Final answer:
Lucy's belief in her reduced vulnerability to accidents when not wearing a helmet while riding a motorcycle is an example of unrealistic optimism, which is a type of self-serving bias.
Step-by-step explanation:
Lucy's belief that she is less vulnerable to road accidents than others demonstrate the concept of unrealistic optimism. Unrealistic optimism is part of the broader category of cognitive biases known as the self-serving bias, where individuals tend to perceive themselves in overly positive ways. This often includes thinking that one is less likely to experience negative events compared to others, which could lead to risky behaviors, such as not wearing a helmet while riding a motorcycle.