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BHS 204-01 Methods in Behavioral Sciences I

Explore the impact of experimenter factors on ecological validity and learn ways to avoid biased interactions with subjects in experiments.

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BHS 204-01 Methods in Behavioral Sciences I

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  1. BHS 204-01Methods in Behavioral Sciences I May 21, 2003 Chapter 10 (Ray) The Ecology of the Experiment

  2. Ecology of the Experiment • Ecological validity – what is the impact of important relationships among the scientist, participant and context of the experiment. • Can be divided into: • Experimenter factors • Subject factors • Cultural and social bias

  3. Experimenter Factors • Experimenter effects – results that are due to the attitude or behavior of the experimenter, not the manipulation. • Two kinds: • Biased data collection • Influence exerted by the experimenter on the performance of the subjects.

  4. Biased Data Collection • Personal equation – constant error in observation related to individual differences. • Use two or more raters • Compare inter-rater agreement (Cohen’s kappa). • Unconscious or unintentional bias in the direction of the experimenter’s hypothesis. • Errors tend to go in the expected direction. • Acceptance or discarding of data. • Interpretation of results

  5. Biased Interactions with Subjects • Participants in experiments react differently to different experimenters. • Gender, attractiveness, dress, race, age. • Experimenters can communicate to subjects that they want them to respond differently. • Rosenthal effect • Cultural expectations • Attributions about animal behavior

  6. Ways to Avoid Bias • Expose subjects to different experimenters and different contexts and stimuli. • Keep the person interacting with subjects blind to the experimental hypothesis and to which group is the control or treatment group. • Try to see your experiment from different perspectives

  7. Kuhn’s Recommendations • Be aware of underlying assumptions and state them explicitly in papers. • The person who plans the study should not be the person who analyzes the data. • The person who plans the study should be the person who conducts it (deals with subjects). • Researchers should be pilot subjects in their own studies, to understand the experience.

  8. More Recommendations • Pilot studies should develop and rehearse standardized procedures before the actual experiment starts. • Recognize that different analysis methods may lead to different conclusions. • Good research methods are more important than finding statistically significant results.

  9. More Recommendations • Research methods should be followed to the letter and results reported honestly. • Investigators must make sure their procedures are being followed correctly during expt. • Use multiple experimenters who vary in their personal characteristics. • Keep experimenters blind whenever possible. • Seek and reward replication.

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