The automatic influence of advocacy on lawyers and novices.

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.