Lab Experimentation

1. Lab Experimentation Prof. Xiao-Ping Chen University of Washington

2. Lab Experiment: the tradeoff Advantages Testing causal effects • Allow for rigorous control to rule out alternative explanations • Isolate the phenomenon, focus on key variables, and eliminate/ neutralize the influence of irrelevant extraneous variables • Conducive to examine mediating processes • Precision of measurement • Study behavior itself instead of self-reports of behavior

3. Lab experiment: the tradeoff Disadvantages • Reactivity of the participant • Limitations posed by ethics • Human subjects committee • Consent from participants • Artificiality of environment • Seldom suited to studying long-term effects

4. Should I do a lab experiment? • Depends on your research objective • Parameter estimation research • Hypothesis testing research • Whether causal effect is of the primary interest

5. Cover story and experimental context 1.Experimental realism is the key, mundane realism is a plus 2.Provide a believable context for introducing manipulations, experimental tasks, and dependent measures and must be credible throughout the experiment 3.Hide research hypotheses from the subjects (i.e., guard demand characteristics) 4.Try to reduce the reactivity of the participant (e.g., evaluation apprehension)

6. Experimental manipulation 1.Construct validity is the key 2.Investigate previous research to see how they did it and then use your creativity 3.Use multiple operations/ methods if possible

7. Team Cooperation

8. Prisoner’s dilemma Your Partner’s Choice C D $7 $10 Your C $7 $2 Choice $2 $4 D $10 $4

9. Social Dilemma Mean Contribution of Other Members Your Contribution 0 1 2 3 … 10 0 10 11.67 13.33 15.0 … 26.67 1 9.33 11.0 12.67 14.33 … 26.0 2 8.67 10.33 12.0 13.67 … 25.33 3 8.0 9.67 11.33 13.0 … 24.67 ………………… 10 3.33 5.0 6.67 8.33 … 20.0 Your Payoff = (10 – C) + 2* [(n-1) MC + C] / n

10. Pillutla and Chen (1999): Social norms and cooperation in social dilemmas: The effects of context and feedback Experimental ImplicitPerceived Condition Norm Norm Economic Comp. Coop.or comp. Non-Econ. Coop.Coop. or comp.

11. Pillutla and Chen (1999) 第一阶段 第二阶段 实验条件 经济情景 社会情景 1 （不合作反馈) 32.35% 29.56 2 （合作反馈） 29.68 49.39 3 （无反馈） 27.54 36.52 社会情景 经济情景 4 （合作反馈） 43.04 51.67 5 （不合作反馈） 39.61 11.69 6 （无反馈） 32.08 39.58

12. Chen, Bussmann, & Bachrach (2007): Reciprocity in ultimatums: the effects of fairness perceptions, negative emotions, and partner closeness • Multi-operations of reciprocity: • Acceptance/ rejection decision • Reciprocating amount • Intention for a long-term relationship

13. Chen, Bussmann, & Bachrach (2007): Reciprocity in ultimatums: the effects of fairness perceptions, negative emotions, and partner closeness • Experimental design: • 2 x 3 factorial • Proposed amount: • 35%, 50%, or 65% • Partner relationship: • stranger or friend • Measures: • Fairness perception • Negative emotion • Partner closeness

14. Chen, Bussmann, & Bachrach (2007): Reciprocity in ultimatums: the effects of fairness perceptions, negative emotions, and partner closenessHypothesized structural model with parameter estimates

15. Chen, Bussmann, & Bachrach (2007): Reciprocity in ultimatums: the effects of fairness perceptions, negative emotions, and partner closeness • Post-hoc structural model with parameter estimates

16. Conclusion • Experiments can be used to rigorously test causal effects of variables; and to test mediating or moderating effects • Experiments are a lot of fun!