BRAIN DIMENSIONS AND INTELLIGENCE.

Dominion, Volume 6, Issue 1629, 21 December 1912, Page 21

BRAIN DIMENSIONS AND INTELLIGENCE.

COMMONWEALTH STATISTICIAN'S OBSERVATIONS. The Commonwealth Statistician (Mr. G. H. Kiiibbs) has stated, in regard to the question of brain dimensions and intelligence, that much popular misunderstanding exists in regard to what is meant when it is said that the size Of the brain is possibly correlated with degree of intelligence. Mr. Knibbs mentions that Dr. Raymond Pearl's investigation published in "Biometrika," eomo few years ago, led him to believe that thore was no evidence that brain weight is sensibly correlated with intellectual ability. Dr. Pearl's investigation embraced 2100 adult male and 1034 adult femalo brains, representing Swedish, Hessian, Bavarian, Bohemian, and English sub-races, and the limits of the correlation were 'shown to. Tango between nought and six-tenths, nought denoting that there is absolutely no correlation, and unity denoting that it is completely established. Dr. Gladstone showed that in Certain cases the size of the brain cannot be gauged by the size of the head. His paper also is published in "Biomctrika." In order to avoid erros arising from the very variable, thickness of the skull, shot, mustard seed, rape seed, and silver sand have been used to measure the internal capacity of skulls. Even if tho correlation were established—that is, if, other things being equal, size indicated intellectual ability—we siiill would be able to decido in individual Oases which brain was the moro intelligent from the skull capacity. Thus, to take a case recently referred to,- if thero are tiro brains, one with a oapacity of 1471 cubic centimetres, and another 1491 cubic centimetres, it does not follow that tho latter belonged to a "slightly more intelligent person." Tho limitation of nil correlations is that they' cannot be applied to tho individual oaso. , They aro group relationships, and are true only of groups. It is only when tho groups of heads examined are st> largo that for each size there are brains of all varieties (of qualities associated with intelligence, whatever these qualities may be), that we can deduce the correlation depending on size accurately. If assured, however, that two groups of brains are fair samples, that is, have nil varieties among them, then the correlation of brain size and intelligence, even if established, only mean<>that tho aggregate of intelligence will bo found for tho group, where the brains are larger. External measurements ay>> very dubious, because the internal form a»<! external aro not in agreement, nor is tho skullthickness constant. It may bo said, concluded Mr. Knibbs, that Professor Karl Pearson and ])r. Alice T.oc pointed out r.s early n* 1!)02 Hint "there is lio marked correlalien br--1 ween ability and Hie shape or size of tlm hwid," and thin njrr<v>s willi conclusions of workers in Continental Eurow. .