Prrwm rnJ,I,d. 0,/r Vol 12. %I 2. pp 157-171. 1991 01914869 91 f3.M) to.00 Pnntcd ,n Great Bma~n. ,411 nghts merwd CopyrIght T 1991 Pcrgamon Press plc

GRAY’S BEHAVIORAL INHIBITION SYSTEM: A PSYCHOMETRIC EXAMINATION

CRAIG MACAXDREW* and TIA STEELE

School of Social Sciences. University of Cahfornia. Irvine. CA 92717. U.S.A.

(Rrceired 9 July I9901

Summary--Gray has posited a neurologtcally anchored emotion system--the behavioral inhibition system (BIS). He has further posited that lo stable individual differences in the sensitivity:reactivity of this system

there corresponds a major dimension of personality temperament-specifically a dimension of fearfulness-

fearlessness. i.e. of trait anxiety. Comparisons of the MMPI item-response rates of three samples of female putative normals and of purified samples of female psychiatric outpatients and prostitutes (which were

selected lo represent the extremes of fearfulness and fearlessness. respectively) resulted in the locatIon of 30 items that displayed the relationship: psychiatric outpatients > putative normals > prostitutes. The

psychometric properties of the scale comprised of these 30 items, irs relationship lo Eysenck’s scales of Neuroticism and Extraversion as well as to other scales. and the marked correspondence between the

manifest contents of its constitutive items and a set of experiential and behavioral expectations derived from the functions which have been attributed to the BIS combine to provide strong support for the cxtstcnce of a dimenston of personality temperament of the sort which Gray has proposed.

Gray (iY72, 1975, lYY7a. b, lY8X) has proporcd that within the mammalian brain there exist three scparablc but interacting systems for the control of emotional behavior, i.e. behavior which is

clicitcd by primary reinforcing cvcnts and by stimuli (secondary rcinforccrs) associated with such

cvcnts. Each of thcsc ‘emotion systems’ --the behavioral inhibition system (BIS), the behavioral

activation system (RAS), and the light -tlight system-is construed as rcsponsivc to a specific subset

of this total set of primary and secondary reinforcing cvcnts. Since persons are known to difrcr

markedly in their reactions to both primary and secondary reinforcing events, Gray has further

proposctl that a major dimension of pcrsonalityitcmpcramcnt may correspond to individual

dilrcrcnccs in the scnsitivity;rcactivity of each of these three emotion systems. In the case of the

BIS, this latter proposal has been dcvclopcd in some detail (Gray, 1970. 1976. 1981. 1982. 1985;

Gray, Owen. Davis Sc Tsaltas, 1983). Since the BlS is that emotion system which is activated by what Gray has termed “the adequate

stimuli for anxiety”, i.c. stimuli which signal the possibility of impending punishment or of impending frustrutive nonreward, novel stimuli, and innate fear-producing stimuli, he has termed

the corresponding dimension of personality/temperament, Anxiety. Thus, in answer to the

qucsrion, ‘Why are some people more susceptible than others to the development of such dysthymic

symptoms as anxiety attacks, phobias, obsessional thoughts. compulsive rituals, and neurotic depressions’!’ Gray has proposed the following: (I) Persons display consistent individual differences

in fearfulness. i.e. in trait anxiety; (2) One’s sensitivity-reactivity to ‘the adequate stimuli for

anxiety’ is positively associated with one’s Icvel of fearfulness, i.e. of trait anxiety; and (3) Other

things being equal, the likelihood that one will develop dysthymic symptoms is a function of one’s scnsitivity:rcactivity to such anxiogcnic stimuli. Thus. for Gray, the explanation for why persons

ditTcr in fearfulness. i.e. in trait anxiety, is at the same time the explanation for why, crrerisparihus.

they differ in their susceptibility to the development of dysthymic symptoms.

Now, if the possession of a chronically hyper-reactive BIS results in a heightened sensitivity to ‘the adequate stimuli for anxiety’ and to a consequent increase in the likelihood that neurotic symptoms of one sort or another will eventually arise, it is reasonable to presume that the possossion of a chronically hypo-reactive BIS will result in a marked insensitivity to such stimuli, i.e. a marked lack of anticipatory anxiety and a consequent deficiency in the area of passive avoidance learning. Since the primary psychopath is known to be specifically deficient in this mode

‘To whom all correspondence should be addressed.

I57

158 CRAIG .LIACASDREW and TIA STEELE

of learning (e.g. Hare. 1970, 1978), and since Cleckley (1976, p. 340) in his definitive clinical portrait, has characterized the primary psychopath as being ‘almost . . . incapable of anxiety’, it has been deduced that. ceteris paribus, the possession of a chronically hypo-reactive BIS will increase the likelihood that ‘symptoms’ of a primary psychopathic sort will arise (Claridge, 1985; Gray et al.. 1983; Trasler. 1978). The relevant psychophysiological data appear to support such a deduction. After summarizing this body of findings, Fowles (1980. p. 87) concluded that “it is

possible to relate the clinical features of psychopathy to the psychophysiological data with the single assumption that primary psychopaths have a deficient BIS”.

To recapitulate. it is Gray’s contention that to stable individual differences in the sensitivity/ reactivity of the BIS there corresponds a major dimension of personality/temperament, with highly fearful persons (including. among others. persons who manifest neurotic symptoms) located at the pole of hyper-reactivity, highly fearless persons [including. among others-‘though presumably as a minority’ (Gray et al.. 1983. p. 309) primary psychopaths] located at the pole of hypo-reactivity. and the vast majority of persons located somewhere between these two extremes.*

In a recent critique of Gray’s general formulation. Eysenck (1987) has argued that for all practical purposes Gray’s dimension of Anxiety is simply a replicate of his (Eysenck’s) dimension of Neuroticism. Thus. he wrote (1987, p. 491), “. . . anxiety, however measured, is close to neuroticism (perhaps at an angle of IO to I5 ‘), with a slight mixture of introversion”. Moreover, he continued. “Even that is only true as long as we adopt a ‘mental’ definition of anxiety, i.e. in terms of verbalizations of worries, fears, and depressive thoughts; when we use more bodily symptoms of anxiety, then there is a slight correlation with cxtravcrsion”.

Since one can readily dcrivc a set of relatively discrctc specifications of the behavioral, attitudinal, and cxpcricntial concomitants of hypcr- and hypo-reactivity in this emotion system from the functions which Gray has attributed to the BIS--indeed. Fowles (1984, 1987) has already provided a set of such indicators perhaps a criterion-groups strategy will allow us to determine whether ;I dimension of f~;~rfrllncss~‘fcarlcssncss of the sort which Gray has cnvisagcd can be located by the use of conventional psychometric proccdurcs. Specifically, then, given the sclcction of appropriate criterion samples and a large. reasonably hctcrogcneous pool of items, a positive judgment rcg:rrding the existence of such a climcnsion would require that the following be the case: (I) The application of ;I set of mechanical clccision rules to the item-response rates of samples of (a) putatively highly fearful Ss, (b) putatively normal Ss. and (c) putatively highly fearless S, will yield a subset of items, the responses to which will display the relationship: a > b > c. (2) The intcrcorrclations between these items will be of a sufficient magnitude to warrant the claim that they constitute a scale. i.e. to warrant adding scores over items and treating the sum as the measure of a unitary attribute. (3) The substantive content of the items that comprise this scale as well as the factors into uhich these items cluster will be in general accord with Fowles’ set of independently derived behavioral. attitudinal, and experiential indicators of the extremes of sensitivity/reactivity in this emotion system. (4) In cross-validation samples comprised of unselected runs of putative normals. this scale will be found to correlate substantially and positively with Eysenck’s Neuroticism Scale and substantially (but not as substantially) and negatively with Eysenck’s Extraversion Scale. The present paper presents an assessment of each of these expectations.

Because persons with dysthymic symptoms arc presumed to be high in trait anxiety, and because the presence of such symptoms causes many persons to enter psychotherapy, a run of female psychiatric outpatients was selected on a preliminary basis to represent the pole of extreme fe;rrfulncss and thus, ex hypothesi, of hyper-reactivity in the BIS. A sample of women with a documented history of having engaged in a specific form of socially proscribed behavior which, on common-sense grounds. vvould seem to entail little concern over placing oneself in potentially dangerous situations was selected, also on a preliminary basis. to represent the opposite pole of extreme fearlessness and thus, ex hypothesi, of hypo-reactivity in the BIS. An unselected run of

-~ .-I____ *Something of’ this sort had also been sugpcstcd. cn po.r.wtr. hy Clcckley (1976. pp. 257-258): “If the psychopath really

has :I ncuros~s. it is a ncuros~~ that IS manifested in a fundamentally different life-pattern from classic neurosis. mJn!fcstcd. one might say. in a pattern Ihat is not only ditfurcnt hur opposite” (our emphasis).

Gray’s Behavioral Inhibition System 159

Table I. Scores of onpmal and Ideal-ryptcal cnenon samples of female psychlarnc outpar~ents anJ prosr~turcs on 70 mawmally dwximlnatmg MMPI

Items

SCOR

n Kl”gc M=SD I

I50 15-62 42.41 2 I I 26 IS0 8-53 21.43 * Y 67

lb.JY*

50 JY-62 5J 22 f 3 55 50 R-16 I? I1 2 1.13

67..lh*

convicted female prostitutes-most of whom were either call girls or streetwalkers-comprised this

sample. Accordingly, and with the Minnesota Multiphasic Personality Inventory (MMPI) chosen to

provide the item pool, the MMPI answer sheets of the following approximately age-matched

criterion samples were assembled: (I) A sample of I50 young female psychiatric outpatients (mean

age = 23.68 +_ 4.44; range: 15-37) who were receiving treatment at the Neuropsychiatric Institute

of the University of California. Los Angeles. Except for an attempt to achieve approximate

age-comparability with the sample of prostitutes. this sample was otherwise unselected. (2) An

unselected run of I50 convicted female prostitutes (mean age = 23.70 + 3.75; ranpc: IS-37) who

had been referred by the local courts to a group-therapy program conducted by the Institute of

Law and Psychiatry of the University of California, Los Angeles.

The MMPI item response frequencies of these two samples were compared by 2’ and those items

that yielded a l’ value > 15.00 (a large, but arbitrary. magnitude) wcrc sclcctcd to comprise a

preliminary instrument with which to assess the homogcncity of each sample.* Scvcnty items wcrc

found to satisfy this criterion and. with item-scoring kcycd to the psychiatric patients’ dominant

rcsponsc. all 300 Ss were scored on thcsc 70 items. The avcragc scores +SDs of the two preliminary

criterion samples arc prcscntcd in Table I. Since the dilfcrcnccs bctwccn the means of thcsc two samples was found to be both Iargc and highly significant (mean dilrcrcncc = 19.98; ! = 16.49.

P < 0.001). it was evident that very substantial dilrcrenccs of some sort were at issue. Howcvcr.

it was equally clear from the size of the standard deviations and from the apprcciablc overlap of the two score distributions that ncithcr sample, as it stood, was at all homogeneous. But since thcrc

is no empirical basis for presuming cithcr that all female psychiatric outpatients will turn out to

bc dysthymics or that all prostitutes will bc found to fit the popular stcreotypc of the ‘happy hooker’, and since in both cases there is an abundance of cvidcncc to the contrary, such

intra-sample heterogcncity leas scarcely unexpected. In an ctTort to increase the homogeneity of each sample while at the same time maximizing the

dill-ercnce between them, the highest scoring one-third of the psychiatric outpatients (n = 50) and

the lo\vcst scoring one-third of the prostitutes (n = SO) wcrc selcctcd as ideal-typical rcprcsentativcs

of their respective samples and the remaining 100 members of each sample were eliminated from

all further consideration. The average scores f SDS of these two 50-member ideal-typical criterion

samples are also presented in Table I. Comparing the two sets of data, it will be observed that both standard deviations are now (of course) appreciably smaller and that the diffcrcnce between

the average scores of the ttvo refined samples has bccomc truly gargantuan: not only has the mean difTercncc more than doubled (from 19.98 to 41.05 points). the lowest scorer among the SO

ideal-typical psychiatric outpatients now outscores the highest scorer among the 50 ideal--typical

prostitutes by 33 points.? To summarize. WC began by assembling two samples-150 otherwise unselected psychiatric

outpatients and I50 otherwise unselected prostitutes-which, on common-sense grounds. we assumed would represent appreciable diffcrcnces in fearfulness. We then selected as the ---- ‘The testing format of the lnstitutc of Law and Psychiatry from which the sample of prostitutes W;LS obtained rcquircd

that clients answer only 429 of the MMPl‘s 550 different items. In consequence. the item pool used in the present study consists of 429 rather than 550 items.

tAlthough slightly younger. the two idcal-typical criterion samples retained the ape-comparability of the original samples: the aberape age of the 50 ideal-typical psychiatric outpatients was 23.0 k4.18. range: IX-35 and that of the 50 ideal-typIca prostitutes was 23. I k 3.84. range: I8 -36 (I = 0. I?. P > 0.05).

160 CRAIG MACASDREW and TIA STEELE

ideal-typical representatives of their respective samples those 50 psychiatric outpatients who least

resembled the 150 prostitutes, and those 50 prostitutes who least resembled the 150 psychiatric outpatients. To obviate any possible misunderstanding. we would emphasize that it is not our contention that we have thereby necessarily ended up with 50 classical dysthymics and with 50

Cleckly-style primary psychopaths. We cannot and do not make such a claim. Rather, our presumption is that if we were correct in supposing that the original criterion samples differed along a dimension of fearfulness-fearlessness (and thus, ex hypothesi, in the sensitivity/reactivity of the BPS). the purification of these samples (from 150 vs 150 to 50 vs 50) should have served to heighten this difference.

Because our concern was to locate items that displayed the relationship, ideal-typical psychiatric outpatients > normals > ideal-typical prostitutes. item response data from the following three samples of putative normals also entered into the item selection process: (I) A sample of 147 female undergraduate students (mean age = 70.0 + 3.34; range: 17-38) who were attending the University of California. Irvine at the time of testing (hereafter: California students). (2) A sample of 2369

female undergraduate students from the University of Minnesota (hereafter: Minnesota students). Item % ‘True’ and ‘?’ data for this sample. which was assembled by Loper, Robertson and Swanson (1968). are contained in Butcher and Pancheri (1976). (3) A sample of 1690 female medical outpatients between the ages of 20 and 29 who were receiving treatment of a non-psychiatric sort at the Mayo Clinic (hereafter: medical outpatients). Item % ‘True’ and “?’ data for this sample. which was assembled by Swenson. Pearson and Osborne. arc contained in Swenson, Pearson and Osborne ( 1973).

ITEM SELECTION

The item sclcction process procccdcd in two stages. In stage one. the MMPI item rcsponsc frcqucnciss of the two idcal -typical criterion samples (11 = 50 vs 50) wcrc compared by x2. Bccausc I61 items achicvcd a 1’ value > IO.83 (P <O.OOl). an arbitrary and far more stringent criterion

of x2 > 25.00 was adopted. Eighty-six items were found to satisfy cvcn this criterion and thcso 86 items bccamc the pool from which the final selection of items was made.

The second stage in the item-sclcction process required that an item satisfy all of the following additional criteria: (I) Idcaltypical psychiatric outpatients > California students both by x2 (P < 0.05) and in item response rate (difference > 10%); (2) California students > ideal -typical prostitutes both by x2 (P < 0.05) and in item response rate (difference > 10%); (3) Idcal-typical psychiatric outpatients > Minnesota students and medical outpatients (odds ratio > 2.0 and difference in item response rate > 10% for both comparisons);* (4) Minnesota students and medical outpatients > ideal-typical prostitutes (odds ratio > 2.0 and difference in item rcsponscs rate

> 10% for both comparisons). Of the 86 items that had satistied the criterion for stage one, 32 items also satisfied all of the

criteria for stage two. Having found that it is possible to locate a subset of items which display the desired relationship, ideal-typical psychiatric outpatients > putative normals > idcal-typical prostitutes, we turn now to an assessment of whether these 32 items are merely a random assemblage or whether they correlate with each other to a sufficient degree to warrant the claim that they measure a unitary attribute.

If the two ideal-typical criterion samples represent polar extremes on a major dimension of personality/temperament, then the 3, 7 items which we have located should display a marked

tendency to ‘hang together’. To assess this expectation, the MMPi answer sheets of a cross- validation sample comprised of an unselected run of 504 putatively normal female undergraduate students (mean age = 19.39 + 2.26) from the University of California, Irvine were assembled and coefficient z (Cronbach. 1951)-KR-90, in the present case-together with the corrected item-total correlations for each item were computed. For this cross-validation sample z was found to bc 0.84

*The odds ratio was adopted for criteria 3 and 4 because this statistic is unaffected by the appreciable differences in the sizes of the comparison samples.

Gmr‘s Behavioral Inhiblllon System 161

and 30 of the 32 corrected item-scale correlations were found to be significant at the P c 0.001 level. When the two items that failed to achieve this level of significance were eliminated and r was

again computed on the remaining 30 items. a value of 0.85 was obtained.*

To assess whether such results were specific to females. the MMPI answer sheets of a second

cross-validation sample comprised of an unselected run of 477 putatively normal male under-

graduate students (mean age = 19.89 i: 2.44) from the University of California, Irvine were assembled. An I of 0.81 was obtained for this sample and all 30 of the corrected item-scale

correlations were found to be statistically significant. _ ?9 of them at the P < 0.001 1evel.t Since these

are extremely high r values for an empirically derived scale constructed on the basis of a

criterion-groups strategy. it is concluded for males and females alike that these 30 items do ‘hand

together’ to a sufficient degree to lvarrant treating them as the constituent items of a scale.:

These 30 items (hereafter. the BIS scale). their psychiatric outpatient-keyed direction of response.

and their criteria-relevant l’ values and odds ratios are contained in Table 7. Since an extensively

revised version of the MMPI has recently appeared. it should be noted that all of these 30 items

have been retained in the new version of the instrument. Their listing in Table Z is accompanied

by both their original (MMPI-I) and their revised (hlMPI-2) identification numbers.

Table 3 contains the avcragc HIS scale scores of the five standardization samples and of the male

and fcmalc cross-valitfation samples of California students. It will bc ohservcd that the diffcrcncc

hctwccn the scores of the tlvo i&al typical criterion samplus is large and highly significant. It is

also cvidcnt that the mean score’; obtained by the st~liid~irtli/ation and cross-validation samples ot

putative norm;lls arc. in gcncral. both similar lo each other and apprcci:ibly diffcrcnt from both

of the idcal typic;il critcrivii saiuplcs.

tlowcvcr, ;llthough the nic;i~i HIS scale scores of the stantlarctiz~ition and cross-validation

samples of fcmalc Californi:l students wcrc virtually identical (I = 0. IX: P > 0.05). both of thcsc

v;~iucs wcrc significantly I;lrgcr (I’ < O.OOj anal I’ < 0.001. rcspcctivcly) than that obtained by the

malt truss-valida~iorl sample. To assess whcthcr this approximately two-point difrcrcncc in the

scores of putatively normal III;IICS and l~cmalcs is constant across the age-span, M MPI item rosponsc

data on the sample 01‘ psychiatrically normal medical outpatients from the Mayo Clinic which had

been asscmblcd by Swenson (‘I rrl. ( 1073) wcrc ag;lin consultcd.4 Although thcsc data were available

only in the form, I tcm ‘XI ‘True’ and “?‘, this sample was chosen both bccausc of its size 01 = 50.000)

and bccausc the available item rcsponsc data arc broken down both by sex (n = 35,723 females

and 14.277 malts) and by age for each of seven successive age-spans. Table 4 contains the avcrags

131s scale scores for each sex at each of these seven successive age-spans. The average difrerence

bctwccn the seven pairs of means was 2.02 points. Figure I contains a plot of these 14 values

together with the lcast squares line of best fit and the regression equation for each sex. It will be

observed that there is an orderly decline of approx. one-half point in average score as we progress

from one age-span to the next. That this inverse relationship between BIS scale score and age is

independent of sex is evidenced by the similarity of the two slope coefficients (F = 2.30; P > 0.05) and by the fact that the two standardized slope coefficients, i.e. the /I coefficients, were almost

identical (-0.984 for thr fcmalcs and -0.98 I for the males). Finally, although our concern in these

analyses has been descriptive rather than predictive, it is noteworthy that the coefficients of

determination were also found to be virtually identical for the two sexes (0.968 for the fcmalcs and

0.961 for the males).

--- *When the IWO ideal ,1)pical criterion samplrs wcrc comhincd with Ihe standardizu!lon sample of 147 Crtlifornia students.

x ~3s found IO be 0.91 for II = 32 i1ems and all 32 of the corrcc1cd Iwm-to131 correlalions were significant a[ P < 0.001. The corresponding I for 1hc 30 items US O.YO for 1hcse 247 SF.

tA furrhcr indication of 1hc comparability of the dala from 1hc male and female crowvalida1ion samples was alTordod by ;1 compariron of rhc two arrays of corrected item-scnlc corrclahons. The rank order correlation bctwecn thcsc IWO sets of 30 values H’IIS 0.87.

:Alrhough WC have no da1a on rhe long-term stability of person’s scores on this scale. 70 of 1he fcmalc studcnrs and 79 of the malt students had 1akcn 1he MMPI on two occwons. scpurated by an inrerval ofapprox. I I weeks. The 1eSt-rc1est rcliabillties Here quite robust for both sexes: r = 0.87 for the 70 females. and r = 0.86 for the 79 males.

*This is the larger sample from wluch our standardization sample of 1690 twenly IO 1wenly-nine year old remale medical oulpatienls ~‘3s obtained.

162 CRAIG S~ACASDREW and TIA STEELE

Table 2. Thu-ty items that dlffercntlate Ideal-typtcal neurotxs (I I from Cdhfomta students (2). ?vl~nncsoc;l students (3). medical patients (1).

and Idcol-typical prostitutes (5) and that d~ffcrcnttate samples 2. 3. and 4 from wmple 5

Item No. I: v3lues Odds r~ttos

M\IPI-I MMPI-I I \F 5 I \S? 2 \s 5 I us 3 I \s 4 3 vs 5 d vs 5

22 T 23T

52T

57F J9F 79F 63F

82T 70T

86T 73T

IO?T 89T

l42T I3OT

l63F l5:F

17OF I57F

I72T 16lT

I79T

19lT

2OIT

259T

27XT

282T

30JT

32IT

3:BT

352T

353F

I66T

178T

lR5T

233T

25IT

256T

275T

2Y9T

3IT

3:OT

321F

357T

MIT

37lF

3Y7T

4IIT

52OF

52IF

347T

452F

262F

544T Jh-IT I tccl tlrc:d .I aood dc.11 01 the ,,rnc. 50 YX w5x 4 !h 33 41 I’) 63 3.01 II I5

26.05

Jo.79

35.94

45.31

56.1’4

81.13

38 08

67 35

52 88

JO 7:

29 I6

3x 03

36 50 49 00

4x I5

40 YX

409x

41.11

50.93

59 69

J7 I6

29 35

4741

51 40

4x IX

44 26

43.07

33.57

2Y X6

IO 79

4, _), _ __

‘I 25

IO.13

36.79

33.06

12.40

3’.2l ._

36 76

I691

la 46

19.17

16.53

I3 a8

2x a5

lh.72

I:.‘)7

12.01

IY XI

56.94

39 20

Y 33

II 64

42 34

3 I 0‘)

IO 56

31 Y4

IO.22

Ii).YJ

9 03 5.52 5.42 2.88 2.93

3.36 IL’5 _ IO.01 2.98 3.65

a.05 Y.OI 5.78 2.27 3.54

33.16 77.79 36.99 2.40 5.04

l3W I.l la 7.85 12.25 22.12

30 20 3X.36 23 90 20.02 32.13

I9 2s 55 69 5J.J9 2.46 2.51

20 lb 12.82 14.06 Il.00 10.03

9 0: I6 32 4 20 3.14 12.23

I402 7 I7 7.66 6 89 6.45

5 30 6.04 5.23 2.0X 2.40

I2 x9 IO 25 7.68 13.50 1802

I I.95 5.52 3.82 5.50 7.96

23 87 R a4 9 02 4.27 4.18

IO OR 17.11 15.a7 2.20 2.37

I4 I2 S.V? a 3s 4.n.l 2.X6

IX 01 4.21 7.25 5.69 3.30

lY.55 IO.Y? 4 79 2.25 5. I3

I x 90 ‘I.72 7.60 4.52 5.78

7 76 IX.?? 17.62 IO.76 II.12

6 xl Y 5’) I J.0’) 4 25 2 KY

I? 42 3 Y3 .l 20 3.30 3.09

Y 117 x.44 7 x.1 4.64 5.00

5 21 ?.hO 5 25 2.60 5 25

Y 41 15.75 IO.42 2.40 3 63

IJ 00 IX.76 I5 31 2.01 2 46

x 5Y IO Yh I? ?I 5 22 4 60

15.02 7.00 4 YI 2.x7 4.0’~

II Y5 3 47 2 JO 6.77 lJ.55

Thcsc several analyses suggest that throughout the age-span the BIS scale scores of males can

be brought to approximate equivalence with those of comparably aged females either by adding

two points to each male’s score or by subtracting two points from each female’s score.

(I) I&AI typ~ul p\ychutrIc ourp.rt~nt\ (S) 50 2-l 36 = 2 71

(2) Fern& C‘~l~form;l student\ (S) 147 12.56 I b JO

(3) Fcm.tlc Cahfornu \tudcnt\ (CV) So4 Il.66 I 6. I3

(4) M~IC C~lll’ornl;l \lUlhll~ (CV) 477 10.x3 f 5 hO

(5) \~tnnc*or.l rtudcnts IS) 2369 IO 3X’

(6) Shxhc~l outp,,tc,nts IS) I690 I2 1.l.

(7) Ideal typicA prort~tutc\ (S) 50 J on f 2.6X

I \s 2: I = 12.64. P < 0.001 2 “1 4. , = 3 16,: P < 0 no5

I \%3. r-l266.P<0.001 2 vs 7: ,=90x: P <OOOl

I >% 4: , = I6 a5. P < 0.001 3 ,s 4: , = .l ax; P < 0.001

I Y1 7: I = 37.M. P < 0.001 3 VI 7. I =9x0; P <OOOl

2 ,5 3. I =o IX. P z-o.05 Jvs7:,=X.JI; P<OOOl

‘S~ncc the item responx data for ramplcr 5 and 6 were a\adable only m the form.

‘1, true’ utd ‘% 1’. only the me:m5 could be computed for thew IHO wmples.

Gray’s Behavioral inhibition System 163

Table 4. BIS scale wxcs of 25.723 male and 24.277 female medical out~ahents

FU%lkS M&s

Mean Mean A@ n BIS n BIS

16-19 695 I? 2.1 550 10.6R 20-29 I6YO I?.IJ I ?YX Y 76 XL.19 347.l II.73 2905 9.OY

7- 0 Femalcr. i - 10.83-0.48X

JO-JY 5&5Y

W6Y 70+

5955 7209

5XY 1471

II.13 IO.37

Y6l 9.26

537Y 7097

5315 I733

X.76 8 5’

7.93 7.59

AW

Fig. I. Plot of the average BIS scale scores of 50.000 male and female medical outpatients a1 each of seven age ranges.

Gray’s (1970) initial, essentially schematic, proposal for mapping his (assumedly orthogonal) dimensions of Anxiety and lmpulsivity onto the two-space constituted by the intersection of

Eyscnck’s orthogonal dimensions of Neuroticism (N) and Introversion-Extravcrsion (E) called for ~1 45’ orthogonal rotation of N and E. However, cvcn in that early article ho noted that some of

the then available data sccmcd to c:~ll for ;I rotation of ~45 :md subscqucnt findings Icd him (1982,

p. 453) to state more dcfinitivcly that “;I rotation which locatsd the resulting dimension of

“nnxicty” closer to Eyscnck’s N th;ln to his E would bc more appropriate”. It will bc recalled thut

Eyscnck, in contrast, has contended that Gray’s dimension of Anxiety is but a redundant version

of his (Eyscnck’s) N. albeit with ti slight admixture of Introversion.

If Gray’s dimension of Anxiety and Eysenck‘s dimension of Neuroticism do differ in potentially

conscquentiul ways, and if the BIS scale is :I mc;Lsure of Gray’s dimension, we would expect it to correlate substantially with both of Eysenck’s dimensions-substantially and positively with N, and substantially (but less substantially) and negatively with E. Contrariwise, if Eysenck is correct, we

would expect the BIS scale to correlate very substantially with N and only modestly with E. Since duta from the Eysenck Personality Questionnaire (EPQ) were available for the cross-validation

sample of 504 females and for 347 of the 477 members of the male cross-validation sample. the

relevant correlations were computed on these two samples. The correlation between the BIS scale and Eyscnck’s N W;IS found to be r = 0.74 (P < 0.001) for the females, and r = 0.69 (P c 0.001)

for the males. The corresponding correlation with Eysenck’s E wits found to be r = -0.45

(P c 0.001) for the females, and r = -0.41 (P < 0.001) for the males.*

Because Gray has suggested from time to time (e.g. 1982, p, 453) that Taylor’s (1953) MMPI- derived Manifest Anxiety Scale (MAS) might provide an appropriate measure of his dimension of

Anxiety, and because it has frequently been reported that both Scale 7 (‘Psychasthenia’) of the MMPI and Welsh’s (1956) MMPI-derived Anxiety (A) Scale tap very much the same variance as

does Taylor’s MAS. each of these three scales w;1s also correlated with Eysenck’s dimensions. The resulting correlation coefficients are contained in Table 5.

- l Rocklin and Revelle (1981) have presented a strong empirical case in support of the proposirion that the E scale of the

EPQ is not entirely comparable to the E scale of the EPI-the former being a rather pure measure of sociability, while the latter is a combination of soctability and impulsivity. Since the E scale from the EPI (Form B) had been administered to the female cross-validation sample and to 347 of the 477 members of the male cross-validation sample. this measure of E was also correlated with the BIS scale. The results for the two E scales were found to be almost identical: r = -0.40 (VS -0.45) for the females and r = -0.41 (vs -0.41) for the males.

CRAIG MACANDREW and TLA STEELE

Table 5. Correla~_~~s of rhc BIS Scale. Taylor‘s Mamfcst Anx~ery Scale (MIAS). rhe Psychasthema Scale (Scale 7). and Welsh’s Anxlcty Scale (A) wrh Eyscnck’r dlmensmns of Extravers~on (E). Neurornsm (X)

rnd Psyhouclsm (P) for cross-vahdrt~on samples of 504 fem.&s and 347 males

Corrclat~on wrh E>scnck‘s dlmcnsmns Irem E s P

n of 0WXlap ,wTlS wth BIS F M F ?.I F \f

BIS 30 -0.45 -0.41 0.71 0 69 0 -- l-) 0.14 !VlAS 50 9 -0 26 -0.22 0.83 0.82 0.33 0 10 Scale 7 4x IO -0.28 -0.24 0.7Y 0.79 0 34 0.26 A 39 6 -0 29 -0.25 0 x0 0.79 0.37 0 28

It will be observed that the male and the female data for MAS. Scale 7, and A exhibit an almost identical pattern of relationships with Eysenck’s dimensions of E and N. This is not surprising, however. for the magnitudes of the intercorrelations among these three scales indicate that they are truly three measures of ‘the same thing’. For the 504 females, the average of the three inter-scale

correlations was 0.91 (range: 0.884.93) and for the 347 males it was 0.90 (range: 0.SS-0.92). When we take the average of the three male and the three female correlations with Eysenck’s E and N Scales, we find a strong association with N (mean r = 0.80: range: 0.79-0.83). and an only moderate association with E (mean r = -0.26; range: -0. 22 to -0.29). When these average correlations with N and with E are expressed as a variance ratio. that ratio is 9.5: I, i.e. there are 9.5 parts of Neuroticism-associated variance to each part of Introversion-Extravcrsion-associated variance. Thus. Eysenck’s contention that Gray’s dimension of Anxiety is nothing but N ‘with a small mixture of introversion’ is clearly supported when scales such as MAS. Scale 7, and tl arc employed as ens’s mcasurc of Gray’s dimension. For the BIS scale, in contrast. the avcragc of the male and fcmalc correlations with Eyscnck’s N and E are 0.72 (vs 0.80; : = 3.93; P < 0.001) and -0.43 (vs -0.36; : = 3.99; P < 0.001) rcspcctivcly. Most tellingly. the variance ratio for the BIS scale is only 2.X--I (vs 9.5--l). i.c. thcrc arc only 2.8 parts (vs 9.5 parts) of Neuroticism variance to each part of lntrovcrsion--Extravcrsion-associated variance.

Having found that although the BIS scale is strongly associated with Eysenck’s Dimension of Neuroticism. it is not simply a duplicate measure of this dimension, we turn now to an assessment of whether its constituent items are in accord with a theory-derived delineation of the behavioral, attitudinal, and experiential indicators of a highly sensitive/reactive BIS. To aid in this assessment. the standardization samples of ideal-typical psychiatric outpatients and ideal-typical prostitutes wcrc combined with the standardization and cross-validation samples of California students, the item rcsponscs of these 50 + 50 + 147 + 504 + 477 = I228 Ss were intercorrelated, and the resulting 30 x 30 correlation matrix was subjected to a principal components analysis. The application of

Cattell’s (1966) scree criterion to the plot of the resulting eigenvalues called for a three-factor solution. Accordingly, a principal factors analysis (with R’s inserted in the diagonals) was performed, three factors were extracted, and these factors were rotated to oblique simple structure (oblimin solution). Examinations of the factor pattern structures obtained at varying degrees of obliqueness led to the judgment that a 6 of 0.6 was optimal. As was expected, given the scale’s high degree of internal consistency. the correlations among the three primary factors were found to be quite high: r,_? = 0.81, r,_3 = 0.78. and r:_) = 0.81.

The items that comprised Factor I depict a pervasive sense of inadequacy in the face of life’s demands.* This factor is defined by MMPI No. 328T (0.86); MMPI No. 544T (0.83); MMPI No. 41 IT (0.79); MMPI No. 3971(0.70); MMPI No. 3571(0.69); MMPI No. 259T (0.64); MMPI No. l63F (-0.54); MMPI No. l42T (0.52); MMPI No. 282T (0.46); MMPI No. 22T (0.44); and MMPI No. 352T (0.42). Although accompanied by expressions of excessive (MMPI No. 22) and either avowedly (MMPI No. 352) or presumably (MMPI No. 282) inappropriate affect, the conviction

‘For this and each of the following factors. only those items with factor loadings of 0.40 or greater are listed. The MIMPI-I item identification numbers are followed by the dominant ideal-typical psychiatric outpatient response (T or F) and. in parentheses. the item’s factor loading. II will be observed that. in every instance, a ‘True’ response is accompanied by a positive factor loading and a ‘False’ response is accompanied by a negative factor loading. This. of course. is as in should be.

Gray’s Behavioral Inhibition System 165

that one lacks the ability ‘to do’ (MMPI NOS. 142, 163, 259, 328,357, 397,411 and 544) constitutes the heart of Factor I. Following Bandura (e.g. 1977. 1982). we label this factor: Impoverished Sense of Self-Efficacy.

In Factor 2. this sense of inadequacy assumes a specifically social/interpersonal form. This factor is defined by MMPI No. 2OlT (80); MMPI No. 57F (-0.74); MMPI No. 304T (0.64); MMPI No. 521F (-0.56); MMPI No. 353F (-0.52); MMPI No. 520F (-0.49); MMPI No. 52T (49); and MMPI No. 172T (0.48). We label this factor: Social Reticence.

Factor 3 depicts a heightened vulnerability to the actions and the evaluations of others. It is defined by MMPI NO. 79F (-0.79); MMPI No. 170F (-0.53); MMPI No. 321T (0.46); and MMPI No. 36lT (0.44). We label this factor: Emotional Vulnerability.

As previously noted. Fowles (1984. 1987) has produced a vignette, based directly on the functions which Gray has attributed to the BIS, of what persons with a highly sensitive/reactive BIS would be expected to look like. Such persons. Fowles (1987. p. 422) says, “would be expected to exhibit shyness, social withdrawal. sensitivity to punishment and failure, a tendency to be easily discouraged, and a failure to develop active means of coping with situations”. We submit that

whether the items that comprise the present scale are viewed individually or in terms of the three factors into which they have been found to cluster, they are clearly in comport with Fowles’ set of BIS-derived indicators. Indeed, since theoretical discretion played no role whatsoever in the actual item-selection process, this correspondence is quite remarkable. As for the relationship which

Gray has hypothesized between primary psychopathy and the opposite pole of this dimension, the present data only entitle us to say than an abscncc of the sorts of sensitivities, concerns, and behavioral predilections which these items display would seem to constitute a necessary pre- condition for the cmcrgence of the indomitable self-assurance and general unflappability that Clccklcy and others have vicwcd as among the essential features of such ones.

The BIS scale scores of the malt and fcmalc cross-validation samples of California students were scparatcly corrclatcd with their scores on the following 26 scales: the 3 MMPI validity scales, the IO standard MMPI clinical scales, and Wiggins’ (1966) 13 MMPI-derived scales of manifest content. For each scale, the diffcrcncc between the male and female correlation was ncgligiblc. with none of the ditrcrcnccs reaching even the 0.01 level of significance. The virtual identity of this

pattern of relationships for malts and females indicates that if the BIS scale is tapping Gray’s dimension of Anxiety, it is doing so in a highly similar fashion for both scxcs.

In the cast of the MMPI’s 10 standard clinical scales, for both sexes the BIS scale correlated most strongly with Scale 7 (‘Psychasthenia’) which, as we have already seen (Table 5) is a good measure of Eysenck’s dimension of Neuroticism, and with Scale IO (‘Social Introversion’), which, for the present cross-validation samples, is substantially and negatively correlated with Eysenck’s dimension of Extraversion: r = -0.68 (P < 0.001) for the 504 females, and r = -0.64 (P < 0.001) for the 347 males on whom the EPQ was available.

As for Wiggins’ I3 MMPI-derived content scales, by far the strongest BIS scale correlations for both sexes were with the scales of ‘Poor Morale’, ‘Depression’, and ‘Social Maladjustment’. In independent factor analyses of the content scale scores of 250 normal males and of 250 normal females, Wiggins (1966) found in both analyses that these three scales were instrumental in defining a factor which he labeled ‘Anxiety Proneness vs Ego Resiliency’.* He characterized this factor as follows: the pole of anxiety proneness “suggests an individual lacking in self-confidence, who is socially inhibited and given to feelings of guilt and apprehensiveness. An individual at the (opposite pole) would be characterized by self-confidence and optimism; social ascendance and poise; and a confident, resilient approach to the future” (p. 27). Although we are not the first to report a positive self-characterization from a sample of prostitutes (see e.g. Exner, Wylie, Leura & Parrill. 1977) it still might be contended that the present, ideal-typical sample has come to be located at the ‘ego-resilient’ pole of this factor not because ‘they really belong there’, but because in taking the MMPI they engaged in a concerted effort to deceive, i.e. to ‘fake good’. If this were so, we

‘Jarnecke and Chambers (1977) also located this factor in the content scale scores of a sample of 242 male psychiatric inpatients.

166 CR\IG MACANDREW and TLA STEELE

must also credit them with being a quite sophisticated group of test-takers. for their scores on the MMPI’s three validity scales give no indication that they had been so motivated. When their average scores on these three scales (L = 5.0. F = 5.1 and K = 14.6) are plotted against the

instrument’s norms. all three values are found to be located near the mid-point of the normal range. Furthermore, as we shall see in the next section (Table 6). if their intention had been to ‘fake good’, they certainly did not act consistently upon this intention.

Ilems specific IO the criterion samples

It will not have gone unnoticed that the items which comprise the BIS scale fail to portray either the more severe clinical manifestations that we associate with the classical psychoneuroses or, in their denial, the more flagrantly antisocial behaviors and flawed moral sentiments that we have come to associate with primary psychopathy. Why is this so? Perhaps such items failed to appear on the scale because our two ideal-typical criterion samples-which, it will be recalled. had been selected on the basis of their presumed differences in fearfulnes-simply do not represent these two clinical categories. On the other hand, since the BIS scale was comprised exclusively of items that displayed the relationship, ideal-typical psychiatric outpatients > putative normals > ideal-typical

prostitutes, perhaps they failed to appear because the acceptance of such more flagrant self- characterizations were specific to those who have been selected to represent the extremes of fearfulness and fearlessness. We turn now to an examination of these two possibilities.

In order to locate items to which the ideal-typical prostitutes responded idiosyncratically, three criteria were applied to the item responses of the scale’s five original standardization samples: (I) ideal-typical prostitutes > California students and ideal-typical psychiatric outpatients (P < 0.005 by l’ for each comparison); (2) ideal-typical prostitutes > Minnesota students and medical outpatients (odds ratio > 2.5 for each comparison); and (3) idea-typical psychiatric outpatients = California students (P > 0.05 by 1’). Nine items were found to satisfy these criteria. These nine items arc listed in Table 6 together with their criterion-relevant x’ values and odds ratios, their correlations with the BIS scale scores of the male and female cross-validation samples,

and the x’ values obtained for each sex from a comparision of the item responses of those cross-validation Ss with the highest BlS scale scores (approx. 10%) vs those with the lowest BIS scale scores (approx. IO%).

In these nine items we encounter the indomitable self-confidence that had been implicit in the low BIS scale scores of the ideal-typical prostitutes now both explicitly stated (MMPI NO. 264) and accompanied by precisely the sorts of attitudes (MMPI No. 271). assessments (MMPI Nos. 141. 235 and 314). and behaviors (MMPI Nos. 56, I I8 and 294) that one would expect of primary psychopaths. Although the MMPI item pool, such that it is, could scarcely have produced a more compelling nine-item rendering of the essential features of primary psychopathy, we would not be justified in concluding on this account that our sample of ideal-typical prostitutes are primary psychopaths. Nor does our argument in any way require such a conclusion. (The tabled item-scale correlations and x’ values will be addressed at the conclusion of this section.)

Because the MMPI is heavily weighted with items that portray various of the signs and symptoms of the dysthymic disorders. many items were found to satisfy a set of ideal-typical psychiatric outpatient-specific criteria comparable to the criteria that had been used to locate the nine ideal-typical prostitute-specific items. Those nine items that maximally differentiated this sample from both the ideal-typical prostitutes and from the three standardization samples of putative normals are listed in Table 7 together with the l’ values, odds ratios, and correlations comparable to those contained in Table 6 for the nine ideal-typical prostitute-specific items. It will be observed that these nine items comprise a variegated assortment of the previously missing, more patently psychopathological sorts of self-characterizations that we would expect to find associated with the dysthymic disorders.

Since it is Gray’s position that the hyper-reactivity of a single emotion system-the BIS- conduces to the development of neurotic symptomatology, if the BIS scale measures one’s position on his corresponding dimension of Anxiety, we would expect that persons’ scores on this scale will correlate substantially and positively with their scores on the nine ideal-typical psychiatric outpatient-specific items which we have just identified. This correlation was computed for each of the cross validation samples and the results were as expected: r = 0.67 (P < 0.001) for the 504

Gray’s Behaworal InhIbition System 167

. . . . . . :::::::: _--- 4”““” ?p??? .39-T-

:“‘“rn~W~~g

, . . . . . . . . : : ::::::: ;F?,,qi?:q %$Z:s 5oddddddc

168 CRAIG MACANDIEW and TIA STEELE

females and r = 0.58 (P < 0.001) for the 477 males. Furthermore. the responses of Ss of both sexes to each of these nine items were significantly correlated with their scores on the BIS scale (P < 0.001

in all cases). Again for both sexes, when the item responses of Ss with high BIS scale scores were compared with the item responses of those with low BIS scale scores. all of the 18 comparisons were found to be statistically significant (P < 0.01 or greater in all cases). We conclude that for putative normals of both sexes the association between Ss’ BIS scale scores and their responses

to each of these nine, more patently psychopathological. items is both consistent and substantial. When we turn to the nine ideal-typical prostitute-specific items, the situation is more compli-

cated, for Gray has theorized that the general activity level in either of two emotion systems-hypo- reactivity in the BIS (which. ex hypothesi. conduces to the development of primary psychopathy) or hyper-reactivity in the BAS (which, ex hypothesi. conduces to the development of secondary psychopathyt_can increase the likelihood that one will engage in antisocial behavior of an ‘impulsive’ sort. Since. by Gray’s reckoning, we are here faced with a dual causal possibility. it would be expected that while the correlation between Ss’ BIS scale scores and their scores on the nine idea-typical prostitute-specific items will be significant and negative. the degree of association

will be less substantial than had been found to obtain for the nine ideal-typical psychiatric outpatient-specific items. This correlation was computed from each of the cross-validation samples and again the results were as expected: r = -0.36 (P < 0.001) for the 504 females and r = -0.32 (P < 0.001) for the 477 males.

However. when we examine the pattern of relationships between Ss’ RIS scale scores and their rcsponscs to each of these nine ideal-typical prostitute-specific items individually. everything falls apart. Thus. we find for both scxcs that four of the nine items, including the three patently ‘anti-social’ items (MMPI Item Nos 56. I IY and 294). display no relationship whatsocvcr to Ss’ HIS scale scores either for the total samples (as indcxcd by the item-scale correlations) or for those Ss of each sex who fall at the cxtrcmos of their rcspcctivc BIS scale score distributions (as indexed by the xL values). We also find for both sexes that the single ircm that expresses a callous indifTeronco to the travails ofothcrs (MMPI No. 271) isp~~.~irir.c~/~, rather than ncgati\cly. correlaled

with Ss’ BlS scale scores (P < 0.05 for each XX). Finally, when the three remaining items (MMPI Item Nos 141. _ ‘64 and 31-I) arc removed from the mordant context provided by thcsc either unrclatcd or negatively related items, they appear to constitute more an expression of autonomy

than of primary psychopathy. Nor can we attribute any of these findings to the fact that the BIS scale scores of the idcal-typical prostitutes were appreciably smaller than those of the lowest scoring approx. 10% of the male and female cross-validation samples, for such was not the case. Rather. the average BIS scale score of the ideal-typical prostitutes was higher than that of the lobvest HIS scale scorers of each sex (mean = 4.08 + 3.68 vs 2.79 F I. I2 for the 48 low scoring females. I = 3.13; P < 0.005; mean = 4.08 -+ 7.68 vs 2.08 f. 0.96; for the 38 low scoring males. t = 4.88. P < O.OOl).*

DISCUSSION

Gray (1988. p. 31) had defined his dimension of trait anxiety as a dimension of “individual dill’erences in susceptibility to the behavioral effects of anxiogenic stimuli”. One would suppose, then. that the relationship between the possession of such a susceptibilty and the frequency with which anxiety is experienced would be a direct one. Fowles (1982. 1984. 1987). however, has

suggested not only that this may not be so, but that the relationship may even be inverse. As his rationale in support of such a possibility relates specifically to the BIS, it runs as follows: since a person Lvith an extremely reactive BIS ivould be expected to develop an inhibited. risk-avoidant approach to the world. he would be expected to organize his life (insofar as it was within his power to do so) in such a way as to minimize his involvement in anxiety-provoking situations. Thus. insofar as anxiety is evoked by external factors, the anxiety-prone person may be able to rectify his otherwise fated predicament by judiciously selecting the ‘environments’ in which he engages himself. Completing the paradox, Fowles has further suggested that since a person with an

*EVUI when WC add IHO poinfs IO each of the male’s scores (to bring them to parity with the scores of females). the mean score of the low BIS males (51 = 2.08 + 1.00 = 4.08) still dots not exceed the mean score of the ideal-typical prost~tutrs (hl = 4.08).

Gray’s Behavioral Inhibition System 169

extremely unreactive BIS might be expected to engage in ‘risky’ behavior more often than others, he may turn out to experience anxiety far more frequently than does his anxiety-susceptible

opposite. But. while individual differences in passive avoidance constitute an important part of the story,

they are not the whole story. Given Gray’s (1988, p. 29) conception of the BIS as a comparator system whose chief function ‘is to monitor ongoing behavior, checking continuously that outcomes coincide with expectations’. there are two ways in which excessive activity in this system can give rise to the experience of anxiety. Anxiety may result when a ‘mismatch’ is detected and the system switches from its checking mode to its control mode of functioning: and it is this possibility-the possibility of reducing the frequency of such ‘mismatches’-that informs Fowles’ argument. However, anxiety may also arise as a consequence of excessive activity while the BIS is operating in its checking mode, e.g. “by tagging too many stimuli as ‘important’, searching for them too persistently, and so on” (Gray, 1988. p. 29).*

With this latter possibility in mind, let us examine our Ss’ responses to the item, “I feel anxiety about something or someone almost all of the time” (Table 6, MMPI Item No. 337)-an item which, at least in the typical case. would seem almost certainly to implicate an excess of checking. Since 44 of the 50 ideal-typical psychiatric outpatients (88%) answered this question in the affirmative, Fowles would have to hold that it was their inability to avoid anxiety-provoking situations that brought these 44 Ss to psychiatric treatment. While this may be the case, what of those presumably viable students (46 females and 41 males) whose BIS scale scores were in the highest 10% of their respective cross-validation samples? Since 58 of these 87 Ss (66.7%) also answered this item atlirmatively, one wonders if it is reasonable to presume that they, too, were the victims of incscapablc anxiety-provoking circumstances. Whatever one’s decision may be in this regard, it is instructive to note that of those 86 Ss (48 females and 38 males) whose BIS scale scores wcrc in the lowest IO% of their rcspcctivo cross-validation samples, only 3 Ss (3.5%) responded atiirmativcly to this item. Since the odds ratio for thcsc two proportions is 55.2. it would appear that although cxomplars of Fowlcs’ paradox are doubtless present in the general population, their prevalence is unlikely to bc sutliciont to warrant Fowlcs’ (1987, pp. 431-432) call for an uncoupling of ‘the bchaviorai corrclatcs of a dominant BIS’ from ‘a trait involving a dominance of anxious mood’.

If our data indicate that the relationship between the behavioral, attitudinal, and experiential indications of a highly sensitive/reactive BIS and the frequency with which one experiences anxiety is both direct and substantial, the same cannot be said of the relationship between a low score on the BIS scale and the presence of the more objectionable ‘signs’ of primary psychopathy (insofar as such signs arc cxcmplitied by the nine ideal-typical prostitute-specific items). Recall that when we examined the data from our putatively normal cross-validation samples (Table 6. above). only three of these nine items displayed a consistent negative relationship to Ss’ BIS scale scores. We want now to examine these three items for what they might tell us about the meaning of a hype-reactive BIS when it is encountered in samples of putative normals.

Since Trasler (1978. p. 273) has proposed that “the most conspicuous characteristics of the

psychopath relate to his insusceptibility to social influences”, we begin with MMPI Item No. 141. This item (which high BIS scorers of both sexes affirm and low BIS scorers deny) reads: ‘My conduct is largely controlled by the customs of those about me’. We submit that, in the absence of an accompanying history. e.g. of disciplinary problems at school (MMPI Item Nos 56 and 118) and of legal problems in the larger society (MMPI Item No. 294), only the most conventional of conventionalists would view a negative response to this item in and of itself as either prodromal or indexical of primary psychopathy. (Certainly, to press the point, one would not want to so label, e.g. those occasional Germans of recent memory who risked their lives by actively opposing the genocidal ‘customs’ of those who were then around them.) Nor, one would hope, does anything inherently ‘psychopathic’ reside either in the possession of robust self-confidence (MMPI Item No. 264) or in the fact that one’s ruminations engender neither shame nor guilt (MMPI Item No. 314). Finally, when we recall that Ss’ BIS scale scores are modestly, but significantly (P < 0.005 for both sexes) and positively, correlated with a lack of moral indignation where some show of indignation

*Compare the familiar folk observation that. “To a small child with a hammer. the whole world resembles a nail”

170 CRAIG MACANDREW and TIA STEELE

would seem to be in order (MMPI Item No. 271), we have strongprimafacie grounds for contesting Gray’s (1987a. p. 187) uncharacteristically incautious assertion that “a good case can be made for the supposition that individuals low in trait anxiety are those termed ‘primary psychopaths”‘. At the same time. nothing in the present set of findings conflicts with Gray’s more recent and more circumspect phrasing of this relationship: individuals who are low in trait anxiety, Gray (1988.

p. 32) says, “are predisposed toward primary psychopathy presumably because of their lack of fear”.

Buf if a high degree of fearlessness plays an important and indeed a necessary role in the emergence of the primary psychopath as Cleckley and others have long contended. it is also

constitutive of ‘the right stuff’ of such contemporary heroes as the original American astronauts (Wolfe. 1979). And while it may well be. as Lykken (1982, p. 22) has suggested. that “the right stuff is hard to handle and can easily become the wrong stuff”. the specifics of this alchemical process remain deeply mysterious. This much. however. is (or should be) clear: differences in moral development do not hinge exclusively on persons’ differing. constitutionally-fated propensities to experience anticipatory anxiety.

A final point: since we agree with Finney (1985) that the world has scant need for yet another ‘anxiety’ scale. our justification for introducing a scale. much (but not all) of whose variance is shared with the sundry existing anxiety scales. should be made explicit. Briefly, Gray (1988. p. 31) has argued that within the personality space assigned to the description of differences in emotional behavior, we should attempt to “locate our descriptive axes in such a manner that they are most likely to rctlect the activities of brain systems that control such behavior”. We find this argument compelling and conoludc that if the neural instantiation of the BlS is such a brain system-and Gray has asscmblcd a powerful cast in support of this possibility-the several analyses which we have rcportctl suggest that the prcscnt scale taps the dimension of pcrsonalityjtcmperamcnt which corresponds to this brain system.

But is the dilTcronce bctwccn Gray’s dimension of fearfulness-ft~lrlessness. i.e. of trait Anxiety, and Eyscnck’s dimension of emotional stability-instability. i.e. of Neuroticism, a dilfercnce that makes a ditrcrcncc? While the prcscnt array of tindings do not bear directly on this question, to the cxtont that they have succeeded in demonstrating that the BlS scale provides a measure of Gray’s dimension, its use in an cxpcrimcntal contsxt in conjunction with, and in comparison to, Eyscnck’s Neuroticism ScaIc would seem to provide a hitherto lacking rr~~~f~rs o~pcrcmfi by recourse

to which this question can bc empirically addrcsscd.*

.-II.k,run,k,c!~~,nrrnr., -WC wish to thank Dr Alexander Rosen of the Neuropsychiatric Institute. UCLA, and Drs John Suarcz and Aria Wallace of the lnstitutc of Lau and Psychiatry. UCLA. for access to Ihe MMPI answer sheets of thetr respective patients.

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*Should one have occasion IO USC the BIS scale as a means of S selection in an experimental context. the question might arise as to whether it is necessary to adminster the cornplc~e MMPI for this purpose. David Libert has collected data on 195 female and 76 male California students to whom the BIS scale was administered as an independent 30-item scale. (The order in which the items were presented was identical to the order in which they are listed in Table 2.) For neither sex were the resulting mean BIS scale scores significantly diffrrcnt from those of the cross-validation samples whose BIS scale scores had been obtained in the context of the complete MMPI: M = 12.66 t 6.13 vs 12.16 = 4.43; r = I.19 (P > 0.05) for 50-l vs I95 fcmalcs. and M = 10.83 + 5.60 vs 10.36 + 3.84; I = 0.92 (P > 0.05) for 477 vs 76 males.

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