Drugs and Personality

Drugs and Personality

In the first paper of this series, it was pointed out that one of the reasons why McDougall's theory of drug action and personality was not accepted at all widely was connected with the fact that he failed to provide an objective, experimental test which could be used to diagnose extraversion-introversion, and to assess drug effects. This argument is not entirely correct; McDougall did in fact suggest one such test, namely the rate of fluctuation of so-called reversible perspective figures. Many varieties of these are known, and have been used experimentally; the Necker cube, the staircase, the vase-face, and the windmill patterns being probably the best known. In all of these, there is an ambiguity in the drawing which makes it possible to perceive two distinct patterns in the stimulus; on prolonged inspection these patterns alternate, and it is the rate of alternation, signalled verbally or by suitable mechanical arrangement, which constitutes the score on this test. It is known that different types of pattern give reasonably reliable scores, and also that rates of alternation on different patterns correlate quite highly together, thus demonstrating that one and the same tendency is being measured. That this tendency is of central rather than peripheral character is indicated by the fact that changes in the rate of reversal due to fatigue and other causes can be transferred from one eye to the other.

Drugs and Personality

In a previous paper in this series, a brief discussion has been given of the theoretical reasons for anticipating that depressant drugs would shorten the perceptual after-effects of visual stimuli, and stimulant drugs would lengthen these effects. The present paper is concerned with a related type of prediction, also concerned with certain visual after-effects. The phenomenon in question was first observed by Bidwell; it has not received much study, unfortunately, in spite of its great theoretical interest. The phenomenon is simply this. If a beam of red light (the primary stimulus, or Sp) is thrown into the eye of a person having normal colour vision, that person will report a red sensation, followed after the extinction of the light source by a series of after-images, usually in the complementary colour. The theory governing the appearance of the after-image is conventionally a photochemical one; the Sp produces certain effects in the retina which are opposite in direction for complementary colours and which are reversed when the Sp ceases to act on the retina. This reversal is perceived as the complementary after-image. Bidwell discovered that when the Sp is shown only for a relatively short period of time, say 20 milliseconds, and is immediately followed by a neutral stimulus, such as a beam of white light, then the S is not perceived at all, but only the complementary after-image. In other words, a red stimulus is perceived as green, a green stimulus as red. It is this perception of a non-existent stimulus which caused the phenomenon to be of such interest to psychologists.

The Effects of Meprobamate on Perception

A review of the history and experimental findings relating to the spiral after-effect can be found elsewhere (5) and will not be repeated here. The reliability of the after-effect, the major role played by the cortex in its production and the evidence already obtained that the after-effect is modifiable in accordance with Eysenck's drug action hypothesis (2) indicated it to be a promising test in the investigation into the effects of meprobamate on perception.

The Spiral After-Effect As a Test of Brain Damage

A number of studies have been recently concerned with the clinical application of the Archimedes spiral, an illusory negative after-effect of apparent movement, which requires no description here. Freeman and Josey (3) reported a relationship between the presence or absence of this after-effect and a clinical judgment of memory function, while a cross-validation study by Standlee (11) failed to confirm this observation when an objective measure of memory impairment was used.

Drugs and Personality

In a previous paper in this series Eysenck, Holland and Trouton (1957) showed that the seen after-effects resulting from stimulation by means of a rotating spiral were increased very little by a stimulant drug and decreased significantly by a depressant drug. At that time there was little evidence that these aftereffects were in fact correlated, as the theory demanded, with extraversion and introversion. Since then two separate experiments dealing with normal and neurotic subjects respectively produced very strong evidence in favour of this hypothesis (Eysenck, 1960), and it seemed desirable to repeat the experiment in order to discover whether the failure of the stimulant drug in the first experiment to produce very positive results was merely a chance effect or was in fact a genuine failure of the theory.

The effect of 1-arylcylohexylamine (sernyl) on twelve normal volunteers

The production of “model psychoses” in animals and man by a variety of chemical substances is of great interest. While the relationship between disturbances so produced and schizophrenia are problematical, these investigations may eventually throw light upon the causes of this condition. More important, at present, is the fact that the investigation of the way these drugs modify various aspects of normal psychological functioning is of great value in suggesting the physiological and biochemical processes that underlie these functions.

An increase in strength of tilt aftereffect associated with tryptophan depletion

The effects of a tryptophan-free amino acid mixture on tilt aftereffect, movement aftereffect, and the Mueller-Lyer illusion were studied. 12 male subjects ingested either a balanced amino acid mixture or a tryptophan-free mixture which causes a marked depletion of brain tryptophan and serotonin. The tryptophan-free mixture significantly increased the strength of tilt aftereffect but had no effect on movement aftereffect or the Mueller-Lyer illusion. These results were discussed with reference to the pharmacological activity of serotonin and its influence on the strength of lateral inhibition in mammalian brains.

Extent of spiral aftereffect as a determinant of spiral structural complexity

The absolute magnitude of expansion/contraction reported by 10 male and 10 female postgraduate students, one of the three response measures employed, discriminated most among 8 arithmetic spirals of 2 bandwidths. It decreased as the number of turns increased in a spiral.

Instruction effects and relation between extraversion and the spiral aftereffect

The relation between extraversion (EPI) and length of aftereffect was investigated when spiral aftereffect was measured on the same Ss under three instructions: (a) normal— S is told to report “When the aftereffect appears to stop” and after Ss had been informed of two phases in the decay of the aftereffect and told to (b) report the end of the first, faster, phase of decay, or (c) report when “they were absolutely sure that the second phase of decay had ended.” Near zero correlations were obtained between E and SAE under conditions (a) and (c) but E and SAE were negatively and significantly correlated under condition (b). It is suggested that failure to differentiate these instruction conditions could account for many of the previous contradictory findings on the relation between E and SAE duration.

Lack of effect of stimulant and depressant drugs on spiral aftereffect

Eysenck's claim that sodium amytal shortens and dexedrine lengthens the duration of spiral aftereffect was not borne out in any of four experiments designed to demonstrate it, including a replication of his study. A further replication, different only in the stimulus used, yielded no effect of amytal or dexedrine. Actual measurement of aftereffect rate immediately following the eliciting stimulus and after selected delays showed an exponential decay function for aftereffect rate but did not demonstrate any effect of the two drugs. This repeated failure to demonstrate a change in aftereffect as a result of the administration of drugs known to affect neuron firing thresholds has implications for the understanding of neurophysiology of visual motion perception. It was proposed that motion aftereffect is based on a comparison of the states of two neural systems both of which are equally affected by the drugs.

D-amphetamine and amytal. I. Effects on memory and expressive movement

“We would predict that any test which has been shown to differentiate reliably and validly between introverts and extraverts will, when applied to subjects who have been administered an excitant (or depressant) drug, show shifts in scores in the direction characteristic of greater introversion (or extraversion).” “… the effects of depressant drugs are similar to those of brain damage as far as objective psychological tests are concerned. Conversely, the effects of excitant drugs are opposite to those of brain damage.” These predictions by Eysenck (7) were tested using measures of immediate memory and expressive movement which had previously been validated against extraversion and brain damage. The measures discussed are derived from the Figure Reconstruction Test (immediate recall version).