Variability of I.Q.S for Psychopaths Compared with Normal Children
- Author:
Verner Martin Sims
University of Alabama
The intelligence quotient as measured by jjresent day tests has never been assumed to be a constant factor, consequently, the variability of the I.Q. of psychopaths becomes meaningful only when interpreted in the light of evidence of the variability that exists with normal children. Ford, in his recent study “Variability of I.Q.s for Psychopaths Retested within Fifteen Days.” (Psychological Clinic, Nov.-Dec., 1929, Pp. 199-204) makes no such check on his findings, and as a result there is serious doubt as to the justifiability of certain of his conclusions. Having available data somewhat similar to those of Ford’s for a small group of normal children, and being familiar with a few studies reporting the variability of I.Q.s for other normal children when the interval between testings was brief, it seemed advisable to make a comparative study of the evidence on I.Q. variability for psychopathic cases when compared with normal children.
Ford’s study was based on forty-two eases, of which number thirty-six had 30 or more per cent of psychopathic function as determined by Mateer’s ‘’ Ten Points of Psychopathy.’’ In order that our results might be available for comparison with possible future studies it seemed desirable to limit this study to cases where an objective measure of psychopathic function was used. (Anyone interested will find, however, that the use of Ford’s entire group would neither make serious change in our findings nor alter the conclusions.) This group of thirty-six cases ranged in age from seven years and eight months to seventeen years and ten months (with a mean C.A. of fourteen years). The I.Q.s of the group ranged from 49 to 109 (with a mean I.Q. of 78) on the first test, and from 53 to 120 (with a mean I.Q. of 81) on the second test. They were all tested and retested within fifteen days with the Stanford-Binet scale. The average time between testing was approximately five and onehalf days.1 It is the purpose of this paper to compare the group of thirtysix psychopaths reported by Ford with certain groups of normal 1 These facts were either taken directly from the text of the article mentioned, or computed from data furnished in Tables I, II, and III. VARIABILITY OF I.Q.s. 27
children. Any significant differences may presumably be accounted for by the psychopathic conditions existing.
Most published work on the variability of the I.Q. has been based upon re-tests after a relatively long period of time; but two studies, supplemented with data which we have at hand, will perhaps serve our purpose. Terman and Cuneo2 report the re-testing after a period of forty-eight hours, with the Stanford-Binet Scale, of twenty-five children. The ages of the group ranged from three years and ten months to seven years and seven months (with a mean age of five years), and the I.Q.s ranged 011 the first test from 7G to 146 (with a mean I.Q. of 99) and on the second test from 85 to 144 (with a mean I.Q. of 104). These children came from representative social levels, were all American born, and presumably had no recognized psychopathic tendencies.3 They constitute one of the groups used here for comparative purposes.
The second group is reported by Lincoln.4 It consisted of thirty children from a small city school who were all between the ages of six and seven years. These children were tested in the morning and were re-tested the same afternoon by the same examiner with the Stanford-Binet Scale. The range of I.Q.s is not reported, but the author states that on the first test three children had I.Q.s of 110 or more and six had I.Q.s of 85 01* under.8 Lincoln reports no psychopathic tendencies as being observed.
The final group used in the comparisons reported later consisted of eighteen children enrolled in the training school attached to a small southern college. These children were all American born, and were of relatively superior social status. No psychopathic tendencies were observed. The children were tested with the StanfordBinet Scale, and exactly two weeks later were re-tested by the same examiner. Two examiners were used, one testing and retesting ten of the children, and the other eight.6
2 Cuneo, I. and Terman, L. M. < ‘ Stanford-Binet Tests of 112 Kindergarten Children and 77 Retests.” Pedagogical Seminary, Vol. 25., Pp. 41-1-428. * Ibid. P. 414. 4 Lincoln, E. C. “The Reliability of the Stanford-Binet Scale and the Constancy of the Intelligence Quotients.” Journal of Educational Psychology, Bee. 1927, Pp. G21-2G. ” Ibid, p. C24. ‘ These examiners, Miss Margaret Washburn and Miss Sallie Robinson, were teachers who did all the testing for the training school. Each had had defmito training under competent supervision, in the administration of the Stanford-Binet Scale, and had had extensive experience in its use. The members of the group were all between the ages of eight and nine years. The I.Q.s determined from the first testing ranged from 90 to 124 (with a mean of 108) and those determined from the sccond testing ranged from 92 to 136 (with a mean of 113). Since the results of this testing have not previously been reported, it is presented in Table I.
Table I SHOWING THE I.Q.s. FOR FIRST AND SECOND TESTING OF EIGHT YEAR OLDS C.A. (in months) I.Q. First Test I.Q. Second Test Change 100 124 136 12 99 123 134 11 96 120 131 11 104 115 112 ? 3 105 115 117 2 96 115 130 15 104 113 110 ? 3 104 108 109 1 107 108 117 9 101 105 106 1 104 105 107 2 102 103 110 7 107 101 99 ? 2 103 101 98 ? 3 100 101 108 7 98 100 96 ? 4 99 99 109 10 104 90 92 2
It will be noted from the above facts that the three normal groups are all younger than Ford’s group of psychopaths, that they have a higher average I.Q., and that the Terman-Cuneo group has a wider range of I.Q.s. For purposes of comparison it would be more satisfactory to have a group with approximately the same age and intelligence as Ford’s group, but since such a group was not available, these three are used. Such a comparison reveals some interesting facts. Table II reports the change in I.Q. for the psychopaths and for the normal groups. In this table no attention is paid to the direction of change, that is, whether there is an increase or a decrease on the second testing. Examination of this table shows that my own group had the greatest average change (although there was one case in Ford’s group that deviates more than any of my cases), with Ford’s group second, and the Terman-Cuneo and LinVARIABILITY OF I.Q.s. 29 Table II
SHOWING VARIABILITY OF I.Q.s. FOR FOUR GROUPS OF CHILDREN Lincoln Terman-Cuneo Ford Sims Psychopaths Interval between 3% to 4 lirs. 4S hrs. 5^/2 Days (Ave.) Two Weeks tests Change in I.Q. 1G to 20 points 1 11 to 15 points 1 ” 5 G to 10 points 5 8 ^ ^ 1 to 5 points 16 11 ^ 0 points 9 5 3 0 Total 30 25 36 18 Average Change .. . 2.6 4.2 5.2 5.8
coin groups next in order. It is interesting to note that this order is the same as the order of time interval between testings. In Table III the same comparison is made except that attention is paid to the direction of the change. It will be seen that twentyfive (or G9 per cent) of Ford’s group gained on the second testing and eight (or 22 per cent) lost on the second te.st; fourteen (or 56 per cent) of the Terman-Cuneo group gained and six (or 24 per cent) lost; fifteen (or 50 per cent) of the Lincoln group gained and six (or 20 per cent) lost; and thirteen (or 72 per cent) of my own group gained while five (or 28 per cent) lost on the second test.
TABLE III SHOWING DIRECTION OF CHANGE OF I.Q. FOR FOUR GROUPS OF CHILDREN Ford Interval between Lincoln Terman-Cuneo (Psychopatiis) Sims 31/. 4 hrs? 48 hrs? 51/i2 ‘layS 2 wlcS’ (average) Change in I.Q. 1G-20 points 1 11-15 points 1 ” ? G-10 points 5 10 3 o 12 5 1- 5 points 10 2 0 0- points 9 ? 5 5 ?1 to ? 5 points 6 3 ?G to ?10 points 05 36 18 Number of cases 30
These facts seem to indicate that when the interval between testing is short, a psychopathic condition has but slight influence so far as change of I.Q. is concerned. There is no decided difference between psychopaths and normals as to the amount of variation or the direction or variation noticed in these comparisons. We have no way of knowing what influence the differences in the age of the groups is exerting, or what the influence of the lower average I.Q. of Ford’s group is. It seems safe to say that the greater age of Ford’s group is not tending to lower the variability. In fact, what we know concerning the relation between reliability of intelligence tests and the age of the tested population would hint that it might be increasing the variability. On the other hand, there is some evidence furnished by the data indicating that the higher the I.Q. on the first testing, the greater will be the change on the reTABLE IV
SHOWING AVERAGE CHANGE FOR THE MORE INTELLIGENT AND LESS INTELLIGENT HALF Average change: Average change: Lower half Upper half Terman-Cuneo 2.3 5.5 Ford 4.7 5.8 Sims 4.2 7.7 testing. Lincoln’s I.Q.s not being reported, it was impossible to consider his data, but for the others, we have divided each group into halves on the basis of the size of the I.Q. and calculated the average change in I.Q. for the more intelligent and the less intelligent half. These differences between the upper and the lower half, presented in Table IV, seem to indicate a positive relationship between the size of the I.Q. and variability. The facts are not available to determine whether this would cause the psychopaths to show significant differences in variability when compared with normal children having the same I.Q.s and the same age.
Until further evidence is presented there seems no justification for, and actual harm may result from, drawing such conclusions as the following: “The theory of psychopathy is that the condition is one of unbalanced and unstable performance. The test variations seem better explained by this theory than by practice effect. Thus, the variable test performance is simply an objective factor, evidencing the general variability of the psychopath as theoretically deVARIABILITY OF I.Q.s. 31 scribed.”7 Or, as Ford states in another place, “The day to day variability is better explained by the theory of psychopathy as unbalance than by practice effect.”8 A literal translation of these statements would seem to mean that, for his group at least, the variability is caused by the unbalance. The comparisons presented here would tend to cause one to question such a conclusion. 7 Ford, C A. Psychological Clinic, Nov.-Dec., 1929, p. 203. 8 Ibid, p. 204.
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