I always love seeing people's reactions to articles like this. Everyone starts crying that the study was poorly designed or some aspect of it ruined the results, regardless of whether or not they know anything about statistics or designing studies. Sure there's plenty of bad studies out there, but this one seems fine.
First off, the point of the study was not to determine whether people could tell the difference between adaptive AI and randomness. They wanted to see if the placebo effect worked in the context of video games the same way it works elsewhere. Maybe that seems obvious to you, but doing good statistics means getting data to back up what you claim.
Secondly, stop complaining about things you assume to be true and actually check the facts. Several people are talking about how the study was ruined because they had the subjects play the game twice, so maybe they just got better, etc. The 21 subjects was just the first round of the study to see if there might be anything to the idea. "A different experimental design, with 40 new subjects, confirmed the effect. This time, half of the players were put in a control group and told that the game was random, while the other half thought the game had built-in AI." There you go, problem solved.
First off, the point of the study was not to determine whether people could tell the difference between adaptive AI and randomness. They wanted to see if the placebo effect worked in the context of video games the same way it works elsewhere. Maybe that seems obvious to you, but doing good statistics means getting data to back up what you claim.
Secondly, stop complaining about things you assume to be true and actually check the facts. Several people are talking about how the study was ruined because they had the subjects play the game twice, so maybe they just got better, etc. The 21 subjects was just the first round of the study to see if there might be anything to the idea. "A different experimental design, with 40 new subjects, confirmed the effect. This time, half of the players were put in a control group and told that the game was random, while the other half thought the game had built-in AI." There you go, problem solved.