Asking questions changes behavior: mere measurement effects on frequency of blood donation

Health Psychol. 2008 Mar;27(2):179-84. doi: 10.1037/0278-6133.27.2.179.


Objective: This research examined the impact of completing a questionnaire about blood donation on subsequent donation behavior among a large sample of experienced blood donors.

Design: Participants (N=4672) were randomly assigned to an experimental condition that received a postal questionnaire measuring cognitions about donation or a control condition that did not receive a questionnaire.

Main outcome measures: Number of registrations at blood drives and number of successful blood donations were assessed using objective records both 6 months and 12 months later.

Results: Findings indicated that, compared to control participants, the mean frequency of number of registrations at blood drives among participants in the experimental group was 8.6% greater at 6 months (p<.0.007), and was 6.4% greater at 12 months (p<.035). Significant effects were also observed for successful blood donations at 6 months (p<.001) and 12 months (p<.004).

Conclusion: These findings provide the first evidence that the mere measurement is relevant to promoting consequential health behaviors. Implications of the research for intervention evaluation are discussed.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Blood Donors / psychology*
  • Blood Donors / statistics & numerical data
  • Female
  • Follow-Up Studies
  • Health Knowledge, Attitudes, Practice
  • Humans
  • Intention
  • Male
  • Middle Aged
  • Persuasive Communication*
  • Program Evaluation
  • Surveys and Questionnaires*