Effect of Experimenter's Expectancy in Relation to Type and Structure of the Experimental Task

Shames, Morris L.; Adair, John G.

doi:10.2466/pr0.1980.46.2.487

Cited by 2 publications

(3 citation statements)

References 19 publications

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“…The expectations of study physicians and raters have been shown to bias their evaluations of patients in research studies. 16,17 For example, clinical response rates in single-blind placebo-controlled studies are higher than in double-blind studies, possibly because clinicians and raters in single-blind studies know the patients' treatment assignment. 18 This bias may result from investigators' investment in their research and desire to prove or disprove the hypothesis being studied.…”

Section: Introductionmentioning

confidence: 99%

Expectancy and the Treatment of Depression: A Review of Experimental Methodology and Effects on Patient Outcome

Rutherford¹,

Wager²,

Roose³

2010

CPSR

115

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Expectancies are a class of psychological and neurobiological processes that may be responsible for part of the improvement observed with psychiatric treatments. Patients' expectations can substantially affect the results of clinical trials, and managing them is an important part of clinical care. This review describes the history of research on expectancy effects in Major Depressive Disorder (MDD), the relationship between expectancies and placebo effects, and what is currently known about the mechanisms of action of expectancy. Meta-analyses of antidepressant trials show that placebo response rates are high (typically ~30%) and often larger than the difference in response rates between drug and placebo (typically ~10%). Some of the response to placebo is due to natural history, but a growing literature suggests that much of the improvement on placebo treatment is due to active neurobiological processes related to expectancy. Several studies have shown that higher expectation of therapeutic improvement leads to greater improvement in psychiatric symptoms, particularly in MDD. New research on the mechanisms of action of expectancy is therefore a priority that could lead to improved interventions. This review discusses the evidence to date and methodological considerations in the design of new studies.

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Section: Introductionmentioning

confidence: 99%

Expectancy and the Treatment of Depression: A Review of Experimental Methodology and Effects on Patient Outcome

Rutherford¹,

Wager²,

Roose³

2010

CPSR

115

View full text Add to dashboard Cite

show abstract

“…Research also suggests that experimenter expectancy effects may differ based on the experimental task. For example, Shames and Adair (1980) tested expectancy effects with two tasks: an ambiguous task (i.e., person perception) and a factual task (i.e., number estimation). For each task, experimenters believed that participants would score either high (overestimate) or low (underestimate).…”

Section: Experimental Concerns: Experimenter Expectancy Effectsmentioning

confidence: 99%

“…Researchers must also avoid the almost inevitable effects of experimenters’ expectations. This is especially true when experimental tasks are more ambiguous or subjective (e.g., Shames & Adair, 1980). In general, research assistants should remain blind to all experimental details, and they should only receive information necessary for them to successfully conduct the experiment.…”

Section: Best Practices For Laboratory Researchmentioning

confidence: 99%

Practicing What We Preach (and Sometimes Study): Methodological Issues in Experimental Laboratory Research

Nichols

Edlund

2015

Review of General Psychology

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At the core of any causal claim is an experimental study, and laboratory research often provides the most valid arena for conducting experiments. Laboratory experiments allow researchers to provide internal validity to any phenomena they examine. However, researchers must consider and address certain methodological concerns when conducting lab research. Before participants ever agree to participate, forces are beginning to affect how they will respond to experimental manipulations. These and additional concerns continue during and after the completion of the experiment, yet many researchers do not fully understand their implications. As serious as these issues have always been, the introduction of social media and Internet data collection only highlight the importance of understanding and addressing methodological issues in laboratory experiments. In the following article, we discuss potential methodological flaws in laboratory research, examine research relevant to these problems, review evidence that suggests problems actually do contaminate our data, and suggest areas for future research. We conclude by providing recommendations for eliminating or alleviating these problems in future research, considering the role of replication studies as a post-hoc means of detecting these issues, and apply our conclusions to experimental research performed outside or a laboratory. In all, we believe that addressing these concerns in experimental research and practice will strengthen the validity of our conclusions, the replicability of our findings, and science as a whole.

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Effect of Experimenter's Expectancy in Relation to Type and Structure of the Experimental Task

Cited by 2 publications

References 19 publications

Expectancy and the Treatment of Depression: A Review of Experimental Methodology and Effects on Patient Outcome

Expectancy and the Treatment of Depression: A Review of Experimental Methodology and Effects on Patient Outcome

Practicing What We Preach (and Sometimes Study): Methodological Issues in Experimental Laboratory Research

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