How humans evaluate AI systems for person detection in automatic train operation: Not all misses are alike

If artificial intelligence (AI) is to be applied in safety-critical domains, its performance needs to be evaluated reliably. The present study aimed to understand how humans evaluate AI systems for person detection in automatic train operation. In three experiments, participants saw image sequences of people moving in the vicinity of railway tracks. A simulated AI had highlighted all detected people, sometimes correctly and sometimes not. Participants had to provide a numerical rating of the AI's performance and then verbally explain their rating. The experiments varied several factors that might influence human ratings: the types and plausibility of AI mistakes, the number of affected images, the number of people present in an image, the position of people relevant to the tracks, and the methods used to elicit human evaluations. While all these factors influenced human ratings, some effects were unexpected or deviated from normative standards. For instance, the factor with the strongest impact was people's position relative to the tracks, although participants had explicitly been instructed that the AI could not process such information. Taken together, the results suggest that humans may sometimes evaluate more than the AI's performance on the assigned task. Such mismatches between AI capabilities and human expectations should be taken into consideration when conducting safety audits of AI systems.