This is like a Sally-Ann problem for scientists. The Sally-Ann problem is used to test "theory of mind" in autists: the subject watches Sally place a ball in box A and leave the room. Ann enters the room and removes the ball, placing it in box B. Sally returns to the room, looking for her ball. Which box will she open first? Those supposedly without "theory of mind" will answer box B, because that's where the ball is…
Maybe we should just strip this back to actual facts. Scientists observed that subjects in a trial typically spent 250ms longer choosing between a free KitKat & Mars bar (that they may receive after the experiment), than they did on choosing between two groups of random dots on a screen.