Eysenck – ‘aloof, dismissive’

In the March edition of The Psychologist Philip Corr ('The centenary of a maverick') made a welcome attempt to present the pros and cons of Hans Eysenck's substantial contribution to psychology. I wish he had gone a little further to try to account for Eysenck's over-confident foray into the vexed field of crime and personality. There he would have found that Eysenck (1964) attributed criminality to levels of extroversion and anxiety causing a failure in conditioning that in his opinion could be remedied by early childhood identification and the administration of appropriate drugs.

In drawing such a conclusion, Eysenck relied most on the array of Raymond Cattell's second-order 16PF factors that Frank Warburton (1965) (Professor of Experimental Education in Manchester University) had obtained from a sample of 38 adult males in the US Joliet prison (Eysenck, 1964, Table 4, p.194).

Because I happened to have a batch of similar 16PF data from a larger sample of New Zealand prisoners of each sex already to hand, I tried to validate Eysenck's important finding (Taylor, 1968), But to my surprise my data did not match Warburton's. Subsequently a colleague, Ronald Francis found a similar discrepancy with data from his sample of Australian adult male prisoners (Francis & Taylor, 1968).

In corresponding with Warburton, he became aware of having made a statistical blunder when appraising his data, and he promised to disclose it in his very next publication. Sadly he died shortly afterwards, and before being able to put the record straight. However, I sent copies of my dataset and correspondence with Warburton to Eysenck, and made arrangements to discuss the matter with him during my next sabbatical visit to London.

There I found the man aloof, dismissive, and not accepting the need to validate the evidence on which his bold assertions lay. So much, I thought, for the man who could not bear to admit he too had made a mistake in not checking his anchor, and was unwilling to correct the record for Warburton.

A.J.W. Taylor PhD, FBPsS
Emeritus Professor of Psychology
Victoria University of Wellington, New Zealand

References
Eysenck, H. (1964). Crime and personality. London: Routledge & Kegan Paul.
Francis, R.D. & Taylor, A.J.W. (1968). Extraversion and anxiety among certain groups of Australian offenders. Australia & New Zealand Journal of Criminology, 1(4), 249–251. 
Taylor, A.J.W. (1968). An examination of the personality factors of extraversion and anxiety in New Zealand's persistent offenders. Australia and New Zealand Journal of Criminology, 1(4), 243–248.
Warburton, F.W. (1965). Observations on a sample of psychopathic prisoners. Behaviour Research & Therapy, 3, 129–135.

The centennial year of the birth of Hans Eysenck should remind us of the vital role played by individual differences in personality, cognitive abilities and the like; as he stated in 1965: 'Individuals do differ…and it seems to me that psychology will never advance very far without a recognition of the complexities which are produced by this fact of personality.'

As highlighted in the title of his 1977 book Psychology Is About People, these individual differences are just as important as cognitive mechanisms and neural processes. To continue to ignore them does nothing to address one major reason for the non-replication of psychological effects. It is as if a research chemist were content to use pieces of laboratory equipment with scant regard to their varied and unknown electrochemical properties. As they would have failed to replicate the exact methodology, how likely is it that other experimental chemists would replicate their findings?

In psychology, individual characteristics affect behaviour in most situations – even purely experimental ones, where effect sizes tend to be small compared with the unexplained 'error' term, much of it concealing systematic individual differences which may be influencing experimental factors in varied and unknown ways. It is futile lamenting replication failures if we do not recognise the importance of the individual characteristics of participants in psychological studies.

We should take Eysenck's warning seriously: Psychology shall not advance very far if we continue to ignore this basic fact of human psychology.

Professor Philip Corr
City University London; President, International Society for the Study of Individual Differences; and Co-Founding President, British Society for the Psychology of Individual Differences