When faced with risk, human beings do not respond only to probabilities. They respond to a perception of danger shaped by their emotions, experience, level of trust and sense of control.

The Nuclear Safety and Radiation Protection Authority’s 2025 Barometer https://www.asnr.fr/actualites/barometre-asnr-2025-sur-la-perception-des-risques-par-les-francais shows that people in France do not assess all risks on the same scale. Their judgement depends on the severity they imagine, the visibility of the danger and the credibility they attribute to institutions.

This study also highlights the central role of trust. Among those surveyed, 64 per cent say they trust scientific institutions. Some 88 per cent want understandable information about risks.

Before a crisis: turning knowledge into preparedness

Knowing about a risk is not enough to prepare for it. Rare but very serious events are often downplayed, particularly because of optimism bias. This leads people to believe that misfortune is more likely to affect others than themselves.

The European Union Civil Protection Knowledge Network https://civil-protection-knowledge-network.europa.eu/behavioural-insights-disaster-resilience points out that simply disseminating information rarely produces adequate preparedness. To prompt action, instructions must be concrete, accessible and easy to follow.

Exercises and scenarios help turn an abstract threat into behaviours that people can draw on. They establish automatic responses and reduce the number of decisions that will have to be improvised under pressure.

When risk materialises, behaviour changes

As a threat draws nearer, attention focuses on the most immediate signals. Some people act quickly. Others wait for confirmation, observe those close to them or continue their usual activities.

This waiting does not necessarily indicate an absence of fear. It may stem from difficulty interpreting an ambiguous situation or a desire to preserve a sense of normality.

The European Commission https://cordis.europa.eu/programme/id/HORIZON_HORIZON-CL3-2022-DRS-01-04 emphasises that responses depend on how information is presented, its accessibility, the social context, past experience and the level of trust in the authorities.

During a crisis: making decisions under stress

Acute stress is first and foremost an adaptive response. It activates the amygdala, the hypothalamus and the autonomic nervous system, along with hormones such as adrenaline and cortisol.

An Inserm collective expert review https://www.inserm.fr/wp-content/uploads/media/entity_documents/inserm-ec-2011-stresstravailsantesituationindependants-synthese.pdf describes the central role of the prefrontal cortex in processing information and making decisions during this biological response.

When stress becomes too intense or prolonged, thinking may become more rigid. Working memory, the ability to compare different solutions and an overall understanding of the situation may be impaired.

In this context, an effective organisation reduces complexity. It clarifies responsibilities, limits unnecessary information and sets priorities that can be understood immediately.

The European Centre for Disease Prevention and Control https://www.ecdc.europa.eu/sites/default/files/documents/recommendations-preparedness-planning-public-health-threats.pdf recommends transparent communication that is tailored to different audiences and focused on action. Acknowledging uncertainty strengthens trust more than creating an artificial impression of certainty.

After a crisis: learning without looking for someone to blame

Emerging from a crisis involves more than returning to normal. It must provide an opportunity to understand the decisions made, the constraints encountered, the signals overlooked and the adaptations that actually worked.

The National Institute for Industrial Environment and Risks https://www.ineris.fr/fr/facteurs-organisationnels-humains-guide-evaluation-foh-processus-retour-experience-apres-evenement recommends a lessons-learned review focused on facts and on technical, human and organisational factors. The objective is not to immediately identify someone responsible, but to identify the conditions that produced the decisions observed.

Behavioural science thus teaches us that resilience begins long before a crisis. It is built through credible information, realistic exercises, clear responsibilities and a real collective capacity to learn.

For METRICS, the challenge can be summed up as follows: a better understanding of behaviour in the face of risk makes it possible to anticipate a crisis better, make better decisions when it occurs and prepare better for the one that might follow.

Main references

1. ASNR, 2025 Barometer on risk perception among people in France https://www.asnr.fr/actualites/barometre-asnr-2025-sur-la-perception-des-risques-par-les-francais

2. Inserm, Collective expert review on stress, its biological mechanisms and its effects on health https://www.inserm.fr/wp-content/uploads/media/entity_documents/inserm-ec-2011-stresstravailsantesituationindependants-synthese.pdf

3. European Commission, Behavioural sciences and disaster preparedness https://civil-protection-knowledge-network.europa.eu/behavioural-insights-disaster-resilience

4. European Commission, Behavioural and psychological responses in crisis situations https://cordis.europa.eu/programme/id/HORIZON_HORIZON-CL3-2022-DRS-01-04

5. European Centre for Disease Prevention and Control, Recommendations for preparedness for health threats https://www.ecdc.europa.eu/sites/default/files/documents/recommendations-preparedness-planning-public-health-threats.pdf

6. Ineris, Guide to human and organisational factors in lessons-learned reviews https://www.ineris.fr/fr/facteurs-organisationnels-humains-guide-evaluation-foh-processus-retour-experience-apres-evenement