Many organizations believe that occupational accidents and resulting injuries are caused by some short coming on the part of the individual worker. The Domino Effect Theory of accident causation proposed by HW Heinrich may explain the justification for this. Preventable injuries culminate from a series of sequential events, as represented by five dominos. The first represents the task or situation, followed by some faulty worker decision, resulting in the unsafe action, which leads to an accident and the inevitable injury. By tipping the first domino all tend to fall, and by removing some of the intervening domino the accident can be eliminated. Hence the belief that workers decisions or actions are the primary cause of accidents.

The findings of two major research studies supported this conclusion.  The first by Heinrich in 1931 where he analyzed over seventy thousand accidents. He found that:

  • 88 percent of injuries resulted from actions of employees;
  • 10 percent of the accidents were traced to hazards involving the physical environment; 
  • 2 percent of the accident’s cause could not be ascertained.
  • The even larger one by FE Bird in 1966 which analyzed over 1.7 million accident reports from hundreds of companies and concluded that:
  • 95 percent of injuries resulted from actions of employees;
  • 5 percent of the accidents were traced to causes from the physical environment

These studies confirmed that most accidents were caused by some action by the worker thereby focusing intervention on changing their action or behaviors in order to reduce and eliminate accidents. 

Beliefs regarding accident causation

Accident causation may be affected by beliefs associated with: 

  • Individual factors (age, experience, personality, motivation, perception, needs, expectations, etc.),
  • Social factors (lifestyle, family issues, education, economic status, etc.) 
  • Cognitive factors (understanding, reasoning, comprehension, insight, intelligence, etc.)
  • Circumstantial factors (perceived work relationship with supervisor or peers, degree of perceived exposure, job security, etc.)
  • Organizational factors (e.g., culture, climate, management's attitude, group norms, etc.)

In many industries but especially construction, all people involved—from the organization’s workers through to executives; and partners in the supply chain have some understanding of the existence of worksite risks, but have different opinions as to how this results in accidents and injuries as well as how to best deal with this reality. This thinking (belief or bias) fundamentally impacts the way risk and safety are evaluated, addressed and the effectiveness of preventive measures devised and deployed.                                                                         

Supervision factors

The same accident may be attributed to various factors stemming from different beliefs about accident causation as held by different people (foremen, superintendents, managers, experts, safety practitioners, etc.) working on the jobsite. Prevailing wisdom attributes the cause of the accident to the decision made or behavior engaged in by the worker. This may include such things as inattention, inexperience, lack of focus, rushing, carelessness, fatigue, complacency, ignorance, not using common sense, failure to follow good work practices, or even downright stupidity to name a few. The worker may take risk for convenience, or due to happenstance.

These biases may be motivated or driven by one's belief system, one's position in the organization, or possible involvement in causation, to name a few. This posture and ultimate goal are defensive in nature. The positions of those involved will become more entrenched and will be greatly affected by the seriousness of the accident and the ultimate potential outcome of the situation.

Worker factors

The reasons given for accidents by workers provide a window into their attitudes and beliefs about safety, accident causation, or the confidence they have in their ability to deal with hazardous work situations. The worker involved in the accident may attribute the cause of the accident to operational factors, such as the need to rush in order to meet production goals, maybe the unavailability of proper tools or equipment or their condition, and a lack of protective measures or equipment, little or no concern for safety.

On the worker's part, risk taking may be associated with confidence in their ability to deal with the risks involved due to past experience, confidence in their skills, underestimating the level of the risk, or the degree of exposure. Workers who need the work will generally accept a higher level of risk, work in environments that are more hazardous, and use tools that may be inappropriate for the task, in order to meet perceived or actual expectations. Or they may simply attribute the accident to bad luck.                                   

Systems factors

Another way to look at the basic Domino Effect Theory is to look at the first domino (task or environment) and make a determination as to why the risk existed in the first place and whether it could have been eliminated or its negative impact diminished; prior to assigning the task to the worker. This is probably the most effective approach to eliminating accidents or reducing their adverse effects. This Step involves the person responsible for planning, directing, executing, and/or controlling the work.

 The next question involves the second domino and a determination should be made as to why the worker decided to proceed in the way that they did which led to the accident and the resulting injury. This requires understanding whether the worker identified the risk, was able to determine its significance, the degree of exposure, have the capability to perform the task, etc. This requires the appreciation and understanding that systems (policies, practices, and procedures) may create situations that allow risk to enter into the work process and may be the primary source of risk in the work environment.                  

Beliefs involving the impact of risk on the worker's safety and the perceived benefit of risk taking should be a factor that is assessed when considering or evaluating the motivation underlying the resulting behavior. Depending on the situation, beliefs can positively or negatively affect safety and its management. Beliefs about control are important to accident analysis and the explanations of causation. By gaining insight into such beliefs and taking those into account, accidents may be analyzed more realistically, and robust preventive measure can be devised and implemented.

The importance that beliefs play in workplace safety and its management has been identified in numerous research studies. Researchers have also verified that subjective judgment by people is a major component in any risk assessment. If such judgment is faulty, the risk management process and efforts will, in all likelihood, be misdirected and garner inferior or no beneficial results. It has been asserted that in reality, much of accident preventive measures are driven by causal inferences rather than the actual drivers of such events.