IV.—I ntelligence and A ge

S ummary . 141 graduates (72 men, 69 women) tested on a shortened version of Simplex Group Test in 1930–34 at average age 22 1/2 years, repeated the test in 1955 at average age 47, and scored 11.9 points of score higher on average on the later occasion. The improvement in test performance in the 24‐year interval is estimated to amount to about 0·7 or 0·8s̀ in terms of the standard deviation in the whole adult population. The improvement in performance was significant in all but one of fourteen sub‐tests, including both verbal and non‐verbal material. The correlation between scores on the two occasions of testing was +0·48. When corrected for homogeneity, this represents a test‐retest correlation of about +0·7. Part of the observed increase in score may have been due to (a) the difference in conditions of doing the two tests, and (b) general test sophistication; but the whole of it could not be thus explained away. In view of similar findings from five parallel American investigations, also with subjects of advanced education and superior ability, it is concluded that such persons do not give evidence of decline in test performance at least up to the later forties

Correlation · Sophistication · Cognitive Abilities and Testing · Mathematics · Psychology · Social Psychology

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