Fig 2. (Left) Sound stimuli and paradigm design.

(Right) Laboratory version of the experiment: subjects viewed the above image of a radio-telescope and were given the following instruction: “A radio-telescope located in Cambridge captured a series of radio signals from outer space. You will listen to these sounds and your task is to think and decide if they were produced by good-friendly or bad-aggressive aliens”. Participants had to select their answer for each sound block using an 11-point scale (mouse click), which appeared onscreen immediately after a sound block was played (the side of ‘good’ and ‘bad’ alien was semi-randomized).