Questions of the Day and of the Fray number 2: Heron, David. 1911. Mental Defect, Mal-Nutrition, and the Teacher’s Appreciation of Intelligence. A Reply to Criticism of the Memoir on ‘The Influence of Defective Physique and Unfavourable Home Environment on the Intelligence of School Children’ (London: Dulau and Co.). 34 pp.
Summary
Mental Defect, Mal-Nutrition, and the Teacher’s Appreciation of Intelligence is the second publication in the Galton Eugenics Laboratory series, Questions of the Day and of the Fray. Authored by David Heron, D.Sc. (Galton Research Fellow under Professor Karl Pearson), this 1911 work serves as a reply to criticisms of the laboratory’s earlier memoir concerning the influence of defective physique and unfavourable home environment on the intelligence of school children.
The original memoir, based on data from over 8,700 London school children (L.C.C. data), concluded that home environment factors and defective physique were not the chief determining cause of intelligence differentiation. They were, at best, a “second order” contribution, and no environmental condition was found to produce an effect on mentality comparable to the known influence of heredity.
Heron primarily addresses Mr. G. Udny Yule’s severe condemnation of the memoir, particularly Yule’s claim that the teachers’ estimates of children’s intelligence (classified into five verbal categories like ‘brilliant’ or ‘very dull’) were “absolutely valueless”. Heron defends these estimates by presenting external data (from Aberdeen school children) demonstrating that the teacher’s appraisal of general intelligence is “highly correlated” with the student’s place in examination results, with correlations as high as +.70±.02 or +.99±.01.
Crucially, Heron dissects Yule’s reliance on the extensive but dated survey by Dr. Francis Warner (1888–1894). Heron argues that Warner’s methodology was fundamentally flawed, noting that Dr. Warner could only have spent an average of 3.4 minutes per child, making detailed examinations impossible. He shows that Warner’s results—which suggested high correlations between mental dullness and traits like small heads or palate defects—are contradicted by modern investigations using careful, quantitative measurements. Furthermore, Heron criticizes Yule for using the “coefficient of association,” which “grossly exaggerated” results from Warner’s deficient data. When calculated properly, the correlation between mental dullness and low nutrition in the only children Warner actually examined was very small, matching the Galton Memoir’s conclusion. Heron maintains that Yule failed to provide evidence showing that environment outweighs the influence of heredity.
Questions of the Day and of the Fray number 2
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