Papers at hand:
Prior et al. and Bullock et al.
Two empirical points that we learn from the papers:
1. Partisan gaps are highly variable and the mean gap is reasonably small (without money, control condition). See also: Partisan Retrospection?
(The point is never explicitly commented on by either of the papers. The point has implications for proponents of partisan retrospection.)
2. When respondents are offered money for the correct answer, partisan gap reduces by about half on average.
Question in front of us: Interpretation of point 2.
Why are there partisan gaps on knowledge items?
1. Different Beliefs: People believe different things to be true: People learn different things. For instance, Republicans learn that Obama is a Muslim, and Democrats that he is an observant Christian. For a clear exposition on what I mean by belief, see Waters of Casablanca.
2. Systematic Lazy Guessing: The number one thing people lie about on knowledge items is that they have the remotest clue about the question being asked. And the reluctance to acknowledge ‘Don’t Know’ is in itself a serious point worthy of investigation and careful interpretation.
When people guess on items with partisan implications, some try to infer the answer using the cues in the question stem. For instance, a Republican, when asked whether unemployment rate under Obama increased or decreased, may reason that Obama is a socialist and since socialism is bad policy, it must have increased the unemployment rate.
3. Cheerleading: Even when people know that things that reflect badly on their party happened, they lie. (I will be surprised if this is common.)
The Quantity of Interest: Different Beliefs.
We do not want: Different Beliefs + Systematic Lazy Guessing
Why would money reduce partisan gaps?
1. Reducing Systematic Lazy Guessing: Bullock et al. use pay for DK, offering people small incentive (much smaller than pay for correct) to confess to ignorance. The estimate should be closer to the quantity of interest: ‘Different Beliefs.’
2. Considered Guessing: On being offered money for the correct answer, respondents replace ‘lazy’ (for a bounded rational human —optimal) partisan heuristic described above with more effortful guessing. Replacing Systematic Lazy Guessing with Considered Guessing is good to the extent that Considered Guessing is less partisan. If it is so, the estimate will be closer to the quantity of interest: ‘Different Beliefs.’ (Think of it as a version of correlated measurement error. And we are now replacing systematic measurement error with an error that is more evenly distributed, if not ‘randomly’ distributed.)
3. Looking up the Correct Answer: People look up answers to take the money on offer. Both papers go some ways to show that cheating isn’t behind the narrowing of the partisan gap. Bullock et al. use ‘placebo’ questions, and Prior et al. timing etc.
4. Reduces Cheerleading: For respondents for whom utility from lying < $, they stop lying. The estimate will be closer to the quantity of interest: 'Different Beliefs.'
5. Demand Effects: Respondents take the offer of money as a cue that their instinctive response isn’t correct. The estimate may be further away from the quantity of interest: ‘Different Beliefs.’