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2 results

  • 11 - Experimenter Effects

  • from Part II - The Building Blocks of a Study
  • Edited by Austin Lee Nichols, Central European University, Vienna, John Edlund, Rochester Institute of Technology, New York
  • Book:
    The Cambridge Handbook of Research Methods and Statistics for the Social and Behavioral Sciences
    Published online:
    25 May 2023
    Print publication:
    08 June 2023, pp 224-243

  • Summary

    As social and behavioral scientists, it is of fundamental importance to understand the factors that drive the behaviors that we measure. Careful design is thus required to minimize the influence of extraneous factors. Yet, we often overlook one major class of such extraneous factors – those related to us, the experimenters. Experimenter effects can potentially arise at every step in the research process – from the selection of hypotheses, to interacting with research participants in ways that might alter their behavior, to biases in data interpretation. While such experimenter-driven effects often occur without notice, and without ill intent, they nonetheless threaten the replicability and generalizability of research. In this chapter, we discuss when and how such effects arise, preventative measures that can be taken to reduce their influence, and methods for accounting for such effects, when appropriate.

  • Expectancy Effects in Self-Help Depression Treatment: First Evidence that the Rationale Given for an Online Study Impacts the Outcome

  • Barbara Cludius, Johanna Schröder, Steffen Moritz
  • Journal:
    Behavioural and Cognitive Psychotherapy / Volume 46 / Issue 2 / March 2018
    Published online by Cambridge University Press:
    30 October 2017, pp. 195-208
    Print publication:
    March 2018

  • Background: Positive expectations play an important role in effective treatments for major depressive disorder (MDD). The way a study is contextualized modulates prognostic expectations. Aims: The aim of the study was to test the effect of differing information regarding the rationale given to participants for a study on depression symptoms. Method: Sixty-nine participants with depression symptoms participated in an online study with two conditions. In random order, half were invited to participate in a treatment study and half in a cognition study. After completing the baseline assessment, participants received one of two self-help manuals. Post-assessment was conducted six weeks later. Results: Only about 64% of the participants were reached for post-assessment, and adherence was low. However, our results offer the first evidence that stronger improvements emerged in participants who were told the trial was a treatment study compared with a cognition study. Conclusion: Information given about the rationale for a study could influence symptom reduction in online treatments for patients with MDD. Future (online) studies should attempt to replicate these results.