In his research, Reason has highlighted the concept of ‘defenses’ against human error within an organization, and has coined the term ‘defenses in depth’. Examples of defenses are duplicate inspections, pilot pre-flight functional checks, etc., which help prevent or ‘trap’ human errors, reducing the likelihood of negative consequences. When these defenses are weakened or breached, human error can result in incidents or accidents. These defenses have been portrayed diagrammatically as several slices of Swiss cheese - thus the model is known as the „Swiss cheese” model.