"The experiments show that small payments for correct and "don't know" responses sharply diminish the gap between Democrats and Republicans in responses to "partisan" factual question"
Different people, different answers. Plenty of people learn what to say at what point pretty darn early.
"This paper reports results from two novel experiments designed to distinguish sincere from expressive partisan differences in responses to factual questions. In both experiments, all subjects were asked factual questions, but some were given financial incentives to answer correctly. ... In our second experiment, we therefore implement a treatment in which subjects were offered incentives both for correct responses and for admitting that they did not know the correct response."
> The amount paid for “don’t know” responses was also assigned randomly, and was a fraction of the amount offered for a correct response: 20% of the payment for a correct response with probability .33, 25% with probability .33, and 33% with probability .33.
Qwrusz's comment may be relevant here.