It has long been known that advocating for a cause can alter the advocate’s beliefs. Yet a guiding assumption of many advocates is that the biasing effect of advocacy is controllable. Lawyers, for instance, are taught that they can retain unbiased beliefs while advocating for their clients and that they must do so to secure just outcomes. Across ten experiments (six preregistered; N = 3,104) we show that the biasing effect of advocacy is not controllable but automatic. Merely incentivizing people to advocate altered a range of beliefs about character, guilt and punishment. This bias appeared even in beliefs that are highly stable, when people were financially incentivized to form true beliefs and among professional lawyers, who are trained to prevent advocacy from biasing their judgements.

长期以来，人们都知道，为某项事业辩护可以改变拥护者的信念。然而，许多倡导者的一个指导性假设是倡导的偏见效应是可控的。例如，律师被教导他们可以在为客户辩护的同时保持公正的信念，并且他们必须这样做才能确保获得公正的结果。在十个实验（六个预注册；N  = 3,104）中，我们表明倡导的偏见效应不是可控的，而是自动的。仅仅激励人们倡导改变了一系列关于性格、内疚和惩罚的信念。这种偏见甚至出现在高度稳定的信念中，当人们在经济上受到激励以形成真正的信念时，以及在专业律师中，他们接受过培训以防止宣传使他们的判断产生偏见。