The fall of the Carolingian Empire in the ninth century left Europe in turmoil. Power-hungry rulers, from counts and commanders to knights, fought incessantly for control, turning their lands into battlefields. The brutality that accompanied these power struggles was all-encompassing: homes were looted, women assaulted, crops trampled, and churches desecrated. The unarmed citizens and the church were powerless against the noblemen’s wrath. This reign of terror continued until the tenth century when a French bishop had an ingenious yet peculiar idea.

The bishop called upon local knights and nobles to gather in a field to curb the unrelenting violence. Meanwhile, priests and abbots assembled all the relics they could find—bones, bloodied rags, tiles, anything a saint had touched. The sight was both strange and solemn: these relics were said to carry sacred power, revered by the people of the time. Standing in front of this powerful display, the bishop implored the nobles to renounce their violence in the presence of these holy artifacts. In what could be considered an emotional appeal, he waved the bloody garments and bones in front of them, a gesture that undoubtedly resonated deeply with the warriors. The effect was profound. This display helped propagate the idea of the ‘Peace and Truce of God,’ and despite its superstitious nature, it effectively curbed some of the violence of the time.

While this may seem laughable from a modern perspective, where logic often reigns supreme over superstition, the emotional pull of such symbols is undeniable. It’s easy to scoff at the idea of saints’ relics having any real influence, but a psychological element persists in today’s world, even in rational minds.

The Power of Intangible Forces

Intangible forces have always shaped human behavior through religion, superstition, or culture. These forces are often invisible, but their impact on decision-making and perception is profound. They may not be scientifically measurable or directly observable, but they influence how we feel, think, and act. Humans have sought to explain the unexplainable for centuries, often attributing these unseen forces to gods, spirits, or cosmic energies. Even today, the belief in invisible powers still plays a major role in how we interact with the world, even for those claiming to be purely rational.

The idea that something as abstract as a saint’s relic could halt violence is a vivid example of the power of intangible forces. In the Middle Ages, the sight of a bone or a cloth stained with the blood of a saint would strike deep fear into warriors, causing them to halt their violent ways. While it may seem ludicrous to modern minds, the belief in the supernatural was a powerful motivating force in a time when religion dominated every facet of life. The mere thought of being cursed or displeasing a higher power was enough to change human behavior, especially when tangible consequences seemed too far removed to be immediately felt.

Fast forward to today, and the influence of intangible forces still permeates our daily lives. The idea of wearing a sweater once owned by Hitler might seem nonsensical, yet the emotional response is very real. It’s not just about the sweater—it’s about the symbolism and the emotional power attached to the association with a historical figure. The garment has no magical properties, no connection to Hitler’s essence beyond its association with him, yet it evokes a strong aversion. This response can’t be rationalized away. Even the most logically inclined individuals struggle to overcome this instinctive reaction. It’s a perfect illustration of the power intangible forces continue to exert over us despite our best efforts to rationalize them.

The Science Behind Contagion Bias

Contagion bias is the psychological phenomenon that explains how humans perceive and react to objects or people based on perceived connections, regardless of whether those connections are real or symbolic. It is one of the many cognitive biases that show how human minds are not purely logical or objective. Our decisions and emotional reactions are often influenced by factors we may not consciously recognize, and contagion bias is a prime example of this.

Research by Paul Rozin and his colleagues at the University of Pennsylvania illustrates how contagion bias works psychologically. The study asked participants to throw darts at photographs of their loved ones pinned to targets. While there was no physical harm done to the people in the photos, the participants showed marked hesitation and a drop in accuracy compared to a control group who threw darts at neutral targets. The participants acted as though they were causing harm to the people in the photos despite knowing intellectually that the dart did not affect the actual individuals. This suggests that their emotional attachment to the photos created an unconscious psychological barrier, which prevented them from acting as they would in a neutral setting.

The study also demonstrated how emotional connections to objects can override rational thinking. However, an inanimate object, a photo of a loved one, becomes imbued with meaning and significance because of its association with a person. This is a direct example of contagion bias: an object can hold power simply by being connected to someone or something with emotional significance. This bias is not about the object’s physical properties but about its symbolic weight. It’s a fundamental aspect of human psychology that connects us emotionally to objects and people in often irrational ways but deeply influential ways.

One of the most striking aspects of contagion bias is that it is not limited to personal relationships or physical objects we own. Even a distant connection to a person or event can trigger similar biases. This is seen in how certain artifacts or historical objects—like the wine glasses from Saddam Hussein’s palace—carry a weight of history that can elicit strong emotional reactions. Although no longer physically linked to the events or people they once represented, these items still carry a psychological power. Contagion bias doesn’t rely on the present or the physical; it’s about the perceived connection to something greater, often beyond conscious awareness.

Contagion Bias in Everyday Life

Contagion bias is not an abstract theory; it is a psychological phenomenon that affects our daily lives. It influences how we perceive objects, people, and experiences in ways that are not always rational or logical. One of the most fascinating aspects of contagion bias is how it shapes our responses to seemingly trivial objects. An object connected to a famous person, a historical event, or even an emotionally charged experience can elicit powerful feelings and reactions, regardless of its material value.

Take the case of the gold-plated wine glasses that once belonged to Saddam Hussein. For most people, these glasses are simply pieces of dinnerware. However, their symbolic value is immediately altered for those who learn of their origin. The glasses are no longer just decorative objects; they become part of the historical narrative of Hussein’s regime and the conflicts that surrounded it. The psychological connection to this history is powerful, influencing how we view the object, even if we know logically that the glasses themselves carry no inherent value beyond their physical properties.

This is the essence of contagion bias. It shows how we, as humans, are not only influenced by the physical attributes of objects but also by the perceived associations and emotional weight they carry. These objects transcend material value, becoming powerful symbols that shape our thoughts and feelings. In the case of the wine glasses, the emotional response to them—ranging from fascination to horror—is not about the gold or the craftsmanship but about their connection to a brutal regime and a violent historical moment.

The same bias can be seen in everyday life in how we react to objects tied to our experiences. For example, an old photograph from a happy family gathering or clothing worn during an important moment powerful emotions. These objects carry with them the memories of past experiences, and their physical state does not determine their value but the emotional significance we attach to them. Even though these objects may be worn, outdated, or damaged, their connection to our personal history can imbue them with an irrational and emotionally driven sense of importance.

Moreover, contagion bias extends beyond physical objects. It can also apply to people and their reputations. People may react negatively to someone simply because of their association with a controversial figure or event, even if they are innocent of wrongdoing. The emotional weight carried by these associations influences how we perceive others, even if those perceptions are not grounded in reality.

The Persistence of Contagion Bias

One of the most striking aspects of contagion bias is its persistence. It’s not a transient or easily overcome phenomenon; it’s ingrained in how we think and process the world. While modern society often prides itself on rationality and objectivity, the influence of contagion bias shows that human psychology is far from purely logical. Emotional connections to objects, people, and events are deeply embedded in our psyche, and they often guide our behavior in ways that seem irrational.

This persistence can be traced back to evolutionary psychology. Early human societies had to quickly assess the value of objects and people based on their associations. For instance, a weapon that belonged to a powerful leader could be seen as a symbol of strength and authority and thus might be revered. Conversely, an object tied to an enemy or a defeated foe could invoke fear or disgust. These instinctual emotional reactions were not just helpful—they were essential for survival. The ability to quickly form emotional attachments to certain items based on their symbolic power could mean the difference between life and death.

In the modern world, these deeply ingrained responses are still with us. While we no longer need to fear the weapon of an enemy tribe, we still carry emotional responses to objects and symbols associated with violence, trauma, or power. The aversion to wearing a sweater once owned by Hitler or the disgust towards the wine glasses from Saddam Hussein’s palace are contemporary examples of how contagion bias continues to influence our perceptions.

What’s even more fascinating is how contagion bias can persist even in the face of logical reasoning. We may understand that an object is not inherently harmful or valuable based on its physical attributes, yet the emotional connection—often forged through cultural, historical, or personal associations—remains. This is a testament to the strength of contagion bias and its ability to influence our behavior in ways that bypass our rational mind. Even when we consciously acknowledge that an object is no longer tied to its previous association, the emotional residue lingers, making it difficult to fully detach from the feelings it evokes.

Ultimately, the persistence of contagion bias highlights an important aspect of human nature: our minds are not entirely governed by logic and reason. We are also emotional beings, shaped by the intangible forces of culture, history, and personal experience. These forces continue to shape how we perceive the world, even when we try to distance ourselves from them. Understanding the power of contagion bias offers a deeper insight into how we relate to the objects and people around us—and how those relationships can influence our actions, often without us even realizing it.

Conclusion

Contagion bias illuminates the intricate workings of the human mind, showcasing our susceptibility to the influence of symbolism and connection. From the medieval nobles moved by relics to the modern aversion to objects associated with infamous figures, contagion bias reveals the depth of our psychological responses. By acknowledging and examining these biases, we can better understand ourselves and the world around us. So, the next time you hesitate to touch an object or feel a strong emotional response to a seemingly innocuous item, consider the powerful grip of contagion bias on the human psyche.

This article is part of The Art of Thinking Clearly Series based on Rolf Dobelli’s book.