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References on Drugs and Driving

The Bases of Decisions Leading to Alcohol Impaired Driving

AJ McKnight, EA Langston, AS McKnight and JE Lange

National Public Services Research Institute, 8201 Corporate Dr., Landover MD, 20785 USA


Using a Critical Incidents approach, 600 drivers were called upon to identify the bases of decisions to drink and drive. In an unstructured interview, each driver described the bases for decisions leading to specific instances of impaired driving, including decisions regarding participation in drinking events, transportation to events, plans prior to and following initiation of drinking, activities while drinking, leaving the drinking event, and transportation following drinking. Over 12,000 individual decision bases were described. While the bases were highly specific to the individual decisions, those involving the social environment exerted the strongest influence, followed in decreasing order by influences of a personal nature, the occasion giving rise to drinking, economic considerations, plans already made, and usual patterns of behaviour. Results showed that the likelihood of alcohol impaired driving is largely determined by decisions made well in advance of the act itself. Reducing this likelihood requires (1) modifying early decisions as to events attended, mode of transportation, and selection of companions, (2) preventing hosts and friends from inadvertent encouragement to drink heavily or to drive after doing so, (3) advance planning of alternatives to drinking and/or driving, and (4) helping drinkers and those around them to redefine "responsibilities" with respect to acts that ultimately lead to alcohol impaired driving.


While extensive research has provided an abundance of information as to the conditions surrounding drinking and driving, it has not provided a complete and detailed picture of the bases underlying drinking-and-driving decisions. A method that is widely used to identify conditions contributing to a particular phenomenon is the critical incident technique. This approach, which has been in use for over 50 years, examines conditions surrounding specific critical incidents of the phenomenon under examination, and aggregates information across individual incidents to discover general contributing factors. The objective of this research was to use a critical incident technique in identifying decisions leading to instances of alcohol-impaired driving and to ascertain the bases of these drinking-driving decisions.


Some 600 drivers who reported having driven an automobile while impaired by alcohol were interviewed concerning the decisions leading up to their most recent episode of alcohol-impaired driving. The drinking drivers were obtained from random telephone solicitation, remedial programs for Driving-While-Intoxicated (DWI) first-offenders, and random roadside breath testing. This activity took place in five locations as follows: Telephone solicitation - Chapel Hill, North Carolina and Greater Washington, DC (125 interviews each), DWI first-offender programs - Oakland, California and communities throughout Mississippi (125 each) and Roadside breath testing - Canton, Ohio (100).

Drivers who acknowledged having driven while impaired by alcohol were asked to agree to a 45 minute unstructured interview concerning events leading to the impaired driving. For drivers identified through DWI programs and the roadside breath tests, the event was that which led to their involvement in the program or testing. For those responding to the random telephone solicitation, it was their most recent instance of alcohol-impaired driving. The interview addressed the seven key points in the sequence of decisions leading up to alcohol-impaired driving including: Events - decisions about participating in the events that lead to drinking and driving (e.g., whether to go, where to go, etc.); Transportation to - decisions about transportation to the events (e.g., whether to drive or ride, whether to turn over keys); Planning - decisions about the nature and amount of drinking made prior to the event (e.g., whether to bring alcohol, whether to drink before starting out); Drinking - decisions about drinking made at the event (e.g., when to start, setting a limit, slowing down, stopping, switching drinks); Activities - decisions regarding participation in other activities which may affect the level of alcohol impairment (e.g., eating, dancing, drinking games); Leaving - decisions regarding leaving the drinking location (e.g., whether to leave, where to go); and Transportation from -decisions regarding driving after drinking (e.g., whether to drive or ride).

The interviews were tape recorded in their entirety and transcribed into written, narrative form. The descriptions were then reviewed by project staff in order to generate classification schemes for decisions and decision bases at each of the seven key decision point. Once the classification schemes were generated, they were used in coding the narrative descriptions. Across the entire sample, over 12,000 individual decision bases were recorded. After all of the interviews at each location were completed, interviewers met with a representative of the project staff to relate insights realized through the interview process but not manifest in the interviews themselves.


Probably the most important discovery in the analysis of decision bases is the extent to which decisions quite removed in space and time from the act of alcohol impaired driving predispose an individual to its occurrence. Early decisions as to what kind of events to attend, where they are held, who will do the driving, whom to go with, how to get there, and what to do once there frequently create a situation in which over-consumption of alcohol and subsequent driving are almost certain to occur.

The reasons that subjects gave for their decisions at various choice points along the path to impaired driving are too numerous to be related individually and yet too specific to be informatively generalized. The following summary can only describe decision bases in broad categories, conveying specifics only through examples. The various categories will be presented in decreasing order of frequency across the seven decision points.

Social-Environmental Influences

By far the most frequently cited influences on drinking and driving decisions appear to have come from environmental influences, primarily those of a social nature. In deciding whether or not to attend an event at which drinking will occur, social influences included overt encouragement by friends and the prospect of meeting friends and acquaintances. Social influences also appear to have played a significant role in transportation, drinkers riding with others because there was room in the car, because the driver wanted company, or because people were traveling as a group. In the plans that immediately preceded drinking, social influences were largely passive, that is, being influenced simply by the drinking behavior of others and being where alcohol was served. Once drinking commenced, social influences included having drinks offered or directly provided by others, being where others were drinking or having others buying rounds, and the general atmosphere of a large party where people were having a good time. When it came time to leave, social influences were prominent, including the host's or someone else's suggestion that they leave, or a generally unpleasant social environment. Finally, social influences on driving after drinking included direct suggestions or requests that the drinker do the driving, being in a social situation in which driving home was more or less expected and, in a few cases, the mere absence of any suggestion that the individual not drive.

Personal Influences

Internal, personal factors were second in their prominence upon drinking driving decisions. In decisions to attend an event, they included a desire to be with friends and acquaintances, to find entertainment or food, to visit family members, to purchase alcohol, and other miscellaneous objectives. In the decision to drink, internally-generated influences included the simple desire to achieve relaxation, to feel the effects of alcohol, to achieve a particular mood or mood change, or to satisfy the taste for a particular beverage. As to the actual drinking itself, personal decision influences were most frequently cited, including the desire to drink or to continue drinking, the desire for a particular beverage, feeling bad and wanting to feel better, feeling good and wanting to maintain it, feeling sick and needing to stop, being thirsty, and having attained the desired level of inebriation. Personal influences also came to the fore in the decision to leave a place where one had already been drinking, the specific bases including the desire to be somewhere else, feeling the effects of alcohol, fatigue, boredom, and the desire to go home.


The next most frequent decision basis was the nature of the occasion that prompted the drinking. The influence of occasions was greatest in initial decisions to attend a drinking event, where participation in the event was determined by specific occasions recognized as "special" events such as family reunions, birthdays, holidays, work-related, events, and farewells. Occasions that were infrequently mentioned as an influence were leisure time activities such as playing games or watching sports on television, and regularly scheduled events such as happy hours and Friday night parties.

Availability and Economics

How much one intended to drink was influenced by whether alcohol was provided by someone else, its price in relation to quality and quantity received, and absolute price - in that order. In actual drinking, sheer availability or plentitude was considered frequently, followed by cost. Lack of availability was an occasional consideration in the cessation of drinking. When it came to transportation, the availability and cost of alternative transportation ranked second in frequency to social influences in deciding how to get to and from a drinking event.

Prior Planning

Many reported that their decision to attend a drinking event was part of a larger plan, while relatively fewer indicated that the decision was of the "spur-of-the-moment" type. When making plans to drink, previous plans were the single leading decision influence, the majority of drinkers intending to consume only modest amounts of alcohol. Advanced planning infrequently played a role in actual drinking, deciding when to leave, or what form of transportation to take.

Usual Behavior

Deciding when and where to drink often involved doing what the individual usually did under the circumstances that prevailed. Continuation of usual, typical behavior patterns also applied to the choice of transportation, the decision of how much and what to drink, and the manner in which one actually drank, although in these decisions it played a relatively minor role. Subjects who made decisions based on normal or past behavior were similar to those who made decisions based upon personal influences.


Implications of interview results for addressing the problem of alcohol impaired driving arise largely out of detail that is not necessarily apparent in the summaries of decision bases. The most salient of these implications involve early decisions, social intervention, and alternatives to drinking and driving.

Early Decisions

Those decisions early in the chain of events leading to drinking often virtually assure that it will result in impaired driving. In most instances of alcohol impaired driving, the likelihood that the driver would drink enough to become impaired were apparent from the outset. Recognizing this, the single best decision the drinker can make is not to drive to the event. Those who drive to a drinking event are almost certain to drive home. They cannot count upon remaining sober, finding someone else to drive, or being invited to spend the night. If they cannot be dissuaded from driving, they must be convinced of the need to make firm arrangements in advance for some alternative to driving impaired. Available alternatives are discussed below.

Social Intervention

While information gathered through interviews with alcohol-impaired drivers certainly support social interventions intended to prevent drinking and driving, they also evidence a need to go further to combat what are widespread practices that actually encourage alcohol-impaired driving. Efforts to promote intervention by friends with the notion that "Friends don't let friends drive drunk" need to be expanded to include the idea that "Friends don't encourage friends to drive drunk." Two common forms of encouragement include purchasing drinks for others without knowing whether they are wanted, initiating or participating in what is destined to be a "round" of drink purchases. Discouraging this form of intervention will require overcoming belief that buying unrequested drinks is socially desirable or that declining them is socially unacceptable.

Among those who are expected to intervene in drinking and driving are hosts of events at which drinking occurs. Here too, the concept of intervention needs to be broadened to prevent inadvertently encouraging excessive drinking by displaying large quantities of alcohol or by actively "pushing" drinks as a form of hospitality, acting as if special occasions cannot be properly celebrated without the over-consumption of alcohol, and ignoring, overlooking or minimizing the seriousness of impairment signs when they become evident. Commercial establishments contribute greatly to impaired driving through quantity discounts, volume service, and unlimited quantities. Evidence from this study supports educational and regulatory measures to reduce these promotions, revealing the extent to which they contribute of alcohol impaired driving.

Alternatives to drinking and driving

Most of the subjects who acknowledged driving while impaired noted the possibility of alternatives to each that were unavailable due to lack of adequate planning. Many subjects acknowledged a willingness to accept alternatives to drinking such as non-alcoholic beverages and food had they been displayed prominently or even available. Potential alternatives to drinking cannot play a significant role in preventing alcohol-impaired driving unless the need for them is recognized in advance and provision of them is made an object of planning by hosts. The extent to which alcohol-impaired subjects became the default driver evidences the need to plan for alternatives to driving. Clearly the best alternative is not to drive at all, riding instead with someone else, thus eliminating the need for, even the possibility of, driving home. Failing that, the next best alternative is to invite as a passenger someone who does not drink at all, and turn over the keys upon arrival at the drinking event. Encouragement to planning for alternative travel arrangements need not be confined to drivers but should also be extended to passengers, many of whom end up as riding with impaired drivers for failure anticipate what is a highly probable occurrence. Advanced formal arrangements for "staying over" at the home of a host is necessary if such is to be a viable alternative to alcohol-impaired driving. Belated attempts to encourage it were too often thwarted by obligations that drivers had already incurred (e.g. to drive others home), inability of hosts to put them up, or reluctance to even ask.


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