Expectations of how machines use individuating information and base-rates

Machines are increasingly used to make decisions. We investigated people’s beliefs about how they do so. In six experiments, participants (total N = 2664) predicted how computer and human judges would decide legal cases on the basis of limited evidence — either individuating information from witness testimony or base-rate information. In Experiments 1 to 4, participants predicted that computer judges would be more likely than human ones to reach a guilty verdict, regardless of which kind of evidence was available. Besides asking about punishment, Experiment 5 also included conditions where the judge had to decide whether to reward suspected helpful behavior. Participants again predicted that computer judges would be more likely than human judges to decide based on the available evidence, but also predicted that computer judges would be relatively more punitive than human ones. Also, whereas participants predicted the human judge would give more weight to individuating than base-rate evidence, they expected the computer judge to be insensitive to the distinction between these kinds of evidence. Finally, Experiment 6 replicated the finding that people expect greater sensitivity to the distinction between individuating and base-rate information from humans than computers, but found that the use of cartoon images, as in the first four studies, prevented this effect. Overall, the findings suggest people expect machines to differ from humans in how they weigh different kinds of information when deciding.