According to John Zaller and Stanley Feldman in A Simple Theory of the Survey Response: Answering Questions versus Revealing Preferences, people normally don’t have a “single, fixed, and firm attitude on issues but instead have many, potentially opposing considerations”. That is, most people have mixed feelings about policies and political issues - not counting ideologues and political activists, who tend to view ambivalence as a weakness easily exploited by one’s adversaries.
Surveys usually ask for straightforward opinions as if respondents did have single, fixed and firm attitudes about the subject at hand. Respondents often answer such questions as if this assumption were true, by weighing the pros, cons and whatnots, then endorsing an answer that best reflects the sum of the parts. In other words, they are able to answer simple-minded survey questions by averaging across the considerations that are salient at the moment of response.
And what is salient can be manipulated by how survey questions are framed, as well as the order of questions. For example, by asking about political affiliation first, a survey primes responses to be more ideologically consistent than if questions about the respondents’ politics were left for the end of the survey.
Based on Zaller and Feldman’s review of the literature, here’s more on how individuals - in general and on average - respond to survey questions:
People who are more politically aware have more considerations at the top of their heads and available for use in answering survey questions.
People who have greater interest in an issue have more thoughts about that issue readily accessible in memory than other persons, all else equal.
There are strong correlations between the ideas at the top of people's minds as they answer survey items and their responses to the items themselves.
There exists a fair amount of over-time instability in people's attitude reports.
Opinions that are subject to repeated measurement have central tendencies that are stable over time, but fluctuate around these central tendencies.
Reported attitudes of politically aware persons exhibit greater over-time stability than those of less-aware persons.
People have more stable responses to closed-ended policy items concerning issues close to their everyday concerns.
Greater ambivalence is associated with higher levels of response instability.
Raising new considerations in immediate proximity to a question affects the answers given by making different considerations salient.
People who are ambivalent on an issue are most affected by manipulations that raise new considerations in immediate proximity to a question about the issue.
Inserting the name of a prominent politician or group into a question affects the public's responses to the question (the "endorsement effect").
The race of an interviewer sometimes affects the responses to questions which he or she asks.
Manipulations that raise the salience of a reference group can affect responses to questions on which the reference group has a well-known position.
News reports can "prime" certain ideas, thereby making them more accessible for use in formulating attitude statements on related subjects (the "priming effect").
Question order can "prime" certain ideas, thereby inducing correlations with proximate related items.
Inducing individuals to think about their ideological orientation in close proximity to questions having ideological content can "prime" ideology for use in answering those questions
Interestingly, Zaller and Feldman could not confirm that inducing people to think more carefully about an issue before stating an opinion would enhance the reliability of reported opinions, meaning that respondents would be more likely to give the same answer when asked the same question later. In fact, Zaller and Feldman found the opposite to be the case: when people were instructed to think carefully about an issue, they were more likely to change their answers later on. Zaller and Feldman were puzzled by this finding, but I’m not. The more you think about something, the more you realize it’s complicated and the realization of complexity does not favor fixed and firm attitudes about that thing.
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Reference:
Zaller, John, and Stanley Feldman. “A Simple Theory of the Survey Response: Answering Questions versus Revealing Preferences.” American Journal of Political Science 36, no. 3 (1992): 579–616. https://doi.org/10.2307/2111583 (cited by 1997 as of April3, 2022, per Google Scholar)