LEFT-HANDEDNESS

New Zealand Herald, Volume LXIX, Issue 21252, 4 August 1932, Page 6

LEFT-HANDEDNESS

JEOFESSOR FITT EXPLAINS - POINTS MISUNDERSTOOD A COMPLEX SET OF DATA On the subject of left-handedness, p ro . fessor A. B. Fitt, of Auckland Universlt' College, writes:— Now that a fair number of people have through the use of the press colu mns ' had their little joke at my expense, is about time that the matter of this important problem was put right. At the outset, it must be made clear that m Uc h of the confusion is due to an incorrect report of the lecture and part of it t 0 insufficient knowledge of the implication of the facts and of the under which the investigations were conducted Most of the correspondents either were not at the lecture or did not understand its main points. It is very difficult to convey to anyone not highly trained in this field the pre . cise impression he should get from complex set of data. We greatly regret that through misunderstandings any hurt or unpleasantness should have been caused but this was not expected at the time of lecturing, for we could not know the extent of later misrepresentation. Series ol Tests Made The "left-handedness" referred to m the investigation is not just the simple fact of writing, say, with the left hand but was determined in the main by the application of a fairly complete series of tests. Most people .do not know without; such testing how many individuals are left-handed and in what degree. It chat be noted here, too, that the investigation) were all concerned with the different degrees of left-handedness and not just such a simple fact as that one :is merely right or left-handed. I can say without any hesitation that the headmaster of any school, if he should go to the trouble of testing for left-handedness, as the research group did, would find quite a different situation from the one indicated by a mere casual impression. The investigations reviewed in the leeture were concerned with seeing what relations (to be precise, "correlations") exist between hand-preference and intellectual and scholastic ability (determined almost entirely by the marks or the grading arrived at by teachers), psychopathic tendency, height and speed of tapping. They had nothing to do with such facts as skill in tennis, musical ability, ."intuitive gifts,' physical activity, physical weakness, judgment shown in sport, lefthanded billiard play, etc., which correspondents have persisted in talking about. Method Employed The method used in analysing these connections was the well-known statistical method of "correlation." A "coefficient of correlation" merely states the extent to which two factors vary in a similar or dissimilar way and says nothing about a causal connection. Unfortunately many people have erred in this latter point and believe u s to have said that because one is left-handed, therefore certain other facta will follow, such as poor mentality, etc. Now much of this error has been due to a faulty report of the lecture. In these columns on July 30 the Mowing ap-peared:—"Left-handedness expresses itself in some individuals in the form of poorer intellectual, ability, in others in the form of poorer physique and in others in a psychopathic tendency." The followlnS> which was read out verbatim at the lecture from a manuscript is the correct version:—"Such relatively low correlations as were found in* this study could bo explained if this general weakness, accompanied by left-handedness, -expressed itself in some individuals in the form of poorer intellectual ability, in others in the form of poorer physique, in others in a psychopathic tendency, etc., but not iu most or all forms in each case." The result of this serious distortion is to make one say something which one did not and could not- say, hence most of the mischief. Notice that the correct statement was made merely as a suggestion by way of giving a possible explanation for certain low, but persistent, correlations. Hence the terms "could be," "if," etc. " Ho Causal Relation " The wrong statement gives a definite causal relation between left-haudedness and several other factors, whereas the correct one gives no such causal relation between left-handedness and anything. It suggests a relation between "this general weakness" and certain factors. In the right context the phrase "accompanied by" means "if" or "when accompanied by." In fact, the whole is made quite clear by the previous sentence in the manuscript which reads: "It appears likely that lefthandedness accompanies some general inherited weakness which may manifest it' self in varying degrees in one or more directions of ability or function." How certain correspondents have got the idea that left-handed people are supposed to be either "unbalanced, physically weak or mentally feeble" ("A Distracted Mother"—August 3) or to have an "inferiority complex " (" The Kittagh August 3), I cannot discover, unless gleaned perhaps from the misleading columns of some other paper. Truly, this kind of joking is carrying the matter rather far. . Nofc one feeble-minded person was the subject of any part of the investigation. Bid we not find 4 per rent of left-handed-ness in the university, and 5.6 per cent in a secondary school ? Did we not find (a 3 reported in the lecture) some of the most brilliant people to be left-handed ? The whole matter has been grossly misunderstood. The whole study was concerned with the trends or tendencies noted wilh reference to certain relative differences'in thp fields of certain functions or factors. The scientific search tor tendencies has a certain significance which has nothing fo do with the problems and inference.' drawn by correspondents.