Actual Blood Alcohol Concentration Research Articles

Perception of intoxication in a field study of the night-time economy: Blood alcohol concentration, patron characteristics, and event-level predictors

ObjectiveDetermine the relationship of subjective intoxication to blood alcohol concentration (BAC) and examine whether patron and event-level characteristics modify the relationship of BAC to subjective intoxication. MethodsAn in-situ systematic random sample of alcohol consumers attending night-time entertainment districts between 10pm and 3am on Friday and Saturday nights in five Australian cities completed a brief interview (n=4628). Participants reported age, sex, and pre-drinking, energy drink, tobacco, illicit stimulant and other illicit drug use that night, and their subjective intoxication and BAC were assessed. ResultsMale and female drinkers displayed equally low sensitivity to the impact of alcohol consumption when self-assessing their intoxication (BAC only explained 19% of variance). The marginal effect of BAC was not constant. At low BAC, participants were somewhat sensitive to increases in alcohol consumption, but at higher BAC levels that modest sensitivity dissipated (actual BAC had less impact on self-assessed intoxication). The slope ultimately leveled out to be non-responsive to additional alcohol intake. Staying out late, pre-drinking, and being young introduced biases resulting in higher self-assessed intoxication regardless of actual BAC. Further, both energy drinks and stimulant use modified the association between BAC and perceived intoxication, resulting in more compressed changes in self-assessment as BAC varies up or down, indicating less ability to perceive differences in BAC level. ConclusionsThe ability of intoxicated patrons to detect further intoxication is impaired. Co-consumption of energy drinks and/or stimulant drugs is associated with impaired intoxication judgment, creating an additional challenge for the responsible service and consumption of alcohol.

Are you okay to drive? Commuting behavior and blood alcohol concentrations among restaurant diners

ABSTRACTObjective: Drink driving is widely recognized as a major road safety problem. In Australia, health promotion messages encourage monitoring the number of standard drinks consumed prior to driving. This pilot research aimed to investigate commuting behavior and blood alcohol concentration (BAC) of diners, including intended drivers, at Sunshine Coast restaurants.Methods: Five hundred and forty-four diners (n = 260 males) consented to participate in a brief interview and to use a breathalyzer device to measure their BAC.Results: Forty percent of participants advised they don't drink and drive (34% of males, 45% of females; 67.25% of <17–20 years, 30.5% of 50–59 years), and of the remaining participants, 75% advised they count the number of their drinks (69% of males, 84% of females; 32% of <17–20 years, 82% of 50–59 years), while 10% of participants monitored their BAC by how they were feeling (12% of males, 6% of females). Thirty-seven percent of participants said it was easy/very easy to estimate their BAC (41% of males; 33% of females; 21% of <17–20 years, 43% of 50–59 years). The actual BAC was less than expected for 56% of participants, with one-third underestimating BAC and some intended drivers having an actual BAC in excess of the 0.05 limit.Conclusions: Given the proportion of diners who reported they count the number of drinks, or use feelings as a way to gauge BAC, coupled with the considerable proportion who underestimated their BAC, a safer public health message is to avoid driving if you intend to drink. In addition, targeted intervention for experienced drivers (and, arguably, drinkers) appears warranted, as every participant aged less than 21 years who stated he or she would drive home indeed had a zero BAC. Interestingly every female driver who stated she would be driving home also had a legal BAC, suggesting gender-specific intervention.

Drivers who self-estimate lower blood alcohol concentrations are riskier drivers after drinking.

Alcohol increases the tendency for risky driving in some individuals but not others. Little is known about the factors underlying this individual difference. Studies find that those who underestimate their blood alcohol concentration (BAC) following a dose of alcohol tend to be more impulsive and report greater willingness to drive after drinking than those who estimate their BACs to be greater than their actual BAC. BAC underestimation could contribute to risky driving behavior following alcohol as such drivers might perceive little impairment in their driving ability and thus no need for caution. This study was designed to test the relationship between drivers' BAC estimations following a dose of alcohol or a placebo and the degree of risky driving they displayed during a simulated driving test. Forty adult drivers performed a simulated driving test and estimated their blood alcohol concentration after receiving a dose of alcohol (0.65 g/kg for men and 0.56 g/kg for women) or a placebo. Alcohol increased risk-taking and impaired driving skill. Those who estimated their BAC to be lower were the riskiest drivers following both alcohol and placebo. The tendency to estimate lower BACs could support a series of high-risk decisions, regardless of one's actual BAC. This could include the decision to drive after drinking.

Differences between the measured blood ethanol concentration and the estimated concentration by Widmark's equation in elderly persons

BackgroundThe Widmark's equation (C [BAC]=A/p×r) is the most commonly used formula in legal medicine to estimate the blood alcohol concentration (BAC) from the amount of ingested ethanol and vice versa. Within a drinking experiment with a target BAC of 1.2g/kg, a 75-year-old participant reached a maximum BAC of 1.83g/kg and showed signs of severe ethanol intoxication, while the other nine subjects (age: 19–31 years) had BACs close to the target BAC. This incident brought up the question, if the Widmark's equation is an appropriate tool for aged persons. MethodsA drinking experiment with 50 elderly voluntary test persons (22 males, 28 females, mean age and range [males]: 69.7 years, 60–84 years, mean age and range [females]: 68.5 years, 61–78 years) was performed. The amount of ethanol leading to a BAC of 0.6g/kg was estimated individually using the Widmark's equation (used Widmark factors: 0.7 for males, 0.6 for females). After drinking, the blood ethanol concentrations were measured using headspace gas chromatography/flame ionization detection. ResultsThe measured maximum BACs of the elderly participants were significantly higher (α=0.01) than the target BAC (mean maximum BAC and range: 0.627g/kg, 0.3–0.81g/kg, for males: 0.616g/kg, 0.32–0.78g/kg, for females: 0.635g/kg, 0.3–0.81). The calculated Widmark factors showed a high coefficient of variation (for males: 0.7±0.138 [0.55–1.2, CV: 19.7%], for females 0.59±0.119 [0.46–1.08, CV: 20.2%]). ConclusionThe results demonstrate that BAC calculations by Widmark's equation in elderly individuals may be complicated by a high variation of Widmark factors. There is a tendency to an elevation of the actual BAC with increasing age.

Comparison of breath-alcohol screening test results with venous blood alcohol concentration in suspected drunken drivers

Hand-held electronic breath-alcohol analyzers are widely used by police authorities in their efforts to detect drunken drivers and to improve road-traffic safety. Over a three month period, the results of roadside breath-alcohol tests of drivers apprehended in Finland were compared with venous blood alcohol concentration (BAC). The mean (median) time between sampling blood and breath was 0.71h (0.58h) with a range from 0 to 6h. Some hand-held instruments gave results as the concentration of alcohol in breath and were converted into BAC assuming a blood–breath alcohol ratio (BBR) of 2260. The mean venous BAC (1.82g/kg) in traffic offenders was higher than the result predicted by the hand-held breath analyzers (1.72g/kg). In 1875 roadside tests, the relationship between venous BAC (x) and BrAC (y) was defined by the regression equation y=0.18+0.85x. The coefficients show both a constant bias (y-intercept 0.18g/kg) and a proportional bias (slope=0.85). The residual standard deviation (SD), an indicator of random variation, was ±0.40g/kg. After BAC results were corrected for the time elapsed between sampling blood and breath, the y-intercept decreased to 0.10g/kg and 0.004g/kg, respectively, when low (0.1g/kg/h) and high (0.25g/kg/h) rates of alcohol elimination were used. The proportional bias of 0.85 shows that the breath-alcohol test result reads lower than the actual BAC by 15% on average. This suggests that the BBR of 2260 used for calibration should be increased by about 15% to give closer agreement between BAC and BrAC. Because of the large random variation (SD±0.40g/kg), there is considerable uncertainty if and when results from the roadside screening test are used to estimate venous BAC. The roadside breath-alcohol screening instruments worked well for the purpose of selecting drivers above the statutory limit of 0.50g/kg.

The separate effects of self-estimated and actual alcohol intoxication on risk taking: A field experiment.

Many risky actions are carried out under the influence of alcohol. However, the effect of alcoholic intoxication over the willingness to take risks is complex and still remains unclear. We conduct an economic field experiment in a natural, drinking and risk-taking environment to analyze how both actual and self-estimated blood alcohol concentration (BAC) levels influence subjects’ choices over monetary lotteries. Our results reveal a negative impact of both actual and self-estimated BAC levels on risk-taking. However, for male and young subjects, we find a positive relationship between BAC underestimation (a pattern of estimation error which mainly occurs at high BAC levels) and the willingness to choose riskier lotteries. Our findings suggest that a risk compensation mechanism is activated only when individuals’ own intoxication level is consciously self-perceived to be high. We conclude therefore that human propensity to engage in risky activities under the influence of alcohol is not due to an enhanced preference for risky choices. In addition to the suggestion in the existing literature that such propensity is due to a weakened ability to perceive risks, our results indicate that an impaired self-perception of own intoxication level may also be an important factor.

The Consequences of Providing Drinkers With Blood Alcohol Concentration Information on Assessments of Alcohol Impairment and Drunk-Driving Risk

We examined the effect of providing drinkers with blood alcohol concentration (BAC) information on subjective assessments of alcohol impairment and drunk-driving risk. We sampled 959 drinking participants from a natural drinking environment and asked them to self-administer a personal saliva-based alcohol test. Participants then were asked to rate their alcohol impairment and to indicate whether they could drive legally under one of four BAC feedback conditions (assigned at random): (1) control condition (no BAC feedback provided before the ratings); (2) categorical BAC information (low, high, and highest risk) from the saliva test; (3) categorical BAC information corroborated by a calibrated police breath alcohol analyzer; and (4) precise (three-digit) BAC information from the breath alcohol analyzer. Both control participants and participants who received precise BAC feedback gave subjective impairment ratings that correlated with actual BACs. For participants who received categorical BAC information from the saliva test, subjective impairment did not correlate with the actual BAC. Providing drinkers with BAC information, however, did help them predict more accurately if their BAC was higher than the legal BAC driving limit. Although BAC information can influence drinkers' assessments of alcohol impairment and drunk-driving risk, there is no strong evidence that personal saliva-based alcohol tests are particularly useful.

Assessing the value of environmental prevention programmes in reducing driving under the influence (DUI) among college students

There is increasing concern, particularly in Europe, at the high levels of drinking in young people of college age. This level is not only high, but is on the increase. A recent survey (2004) by the European School Survey Project on Alcohol and Other Drugs (ESPAD) focused on 35 countries [1]. The survey, which looked at the habits of teenagers, found 26% of boys and 29% of girls in the United Kingdom had indulged in binge drinking at least three times in the previous month. For the purposes of the study, binge drinking was classed as having more than five alcoholic drinks in a row. Correspondingly high levels of drinking were found in Central European and Nordic countries. In the United States [2] and elsewhere, this high level of drinking has been associated with increased levels of driving after drinking alcohol. A more recent study [3] found positive relationships between modes of drinking behaviours and driving under the influence (DUI) of alcohol. In that study, heavy episodic drinking, frequency of drinking, variance of drinking and drinks per occasion all predicted DUI. Notwithstanding the value of these studies in linking drinking behaviour with drinking and driving, it needs to be borne in mind that such studies are invariably based on self-report, and the definitions of drinking after driving and DUI are not always well defined or consistent. Furthermore, similar terms such as driving while intoxicated/impaired (DWI) are frequently used, but again inconsistently defined. Measurements of actual blood alcohol concentration (BAC) in drivers, where obtainable, are much to be preferred. In the past, DUI prevention efforts have rarely targeted college students, although environmental DUI prevention campaigns have been shown to be effective in community settings. In particular, the Community Trials Project [4, 5] used a model of increased enforcement of DUI laws supported by media advocacy to reduce alcohol-related accidents. Conceptually, the combination of media coverage/campaigns and DUI checkpoints result in increased perceptions of the risk of arrest for DUI in the general population which, in turn, leads to reduced DUI and accident rates. In this issue, Clapp and colleagues [6] report on the first study to test the efficacy of an environmental DUI prevention intervention in a college community. The results, which were again based on self-report surveys, compare reported drinking after driving of an experimental group of students at a college exposed to an intervention programme with those at a college without such a programme. The results reveal a considerable drop in self-reported driving after drinking following the DUI prevention campaign at the intervention campus. However, no similar drop was found at the comparison university. Furthermore, analysis of perceived risk for DUI arrest revealed a statistically significant increase in risk perception before and after survey at the experimental, but not in the control campus. Given the high levels of drinking world-wide among students of college age, account should also be taken of lessons from more general drink driving interventions. A recent special issue of the journal Traffic Injury Prevention[7] focused on alcohol and drug-impaired driving. This issue contains up-to-date international reviews of drink driving interventions, which although not specific to young college students, are likely to be widely applicable to this group of drivers. These include reviews of world-wide trends in drinking and driving, preventing drink driving using alcohol policy, preventing alcohol-related injury: a health promotion approach, sobriety checkpoints: evidence of effectiveness, and the prevention of young driver's DWI: a social–sequential model. Further studies are needed to test environmental DUI prevention campaigns across different college settings and student groups, both in the United States and in Europe. Ideally, these studies should use roadside surveys of blood alcohol concentration [8] rather than self-report surveys to assess actual DUI. Such surveys show that the levels of BAC vary widely across age and Socio-Economic group (SEG). These conclusions are also likely to be applicable to variations in the student population. Furthermore, measures of BAC level provide a much better measure of actual road safety risk associated with alcohol and this risk has been recently reassessed and documented [9]. Finally, the value of such surveys would be greatly enhanced if they were linked to attitudinal and behavioural studies of student drivers which could throw light on the aetiology of DUI in this very important group. Specific countermeasures and preventative programmes could then be drawn up to address the problem more effectively.

Using calculations to estimate blood alcohol concentrations for naturally occurring drinking episodes: a validity study.

The purpose of this study is to determine the accuracy of retrospective estimated blood alcohol concentrations (eBACs) for re-creating intoxication resulting from a naturally occurring drinking event. This study identified five eBAC equations, applied them to self-report data and compared the results to actual blood alcohol concentration obtained by a breath test. A convenience sample of 109 drinkers was recruited near drinking establishments and asked to provide breath alcohol concentration (BrAC) samples. Participants were contacted by telephone on the next waking day to gather data required for five algorithms that determine eBAC. BrAC and eBAC obtained from each equation were compared to determine the level of agreement between the two approaches. eBACs correlated highly with each other (r > or = 0.99); R2 for all algorithms ranged from 0.54 to 0.55 with BrAC as the criterion. On average, eBAC equations overestimated BrAC. Regression analysis identified the amount of time spent drinking, number of standard drinks, weight and year in school as factors related to discrepancy. These data indicate that, although all equations produce eBACs that are highly related, their relationship to BrAC does vary across equations. Using the best fitting equation, eBAC is more strongly correlated with BrAC when intoxication is less than 0.08 g/210 L of breath, and the magnitude of the relationship decreases as intoxication rises.

Potential Risks of Providing Drinking Drivers with BAC Information

The objective of this paper is to discuss the benefits and risks of providing drinkers with tools that allow them to estimate their blood alcohol concentration (BAC), and to examine the field usability of one commercially available tool. Drinking and driving laws are specified in terms of the driver's BAC, and there is concern that the absence of a method for drivers to accurately estimate their BAC level limits their ability to determine whether they can drive legally. A number of devices that provide a method for the individual to estimate or measure their BAC have been developed. Although some of these devices—such as the “know your limit” (KYL) cards—have been widely distributed, their effectiveness in encouraging good driving decisions have rarely been tested. This article describes a pilot study on the field usability of the Guardian Angel (GA) personal alcohol test in a field setting. The GA test analyzes saliva samples from drinking and indicates under which BAC category they fall (.00−.04; .04−.08; .08+). The research examined whether drinkers could, in natural drinking environments, correctly administer and interpret the test results. The methodology involves sampling drinkers on a weekend night on and around the grounds of a large West Coast university as they traveled between off-campus parties, bars, and their dorms. They were asked to assess their own intoxication and impairment, then self-administer and interpret the Guardian Angel test. After interpreting the test, participants were asked to reassess their intoxication and impairment levels, and were given a breath BAC test using a calibrated unit. The results revealed that although the majority of drinkers' were able to administer the GA test, their interpretations did not correspond with actual BACs. The interpretations of the GA test produced false-negatives, underestimating actual BACs. Drinkers perceived themselves to be less intoxicated, on average, after interpreting the GA test results. In conclusion, this research addresses potential pros and cons of providing BAC information to drinkers. It underscores the importance of testing BAC estimation tools under field conditions and the potential risks associated with tests that do not produce accurate results.

Field assessment of BAC data to study late-night college drinking.

This field study of late-night college drinking sought to (1) test the ability of the 5+/4+ measure to screen for higher levels of intoxication and (2) examine the relation between estimated and actual blood alcohol concentration (BAC). During a 15-week spring semester, college students returning to their residence halls between 10:00 PM and 3:00 AM on Wednesday through Saturday nights were anonymously interviewed to collect BAC and self-report data (n = 1,020). Although 70.9% had not been drinking on Wednesday nights, a majority of the intercepted students had been drinking on the other three nights. Mean BACs on these three nights were in a moderate range (48 to 51 mg/dl), but the 5+/4+ measure classified many students as heavy episodic drinkers at relatively low BACs. For example, 66.3% of those meeting the 5+/4+ criterion for the night had BACs < 100 mg/dl. Students with BACs ranging from 70 to 90 mg/dl exhibited the greatest accuracy in estimating their BAC; those with lower BACs tended to overestimate their level of intoxication; whereas those with higher BACs tended to underestimate it. Field assessment of student intoxication is an important tool for examining research questions in college drinking. The 5+/4+ measure classifies many college students as heavy episodic drinkers, even though their intoxication level is below conventional thresholds used to define drunkenness. In addition, there is a discernible pattern of BAC estimation in the field that corresponds to intoxication level.

Evaluating alleged drinking after driving--the hip-flask defence. Part 1. Double blood samples and urine-to-blood alcohol relationship.

This two-part article examines the strengths and weaknesses of various ways of investigating claims of drinking alcohol after driving, commonly known as the hip-flask or glove-compartment defence. In many countries the onus of proof in hip-flask cases rests on the prosecution. With good co-operation from the police and timely sampling of body fluids, such as blood and urine for forensic analysis of ethanol, useful evidence can be mustered to support or challenge the truthfulness of alleged drinking after driving. The person's blood-alcohol concentration (BAC) can be compared with values expected on the basis of the amount of alcohol consumed after driving, according to theoretical Widmark calculations. The actual BAC measured is then adjusted for the additional amount of alcohol consumed in the after-drink. Double blood samples, that is, taking two specimens of venous blood about 30-60 minutes apart and looking at the magnitude and direction of change in BAC provides little or no more information than a single blood specimen. However, the relationship between alcohol in blood and urine is very useful in hip-flask cases whereby the concentration expected in the primary urine is compared with the concentration in the bladder urine voided. The concentration of alcohol determined in a second urine sample collected 30-60 min later gives supporting evidence in hip-flask cases. A graphical method, which entails plotting ethanol concentrations in blood and urine as a function of time provides a robust and practical way to investigate hip-flask defences. In the second part of the review, congener analysis is presented, which entails comparing the concentrations of n-propanol, isobutanol and occasionally other congeners in the alcoholic beverage allegedly consumed after driving with the volatiles present in the suspect's blood and urine determined by headspace gas chromatography.

Predicting alcohol impairment: perceived intoxication versus BAC.

The purpose of this study was to report the relationship among perceived intoxication, performance impairment, and actual blood alcohol concentration (BAC) levels. Fifteen subjects, aged 21 to 40, completed both single- and double-dose sessions of alcohol consumption. BACs, reaction and anticipation time, and perceived intoxication data were collected during both sessions. Analysis of data showed that perceived intoxication was significantly related to performance impairment, but the actual BAC was not.

Accurate measurement of blood alcohol concentration with isothermal rebreathing.

The importance of interaction of exhaled air with the airway surface was evaluated by comparing the effects of different breathing maneuvers and inhaled air temperature on the relationship between breath alcohol concentration (BRAC) and blood alcohol concentration (BAC). Breath alcohol was measured with an infrared absorption unit. Blood and simulator liquid alcohol concentrations were measured by gas chromatography. Breath samples were measured after both low and high exhaled volumes and after rebreathing. Breathing maneuvers were performed after either hyperventilation, breathhold or normal breathing. Inspired air temperature was varied between 0 degree C and 40 degrees C. The rebreathing method for sampling alveolar alcohol samples was evaluated with a new isothermal rebreather that was designed to provide a substantial amount of heat to the rebreathed air in order to heat the airway surfaces. Using a single breath test, the indicated BAC values vary from 14% above the actual BAC to as low as 55% below the actual BAC. Hyperventilation caused a significant decrease in BRAC and breathhold caused a significant increase in BRAC. When isothermal rebreathing is applied to such tests, the breath test results were always within +/- 10% of the true BAC, even with an altered breathing pattern. Isothermal rebreathing provided an accurate sample of alveolar air that was not affected by altered breathing pattern or air temperature.

Computer-Aided Headspace Gas Chromatography Applied to Blood-Alcohol Analysis: Importance of Online Process Control

This paper describes the analysis of ethanol in blood specimens from suspect drunk drivers and the associated quality assurance procedures currently used in Sweden for legal purposes. Aliquots of whole blood from two separate Vacutainer tubes are diluted with 1-propanol as internal standard before analysis by headspace gas chromatography (HS-GC) with three different stationary phases: Carbopak B, Carbopak C, and 15% Carbowax 20 M. The actual HS-GC analysis, the integration of chromatographic peaks, the collection and processing of results, as well as the quality control tests involve the use of computer-aided techniques. The standard deviation of analysis(y) increased with concentration of ethanol in the blood specimen(x), and above 0.50 mg/g the regression equation was y = 0.0033 + 0.0153x. The prosecution blood-alcohol concentration (BAC) is the mean of three separate determinations made by different laboratory technicians working independently with different sets of equipment. A deduction is made from the mean analytical result to compensate for random and systematic errors inherent in the method. At BACs of 0.5 and 1.5 mg/g, which are the statutory limits in Sweden, the allowances currently made are 0.06 and 0.09 mg/g, respectively. Accordingly, the reduced prosecution BAC is less than the actual BAC with a statistical confidence of 99.9%.

Do breath tests really underestimate blood alcohol concentration?

It has been reported that in the fully postabsorptive state, breath test results underestimate actual blood alcohol concentration (BAC) in 86% of the population. Reanalysis of the data on which this conclusion was based indicates 77% of these subjects were actually underestimated, and 23% were overestimated. Further refinements indicate 68% had their actual BAC underestimated, 16% were acceptably close to the actual BAC, and 16% were overestimated. Perhaps more importantly, comparison of this data with other results indicates fully postabsorptive status may not occur until more than three hours after drinking. Consequently, breath test results may tend to overestimate actual BAC for significant amounts of time after the peak BAC has been reached.

Medicolegal alcohol determination: Widmark revisited.

Several concepts and principles advanced by Widmark over 50 years ago are briefly compared with results of recently published experimental work. His conclusions--that breath alcohol analysis can lead to overestimates of actual blood alcohol concentration, and that +/- 2 standard deviations about the average should be used to estimate certain pharmacokinetic parameters for medicolegal alcohol determinations--are supported by these more-recent experimental results.

Accuracy and precision of breath-alcohol measurements for a random subject in the postabsorptive state.

The accuracy of estimates of blood-alcohol concentration based on measurements of breath-alcohol concentration in a randomly selected subject by a random quantitative evidential breath-alcohol analyzer is evaluated with respect to the breath analyzer itself, its calibration, and the biological variables of the subject being tested. There are no suitable experimental data for rigorous determination of the overall accuracy, so I estimate it from the CV of the available data. I find that the uncertainty in these breath-analyzer readings for a random subject in the postabsorptive state is at least +/- 15%, +/- 19%, or +/- 27%, depending on whether +/- 2 CV, the experimental range, or +/- 3 CV, respectively, is used to express the overall uncertainty. Over 90% of this uncertainty is due to biological variables of the subject, and at least 23% of subjects will have their actual blood-alcohol concentration overestimated. Manufacturers' specifications for the accuracy and precision of these instruments are inconsistent with the experimental values reported in the literature and I recommend that an appropriate amount of uncertainty be reflected in the results from these breath analyzers, especially when they are used for law-enforcement purposes.

Self-estimates of blood alcohol concentration in drinking-driving context

A total of 72 social drinkers between the ages of 20 and 57 years participated in an ad lib social drinking session. At various intervals throughout the session participants provided estimates of their blood alcohol concentration (BAC) along with breath samples for objective determination of their BAC. Participants were classified into three groups, based on the pattern of their BAC estimation errors — Underestimators, Overestimates, or Mixed Pattern estimators. Underestimators consumed more alcohol and attained higher BACs during the drinking session than the other two groups. Underestimators also rated their level of intoxication significantly lower than other groups and were most likely to judge themselves fit to drive when their actual BAC was in excess of the statutory limit.

Alcohol consumption and response in men social drinkers; the effects of causal attributions concerning relative response control.

An experiment is reported that was designed to observe the degree of self-control that subjects would choose to exert over their intoxication in a permissive situation. It was predicted that subjects who perceived that they appeared to be relatively less intoxicated than their peers would display less of a change, following alcohol consumption, in behaviors believed to be normally altered. Of particular interest was the role that attributions of causality for sobriety or drunkenness would play in relation to subsequent control over intoxication. It was predicted that self-attributions would result in enhanced or continued control. The clearest demonstration that individuals can self-induce sobriety was expected to be obtained from subjects who were considered drunk but who received information which contradicted an external attribution for this behavior. Finally, self-control was expected to lead to an unwillingness to continue drinking only if that self-control were attributed to personal initiative. Results showed that subjects who were led to attribute responsibility for level of intoxication to themselves rather than to amount of alcohol consumption experienced a greater level of sobriety. Decisions on future alcohol-related behavior were also influenced by these factors and not simply by actual blood alcohol concentration.