Attention bias occurs when certain salient stimuli disproportionately capture cognitive resources, overshadowing equally relevant information and altering decision-making processes. This chapter examines this phenomenon through the historical case of prefrontal lobotomy, whose rapid spread in the first half of the twentieth century was driven by excessive focus on successful cases reported by its main proponents, while complications and adverse outcomes were downplayed. The historical review demonstrates how the combination of social expectations, sensationalist media coverage, and clinical belief led to the acceptance of a procedure with limited evidence and serious consequences. The neurocognitive definition of attention bias is discussed, along with its evolutionary origins and mechanisms, which can be measured using classic paradigms such as the stroop effect and the dot-probe task. The chapter also explores its impact on modern life and medical practice, where it can distort clinical judgment, favor decisions driven by emotional stimuli, or selectively direct attention toward risks or benefits. finally, practical strategies to mitigate this bias are presented, including mindfulness, checklists, structured variable analysis, and consulting divergent perspectives.