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A . ~ S y m p o s i u m

P S Y C H O P H A R M A K O L O G I E

P S Y C H O P H A R M A C O L O G I E

DRUGS AS R E S E A R C H TOOLS IN P S Y C H O L O G Y

Organisator: A. St~IMERFIELD (London, England) Pra'sident: R. W. RUSSELt. (Bloomington, Ind., USA)

Re]erenten: H. J. EYSENCK, W. NOWLIS, C~ KORNETSKY, HANNAI1 STEIlffBERG~ R. W. RUSSELL

DisklL~sion: D. BINDRA, A. SUMMERIT1ELD, H. D(JKER

DRUGS A N D T H E V A L I D A T I O N O F T Y P O L O G I C A L

HYP OTHESES

H. J. EYSENCK London (England)

Drug investigations have usually been undertaken from a pharmacolo- gical point of view, i.e. with the interest of the investigator centeri.'n;~ on the question: "What are the medical/behavioural/psychological effects of this particular drug?" Such investigations are, of course, necessary and desir- able, but they have in the past tended to fall foul of important psychological principles. Thus psychological effects are often assessed by one or two routine tests of reaction tLme, intelligence, motor movement , etc., and results are stated in general psychological terms as an increase or decrease in motor co-ordination, intelligence, concentration, etc. Such statements are inadmissible because of the complex and compound nature of the majority of tests used. As factor analysis has demonstrated repeatedly, psychological tests tend to measure several factors simultaneously, and furthermore the factoral position of tests tends to vary with the degree of practice and may even vary from individual to individual. Another criticism of this line of approach is that the interpretation is on common sense grounds rather than being related to psychological principles. Thus a decrement in pursuit rotor performance attributable to the action of a drug may indicate that the drug

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is lowering the drive level of the subject, that it is increasing his reactive inhibition, that it is decreasing his habit forming potential (sHn) or any combination of these three. Specific experiments designed to provide evidence regarding these various possibilities are required to make proper psychological interpretations possible. As an example of such work consider the decline in eyeblink conditioning produced by certain depressant drugs. If this is clue to a decrease in Hsa, then it would be expected that when drug and placebo groups are retested under placeb 9 conditions, after a 24 hour rest pause, the lower conditioning performance of the original drug group would be perpetuated. If the effect of the drug however is an reactive inhibition, then a reminiscence effect should bring the original drug group up to the level of the original placebo group during the second day's testing. We have found that results support the former hypothesis rather than the latter. Similar results based on similar reasoning, were obtained when decrement in performance on the pursuit rotor was made the subject o~ the investigation.

Along rather different lines lies another type of investigation relating drug effects to personality. Predictions here are mediated by two postulates. The first of these is a typological postulate, according to which extraverts are characterized by strong, rapid and long continued growth of reactive inhibition, while introverts are -characterized by the obverse; conversely, extraverts are weak in elaboration of excitatory potential, while introverts are strong in this respect. The drug postulate states that C.N.S. depressant drugs increase the growth of inhibitory and decrease the growth of excitatory potentials, while C.N.S. stimulant drugs have the opposite effect. (In all this the terms "excitation" and. "inhibition" should be understood in the sense of molar concepts in the system of learning theory described by Parley, Hull and others, rather than in any strict physiological sense. The terms extraversion and introversion are to be understood in the opera- tionally defined sense given to them in "Dimensions of Personality" and "The Dynamics of Anxiety and Hysteria".)

Drugs can readily be used to validate the different parts of this system because it may be deduced that tests which differentiate between extraverts and introverts, or between hysterics and dysthymics (two neurotic groups which are considered to represent the neurotic equivalent of extraverts and introverts), should be responsive to depressant and stimulant drugs, in the sense that stimulant drugs should shift perform.race on the tests in the direction typical of introverts, while depressant drugs should shift per- formance in the opposite direction. A considerable amount of work has been done in my department on the changes produced by stimulant and

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depressant drugs in relation to conditioning, nonsense syllable learning, pursuit rotor learning, reaction times, kinaesthetic figural after effects and visual after effects, apparent movement, flicker and flutter fusion thresholds, visual after image duration, rotating spiral after-effects, suppression of the primary visual stimulus, vigilance, meta-contrast, static ataxia, pupillary reaction to light, adapta~_ion, sedation thresholds and other phenomena; all of these are relevant to the concepts of excitation and inhibition along theoretical lines, and all have been studied in relation to personality. In the majority of cases predictions have been borne out in faet~ Thus, extraverts have been found to condition less well than introverts, hysterics and psychopaths less well than dysthymics, and sub}eels administered depressant drugs have been found to condition less well than subjects administered stimulant drugs. In a similar manner extraverts and hysterics have shorter visual after effects than introverts and dysthymics, with stimulant and depressant drugs having ~the predicted comparable effects.

Of particular interest are some of those cases where the predicted effect fails to appear. Thus, it was expected on the basis of the Leplcy-Hufl theory that the bowing of the serial learning curve would be more marked itx extraverts and hysterics than in introverts and dystbymics, and after the administration of depressant than after the administration of stimulant drugs. None of the predicted effects appeared, suggesting that possibly the Lepiey-Hull hypothesis was at fault. A separate experiment undertaken to test this hypothesis directly showed that experimental results were in fact incompatible with the maintenance of the Lepley-Hull theory, thus illus- trating that failures of prediction with respect to the typological and drug postulates might be due, not to errors in these postulates, but rhther to errors in the mediating hypotheses from the field of general psychology.

DRUGS AND THE EXPERIMENTAL ANALYSIS OF HIGHER

ORDER DISPOSITIONS

VINCENT NOWLIS Rochester, N.Y. (USA)

It has been suggested that some drugs modify the total reperloire of behavior available to the human subject in the testing situatiom Specific instances of this general hypothesis are found in the psychopharmaco- logical literature as assertions that certain drugs affect such global sta- tes as: sleep, trance, ecstasy, mood, empathy, social adjustment, tempe-