ABSTRACT
THE publication of the M.P.I. and various factorial studies connected with it aroused a certain amount of interest, and a number of critical discussions appeared, which raised fundamental problems obviously requiring an answer. Two of the main problems to appear were raised expressly by Carrigan (1960) in her excellent review of 'Extraversion/ Introversion as a Dimension of Personality'. The first problem to be raised by Carrigan was the relation between extraversion and adjustment ; her final comment was that 'A clear-cut answer cannot be given' (p. 351). It will be remembered that studies with the M.P.I. have usually shown a correlation of between 0·15 and 0·20 between neuroticism and introversion, with rather higher values for maladjusted sampies; this might be interpreted as showing a lack of orthogonality between the two factors. An alternative explanation of course would be that this correlation is an artefact produced by a faulty selection of items. It is clearly impossible to find items having loadings only on one or the other of the two type factors with which we are concerned; in the ordinary way each item will have at least some slight loading on the factor which it is not supposed to be measuring. If now in the selection of items there is a lack of balance in the positive and negative loadings on the factor which is not supposed to be measured by a givenitem, then an artificial positive or negative correlation between extraversion and neuroticism can easily appear. The possibility exists that in the M.P.I. there are too many items from the dysthymic quadrant, i.e. having 1 The results reported in this chapter, and their discussion, are reproduced, with permission, from Eysenck and Eysenck, 1963.
