Experiments in psychology and economics

Experiments are very common in psychology and increasingly so in economics particularly in areas like behavioural economics and neuroeconomics which would hardly exist without them. The abstracts of papers in such fields often make quite grand claims for the implications of their results. Leaving aside the question of ecological validity - whether you are going to behave the same in the real world as when lying prostrate in an MRI scanner - there is an important question of how culturally general one's results are.
A favourite task in experiments is the Ultimatum Game. It turns out that a characteristic finding in experiments conducted in the US (that the first movers irrationally offer too much and the second movers irrationally reject what they regard as too little) is not replicated in one study in the Peruvian Amazon. The Machiguenga tribe behave much more like economists would predict which is somewhat ironic since they have probably managed to avoid any exposure to the dismal science.