SECTIONAL TRANSACTIONS.—J. 545 
Dr. G. SetuH.—Some clinical aspects of stuttering (3.30). 
1. The incidence of stuttering among school children. The sex-difference 
in the percentage of stutterers. 
2. Accepted causative factors. The réle of heredity and imitation. 
3. Developmental history of the stutterer. Other neurotic manifesta- 
tions. The psycho-analytic theory of the disorder. 
4. The stuttering character. 
(Full Section Meeting.) 
Prof. E. C. Totman.—The learning of rats (4.15). 
Sunday, September 10. 
Visit to Besford Court Mental Deficiency Institution, near Worcester. 
Monday, September 11. 
JornT SEssIon with Section L (Educational Science, ¢.v.) on The predictive 
value of school examinations and psychological tests (10.0). 
AFTERNOON. 
Visit to Lowdham Grange Borstal Institution, Nottingham. 
Tuesday, September 12. 
Jomnt Discussion with Department A* (Mathematics) on The validity 
and value of methods of correlation (10.0) :— 
Prof. C. SPEARMAN, F.R.S.—The theory of two factors. 
Foundation pillars of the theory.—Correlations between test scores ; 
observation of regularities; allowances for sampling errors; deduced 
constitution of scores ; other deductions. 
Points on which objections have been raised——Correspondence of theory 
with observation ; uniqueness of the factors; necessary existence of the 
factors ; interpretation of the factors ; scientific significance of the theory. 
Dr. WILLIAM Brown. 
As an important example of the value of methods of correlation in psy- 
chology, one may mention the employment of the tetrad-criterion 
(112%34 — T13%¥2, = 0) to test for the presence of a central intellective 
factor (g). The results of an extensive research, by Dr. W. Stephenson and 
the present speaker, on a large and homogeneous sample of boys, using 
nineteen carefully selected and standardised mental tests, show a frequency- 
distribution of tetrad-differences in close agreement with a ‘ theoretical ’ 
distribution, such as may be expected from a random sample drawn from 
correlations actually due to one central factor, thus supporting Spearman’s 
theory of ‘g.2. The form of distribution approximates closely to a Type IIA 
Pearson curve. 
Dr. S. Dawson. 
