Paul M. Hurst

Temporal relations between blood alcohol concentration and alcohol effect: an experiment with human subjects

Each of 40 fasting human subjects (20 men and 20 women) consumed 1 g ethanol (absolute) per kilogram body weight as a 20% solution by volume in organge juice. The time to peak BAC was found to be 24.0 min later than the time to peak alcohol effect as measured by magnitude estimation. This difference is both large and statistically reliable. These data are compared with those in the literature which usually show these events to be synchronous. Discussion includes reasons for this empirical discrepancy, implications of the theory of acute tolerance, and plans for future research.Examination of group data shows the same general trends obtained in the analysis of individual data: alcohol-effect scores reach peak earlier than BAC for the group as a whole (n=40), or for men alone, or for women alone. Moreover, alcohol-effect scores decline more rapidly in later trials than BAC scores, as has been reported earlier.

The effects of d-amphetamine on risk taking

SummaryThe effect of d-amphetamine on the risk-taking behavior of penitentiary inmates was investigated, utilizing a gambling situation involving cigarettes. The experimental situation consisted of choices between alternative gambles involving different amounts of risk. The 29 men served as their own controls, with the number of high-risk choices made by each subject when under drug (10 mg d-amphetamine sulfate, orally) being compared with the number of choices made during his placebo session. The difference was significant in the direction of increased risk-taking under the drug. The results are interpreted as offering tentative support to the hypothesis that d-amphetamine increases risk-taking, although alternative interpretations are provided.

The effects of amphetamines upon judgments and decisions

SummaryD-amphetamine sulfate, dl-amphetamine sulfate, and placebo were orally administered to 93 college student volunteers who served as their own controls in a Latin Square design. Dosages were adjusted to the two-thirds power of body weight with the proportionality constant set for 14 mg/70 kg with each drug. Effects were measured upon performances in a mathematical reasoning test, upon self-appraisals of these performances, and in a task which attached monetary payments to the accuracy of self-appraisals (“Decision Score”). The objectives of this research were (1) to reassess the biases in performance self-appraisals reported by Smith and Beecher (1964), and (2) to determine whether these biases represent mere verbal expansiveness or whether they are reflected by changes in decision behavior. Smith and Beechers effect upon self-appraisals was confirmed (at p<.02). Decision Score also was affected (at p<.01) in the predicted direction. Performance scores were not significantly affected.

DRUGS AND PLACEBOS: DRUG GUESSING BY NORMAL VOLUNTEERS

A series of 4 related experiments are described, using male and female student volunteers. Each experiment involved 3 to 5 evening sessions, during which a number of drug treatments were rotated among Ss. After drug ingestion, a series of experimental tasks, differing among the experiments, were used. At the end of each session, S reported on how the drug received had affected him, and classified the drug as a “stimulant,” “depressant,” “tranquilizer,” or as having “no effect.” In one experiment only the first two categories were used. Differences in drugs received accounted for only a small part of the variance in assigned categories. Amphetamines at the dose levels used were better discriminated from placebo than were other drugs. Limited (but recent) prior experience in being an S in drug experiments may facilitate drug recognition, if the experimental situation provides cues to S in relationship to task demands. However, since the over-all accuracy of drug recognition was only slightly better than chance (for both experienced and naive Ss), little error should be expected to arise from application of the usual (inert) placebo controls.

Effects of Alcohol and D-Amphetamine upon Mood and Volition

The purpose was to measure drug effects upon mood self-ratings and upon volitional outcomes presumably related to changes in mood. Alcohol, d-amphetamine and placebo were administered, separately and in combination, to 70 male volunteers who served as their own controls. Measures of volitional behavior included gambling for money, and verbal production on assigned topics. Mood self-ratings were interspersed. Alcohol increased the number of maximum bets but did not significantly increase average bet size or affect verbal production. D-amphetamine significantly increased verbal production but not risk-taking. There was no evidence of drug interaction in either of these measures of volitional behavior. However, there were interesting combinatorial effects upon the various mood dimensions, where the combination of alcohol and d-amphetamine produced additive, non-additive and supra-additive effects. As in some previous studies, drug effects on the mood self-ratings were found to be useful but uncertain predictors of plausibly relevant volitional behaviors.

The Effects of D-amphetamine and Chlordiazepoxide upon Strength and Estimated Strength

Four drug treatments were administered to each of 58 college student volunteers who served as their own controls in a Latin square design. The treatments wore d-amphetamine sulphate (11-17 nig), chlordiazepoxide HC1 (25 mg), placebo, and no drug. Grip strength was measured on a Stoclting hand dynamometer 3-3£ hours after ingestion. Prior to giving their maximum effort, subjects were required to estimate their strengths on the basis of perceived effort required to reach an assigned submaximum value, determined as a percentage of masked pre-test; scores. Objective strength was significantly higher under d-amphetamine than under any other treatment condition. The treatments did not differ significantly with respect to estimated strength or estimate bias. These results imply that the increase in objective strength was not mediated by suggestion.

REBOUND FROM D-AMPHETAMINE

This experiment involves measurement of direct and delayed effects on mood and performance of single doses of d-amphetamine sulfate. The purpose was to determine whether or not the drugs initial positive effect on some aspects of behavior is followed by a reversal or “rebound” below the placebo baseline even when sleep deprivation is controlled. 43 university students, recruited as paid volunteers, were given 10 mg/77 kg, 15 mg/77 kg, and a placebo (lactose) on three separate occasions in counterbalanced order under double-blind conditions. Behavioral measures and mood self-ratings were obtained on the day of drug ingestion and at intervals on the following day. Measures were selected from those previously established as sensitive to the initial, direct effects of amphetamine. Although strong initial effects were obtained on some of the measures used, subsequent rebound was either slight or nonexistent. Implications and limitations are discussed.

Some Dimensions of Affective Response to Drugs

This study is an attempt to dimensionalize the affective responses of normal humans to some common psychoactive drugs. To this end, the methods of factor analysis were applied to a drug X mood correlation matrix. This technique differs radically from previous applications of factor analysis to mood effects, in that the latter characteristically analyze a mood X subject matrix. Thus, instead of reflecting the organization of individual differences, the resulting factor structure represented a mood-dimension space in which drug effects were resolved as vectors. Amphetamines were found to produce strong effects along three mood dimensions, whose relative strengths depend upon dosage, latency, and a strong dosage X latency interaction. Susceptibility to independent manipulation by dosage-latency variations implies that the three dimensions constitute more than statistical abstractions and may represent isolable biochemical events.

Drug Effects upon Data Processing as Functions of Storage and Retrieval Parameters

A series of experiments was performed to investigate the effects of various stimulant and depressant drugs upon performance under task-induced stress. The first four experiments, each of which included d-amphetamine in one or more dosage, are summarized. This compound was generally the most facilitative of all the drugs tested, but in the fourth experiment reversed its enhancement effect. The fifth experiment, presented in detail, was performed to isolate the crucial task parameters which determine whether d-.amphetamine enhances performance or impairs it. To assess further the relationship between mood and performance effects, sodium amylobarbitono was also given, either alone or in combination with d-amphetamine. Results indicated that the enhancement reversal under amphetamine was specific to high input rates, rather than a function of difficulty per se or of other alternative mechanisms. Amylobarbitono given separately was closely comparable to placebo. When combined with rf-amphetamine, it yielded re...

Effects of Alcohol and Methylphenidate on Complex Judgments

Methylphenidate HCl (12 mg/70 kg and 20 mg/70 kg), ethyl alcohol (60 g/70 kg), and a placebo (lactose) were given to 50 college student volunteers. Each S received each treatment once during 4 separate sessions, and treatment order was counterbalanced. Ss were experienced bridge players, who were given sets of bidding problems, which varied in storage load, ambiguity level, and answer format (open-ended vs multiple choice). Performances were scored according to (1) frequency of active bids vs passes, and (2) a figure-of-merit assigned to each possible response, as developed from expert consensus. Ss wrote impromptu editorials on assigned topics from which word-count measures of verbal production were derived, and also made periodic self-ratings on mood adjective check lists. No significant drug effects were found on bidding accuracy, although methylphenidate increased the frequency of non-passes. Alcohol produced significant efforts on eight mood clusters while methylphenidate produced little or no measurable effect. Verbal production, however, was reliably increased by methylphenidate but not significantly affected by alcohol.