To summarize briefly: Converging data from many disciplines — psychology, psychiatry, social theory, biochemistry, neuropharmacology, neurophysiology — point to the sensory input regulating mechanism of the central nervous system as a critical factor in the production of hallucinoses and psychotic experience. There is good evidence that what we have called the informational underload model ‘holds considerable promise for improving our understanding of many clinical and non-clinical phenomena of interest to psychiatry. The evidence suggests that a neurophysiological, internal informational underload syndrome may be a final common pathway of psychotic experience. The question as to where such a syndrome might occur in the brain, together with the question of whether such an informational underload syndrome might be due to toxins, genetic factors, conditioning processes, anxiety or dissociation, or other causes, has to be left open. What is needed now, is research directed at these two questions: 1) does such an internal informational underload syndrome occur in the brain, 2) when, where, and under what circumstances does it occur?
: THE COMMISSION'S EXPERIMENTAL STUDIES OF ACUTE EFFECTS OF MARIJUANA, A 9 THC AND ALCOHOL IN HUMANSSubjects in the four projects were healthy young adult cannabis users. (primarily males). In all experiments, cannabis was administered in cigarettes under standarized smoking conditions which maximized THC delivery and absorption. The first study compared the effects of high purity synthetic /~ THC (on alfalfa) and natural marijuana on a battery of subjective, bchavioural and physiological measures. Three doses (9, 21 and 88 meg /~9 THC/kg) of each material were given. No significant qualitative or quantitative differences were found between equivalent doses of marijuana and synthetic THC. The lowest dose elicited a minimal reaction; the highest dose generally produced subjective effects slightly greater than those normally sough t by the subjects. Major effects (of both forms of cannabis) were: increases in conjunctival congestion, pulse rate, visual imagery, autokinetic movement, estimated passage of time, and subjective effect ratings; and reductions in salivation, skin temperature, and short-term memory.A second project examined the effects of the upper two marijuana doses and a single dose of alcohol (0.07% b.a.l.) on a limited range of automobile driving tasks. Both the alcohol and the highest marijuana dose produced a decrement in car handling performance. In addition, marijuana reduced driving speed and alcohol increased "rough handling" scores.A third project investigated some other psychomotor effects of the same two doses of marijuana, two doses of alcohol (0.03% and 0.07% b.a.L) and the low doses of both drugs combined. Both alcohol doses, the higher cannabis dose and the combined condition resulted in a decrement in compensatory tracking. Alcohol (but not marijuana) reduced response speed on several measures. Certain effects common to alcohol and marijuana were enhanced when the two drugs were given together.A fourth study explored the effects of a single dose of marijuana (66 meg A 9 THC/kg) on visual signal detection and, secondarily, the recovery of dim-light visual acuity after bright light glare. Marijuana reduced the accuracy of signal detection-probably by disrupting attentional processes. No significant effect on glare recovery time was found.
The grid test for schizophrenic thought disorder was administered to a sample of 149 psychiatric patients. This sample was drawn from a population with a known base rate of schizophrenia and an estimated base rate of thought disorder, thus allowing for the calculation of population specific cutting scores for the grid test.for diagnostic efficiency using conditional probability formulae. a diagnostic instrument.The grid test, using these data along with others from previous grid test studies, was then analysedThe conclusion reached is that the grid test for schizophrenic thought disorder is unsatisfactory asBannister & Fransella reported the development of the grid test for schizophrenic thought disorder (GT) in 1966 and published it in standardized form in 1967. The GT yields two scores: intensity (I) and consistency (C). Bannister & Fransella found, in setting cut-off points a t I < 1000 and C < +0.49, that 80 per cent of thought-disordered schizophrenics (TDS) and only 6.4 per cent of non-TDS, other psychiatric patients and normals in their sample scored below these points. Ninety point seven per cent of the subjects in their sample were correctly classified by the GT a s either T D S o r other than TDS.contexts. A cursory review of the literature from 1966 through 1978 indicates that at least 31 papers o n the topic of the GT have been published. Five of these papers, though not all specifically designed as replication studies, report data in a form suitable for comparison to Bannister & Fransella's (1966) original report. The findings of these studies are summarized in Table 1 . As is obvious from the summary, no one t o date, including the GT authors, has been able t o replicate either the valid and false positive rates o r the overall correct classification rate reported in the original GT study.Following its publication, investigators went on t o study the GT in a variety of
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