship in a democracy.

Though that view has been out of fashion in the mainstream of public education since the 1980s, Dr. Perrone’s persuasiveness attracted a stream of followers and helped give rise to a loose network of public alternative schools in New York, Boston, Chicago and Philadelphia.