In cargo cult science Feynman writes:
"Millikan measured the charge on an electron by an experiment with falling oil drops, and got an answer which we now know not to be quite right. It's a little bit off, because he had the incorrect value for the viscosity of air....Why didn't they discover that the new number was higher right away? It's a thing that scientists are ashamed of--this history--because it's apparent that people did things like this: When they got a number that was too high above Millikan's, they thought something must be wrong--and they would look for and find a reason why something might be wrong. When they got a number closer to Millikan's value they didn't look so hard. And so they eliminated the numbers that were too far off, and did other things like that. We've learned those tricks nowadays, and now we don't have that kind of a disease."
What tricks is he talking about specifically? In fact, in general, what tricks do physicists learn for doing experiments and avoiding fooling themselves?
Second: it's my strong belief that Feynman is referring to something here which isn't in textbooks but instead built into the culture of physics, but I don't understand what exactly it is, and I suspect it's passed along in the culture of physics labs. If someone can explain with some stories, examples or general comments, what is that culture like?