That's a good insight of how the income is perceived. If I knew I received a few days income all year long my perceived value of receiving income in the experiment is lower than what the locals would perceive since it is more variable and the risk that a long time passes before gaining income again.

Or possibly less; the implication I took was that they the cash jobs they took were supplemental income. The point of studying these villages is that they're economically isolated. They probably grow their own food, build their own shelters. I'd imagine they trade with the outside world -- using money earned from cash crops or working a few days here and there for a logging company or oil company -- for a small number of luxuries like metal, salt, or western clothing.

Money might be nice in such a situation, but if you're not going to starve to death or freeze to death and you don't have 300k$ in medical debt suffocating you, it might not be as valuable as a couple days extra pay is to a poverty-line worker in the US.