Experimenter Expectancy Effect

Siu L. Chow

doi:10.4135/9781071812082

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Experimenter Expectancy Effect

Author:Siu L. Chow
In:The SAGE Encyclopedia of Research Design
Chapter DOI:https://doi.org/10.4135/9781071812082.n198
Subject:Research Methods & Evaluation (general), Research Design
Keywords:attention span; expectancy effects; experimenter effects

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The experimenter’s expectancy effect is an important component of the social psychology of the psychological experiment (SPOPE), whose thesis is that conducting or participating in research is a social activity that might be affected subtly by three social or interpersonal factors, namely, demand characteristics, subject effects, and the experimenter’s expectancy effects. These artifacts call into question the credibility, generality, and objectivity, respectively, of research data. However, these artifacts may be better known as social psychology of nonexperimental research (SPONE) because they apply only to nonexperimental research.

The SPOPE Argument

Willing to participate and being impressed by the aura of scientific investigation, research participants may do whatever is required of them. This demand characteristics artifact creates credibility issues in the research data. The subject effect artifact questions the generalizability of research data. This issue arises because participants in the majority of psychological research are volunteering tertiary-level students who may differ from the population at large.

As an individual, a researcher has profound effects on the data. Any personal characteristics of the researcher may affect research participants (e.g., ethnicity, appearance, demeanor). Having vested interests in certain outcomes, researchers approach their work from particular theoretical perspectives. These biases determine in some subtle and insidious ways how researchers might behave in the course of conducting research. This is the experimenter expectancy effect artifact.

At the same time, the demand characteristics artifact predisposes research participants to pick up cues about the researcher’s expectations. Being obligingly ingratiatory, research participants “cooperate” with the researcher to obtain the desired results. The experimenter expectancy effect artifact detracts research conclusions from their objectivity.

SPOPE Revisited—SPONE

Limits of Goodwill

Although research participants bear goodwill toward researchers, they may not (and often cannot) fake responses to please the researcher as implied in the SPOPE thesis.

To begin with, research participants might give untruthful responses only when illegitimate features in the research procedure render it necessary and possible. Second, it is not easy to fake responses without being detected by the researcher, especially when measured with a well-defined task (e.g., the attention span task). Third, it is not possible to fake performance that exceeds the participants’ capability.

Nonexperiment Versus Experiment

Faking on the part of research participants is not an issue when experimental conclusions are based on subjects’ differential performance on the attention span task in two or more conditions with proper controls. Suppose [Page 533][Page 534][Page 535]that a properly selected sample of boys is assigned randomly to the two conditions in Table 1. Further suppose that one group fakes to do well, and the other fakes to do poorly. Nonetheless, it is unlikely that the said unprincipled behavior would produce the difference between the two conditions desired by the experimenter.

Table 1 The Basic Structure of an Experiment
Control Variable
Test Condition	Independent Variable	IQ	Sex	Age	Control Procedure	Dependent Variable
Experimental	Drug	Normal	M	12–15	Random assignment	Longer attention span
Control	Placebo	Normal	M	12–15	Repeated measures	Shorter attention span

Table 2 A Schematic Representation of the Design of Goldstein, Rosnow, Goodstadt, and Sul’s (1972) Study of Verbal Conditioning
Subject Group	Experimental Condition (Knowledgeable of verbal conditioning)	Control Condition (Not knowledgeable of verbal conditioning)	Mean of Two Means	Difference Between Two Means
Volunteers	${\bar{X}}_{1} (6)$	${\bar{X}}_{2} (3)$	$\bar{X} (4.5)$	$d_{1} = {\bar{X}}_{1} - {\bar{X}}_{2} (6 - 3) = 3$
Nonvolunteers	${\bar{Y}}_{1} (4)$	${\bar{Y}}_{2} (1)$	$\bar{Y} (2.5)$	$d_{2} = {\bar{Y}}_{1} - {\bar{Y}}_{2} (4 - 1) = 3$

Source: Goldstein, J. J., Rosnow, R. L., Goodstadt, B., & Suls, J. M. (1972). The “good subject” in verbal operant conditioning research. Journal of Experimental Research in Personality, 6, 29–33.

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Entry

Reader's guide

Entries A-Z

Subject index

Experimenter Expectancy Effect

The SPOPE Argument

SPOPE Revisited—SPONE

Limits of Goodwill

Nonexperiment Versus Experiment

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