Base Rate Neglect is a cognitive bias that occurs when people ignore the general probability of an event occurring and instead focus on specific information that is presented to them. This can lead to faulty decision-making and inaccurate judgments. For example, if a person is told that a certain disease is rare, but then learns that a close friend has been diagnosed with the disease, they may become overly concerned about their own risk of developing the disease, even if their personal risk is still very low. One reason why people may be prone to base rate neglect is that they often rely on anecdotal evidence and personal experiences to make judgments, rather than statistical data. Additionally, people may be more likely to focus on information that is emotionally salient or vivid, rather than information that is more abstract or difficult to process. Base rate neglect can have serious consequences in a variety of contexts, such as medical decision-making, financial planning, and legal judgments. For example, a doctor who ignores the base rate of a disease may order unnecessary tests or treatments, leading to increased healthcare costs and potential harm to the patient. To overcome base rate neglect, it is important to consider both the specific information presented and the general probability of an event occurring. This can involve seeking out statistical data and avoiding overreliance on anecdotal evidence. Additionally, decision-makers can benefit from training in statistical reasoning and critical thinking.
cognitive bias, decision-making, statistical data, anecdotal evidence, emotional salience
Base Rate Neglect is an example of a cognitive bias and logical fallacy. It means that people often ignore a helpful piece of information when making decisions. For example, an 8 year old might think that they have a really good chance of winning a game of chance, even if they know that the odds are actually very low. They may have heard from their friends that they have won before, but ignore the fact that lots of other people have lost. This can lead to them making bad decisions and not getting the results that they hoped for.
Base Rate Fallacy, Statistical Ignorance, Unreliable Evidence, Overconfidence.
CITATION : "Thomas Lee. 'Base Rate Neglect.' Design+Encyclopedia. https://design-encyclopedia.com/?E=214127 (Accessed on July 16, 2025)"
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