Experimental setup. (A) Example stimuli used for the X-ray luggage-screening task. During the normative rating task, participants rated 320 X-ray luggage images (120 target: 60 high clutter, 60 low clutter; 200 non-target: 100 high clutter, 100 low clutter) that contained everyday objects (hair-dryers, clothes, etc.) and a possible target present (five different knives, with one possible per image) based on clutter, difficulty and confidence in finding the knife. (B) Decision matrix. Breakdown for each advice type given during the experiment. (C) X-ray luggage-screening task. During each trial, participants would first see a fixation cross, advice from one of the agents to “search” or “clear” the bag, an image of the X-ray luggage bag, a decision to accept or reject the advice of the agent to “search” or “clear” the bag, fixation crosses, feedback indicating if their decision was correct or incorrect and lastly, fixation crosses.