Social psychologists have noticed that surveys on elections usually yield rates of voting in elections that are higher than official turnout figures, a phenomenon often attributed to intentional misrepresentation by respondents who did not vote and would be embarrassed to admit it.
For example, estimates of participation in the Community Population Survey are usually higher than official election results by as much as 11%.
This paper includes a summary of the research on discrepancies between turnout and self-reporting and reports on experiments into ways to construct surveys to reduce overreporting.
Links
Holbrook, A. L. and Krosnick J. A. (2009) ‘Social Desirability Bias in Voter Turnout Reports: Tests Using the Item Count Technique’ Public Opinion Quarterly vol. 74 pp. 154-167