Lost Letter Technique

Lost Letter Technique Definition

Lost Letter TechniqueThe lost letter technique is used to measure people’s attitudes by dropping stamped letters addressed to various organizations in public areas and then recording how many of the letters are returned via the mail. It is assumed that people will be more likely to return a letter if it is addressed to an organization that they support than if it is addressed to an organization they do not support. For example, a Democrat who finds a lost letter should be more likely to mail it when it is addressed to a Democratic candidate’s headquarters than to a Republican candidate’s headquarters.

Lost Letter Technique History and Modern Usage

In one of the first studies to use the lost letter technique, Stanley Milgram and his colleagues dropped stamped letters in a variety of public locations. The letters were addressed to one of four recipients: “Medical Research Associates,” “Friends of the Communist Party,” “Friends of the Nazi Party,” or a private individual. People were less likely to return the letters if they were addressed to the Communist Party (25% returned) or the Nazi Party (25% returned) than if they were addressed to the Medical group (72% returned) or the private individual (71% returned). These results suggest that people were less likely to mail letters to organizations they did not support.

To verify that the response rates reflected people’s attitudes, Milgram conducted additional studies. In one study, the researchers were able to correctly predict U.S. presidential election results in different election wards using the lost letter technique. Letters addressed to the Committee to (a) Elect (Barry) Goldwater, (b) Defeat Goldwater, (c) Elect (Lyndon) Johnson, and (d) Defeat Johnson were dropped in various election wards. Election wards that supported Johnson in the election were more likely to return the pro-Johnson and anti-Goldwater letters than the pro-Goldwater/anti-Johnson letters. The opposite results were found in wards that ended up supporting Goldwater in the election.

Later researchers have used the lost letter technique to study helping behavior. By varying the characteristics of the letters, researchers can identify the factors that increase the chances that people will help by mailing the letter. Some of these studies have used post cards and e-mails instead of sealed letters. This modification has allowed researchers to determine the impact of the type of message on helping behavior.

The lost letter technique allows researchers to determine people’s attitudes or the factors that influence helping behavior without directly asking them (known as an unobtrusive measure). Because participants are unaware that they are participating in a study, they will not alter their behavior to “look good” for the experimenter.


  1. Milgram, S., Mann, L., & Harter, S. (1965). The lost-letter technique: A tool of social research. Public Opinion Quarterly, 29, 437-438.
  2. Vaes, J., Paladino, M. P., & Leyens, J. P. (2002). The lost e-mail: Prosocial reactions induced by uniquely human emotions. British Journal of Social Psychology, 41, 521-534.

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