I'm arguing that psychological studies are bullshit because they lack any sort of scientific credibility and are notoriously unreliable. If they were using the scientific method that would be one thing, but between the sloppy methodology and poor standards you can conclude very little from them. Yes the human mind is complicated, but that's no excuse for the times where they outright ignore results which aren't convenient.
Psychological studies do use the scientific method though, at least in this case: Take a random person, show them an object and ask if they'd buy that object for $3. Repeat with a few thousand other people. Take another random person, show them the exact same object except ask if they'd buy it for $2.99. Repeat again with a few thousand other people. Do it again with two more groups at $3.99 and $4 respectively. The methodology is fairly sound and exactly the same as if it were a physics experiment: hypothesis, experiment, repeat, conclusion. It was found that people preferred the $2.99 over the $3, that the $3.99 was selected almost as often as the $3, and that the $4 was a major cut off point. If you say this is wrong then science disagrees with you: for some reason people prefer $X.99 vs $(X+1).00 more often than not.
There is nothing to debate here, this isn't opinion, it is as much a fact as the idea that a dropped object will fall to the ground.
Seasons greetings for 2013 to you too. 
