VOL.87 NO.5 PALFREY AND PRISBREY:PUBLIC GOODS EXPERIMENTS 84 1 noise.... no noise 0.75 0.5 0.25 -15 0 5 0 10 15 20 FIGURE 6.EXPECTED SPENDING:PERIOD 10.EXPERIENCED You ll be aid IN CASH at the end of the nount of mo the incentives and motivations for individuals on the decisions other people make. 【1s1m u a portant that you do not talk a the utility according to the specific rules of esides this the methodological lesson from the experiment.If you have a question,feel this experiment should be clear.It is indeed free to raise your hand One of us will come als of indive over to w you are sitting and answer your And. thes can the be used to distinguish be ken down into a sequence of four se tween different theoretical explanations for in roum across subjects that is ments.Everyone you are under noob s ho of these phenomena. you will be paid 11 cents for every 100 FRANCS you have accumulated during the APPENDIX course of all Sample Instructions from 4/9/92(read aloud) ps of four persons each.Those This is an experiment in decision-making. wot, 87 NO. 5 PALFREY AND PRISBREY: PUBUC GOODS EXPERIMENTS 0.75 expected contribution 0.5 0.25 \ no no no se -15 -10 -5 0 5 10 15 20 FIGURE 6. EXPECTED SPENDING: PERIOD 10, EXPERIENCED Notes: The noise curve assumes subjects make errors as in probit model 3. The no-noise curve assumes the subjects make no errors. The curves here represent an experienced population in period tO. While more research obviou.sly remains to be done before we have a complete picture of the incentives and motivations for individuals to contribute to public goods, quite a bit has been learned here, particularly about the role of nonmonetary components of the utility function and the role of subject decision errors. Besides this, the methodological lesson from this experiment should be clear. It is indeed possible to design experiments where the de￾tails of individual decision rules can be accu￾rately measured. And, furthermore, these measurements can be used to distinguish be￾tween different theoretical explanations for in￾teresting systematic features in the aggregate data. Given the considerable amount of het￾erogeneity of behavior across subjects that is known to be characteristic of these experi￾ments, improved measurement at the individ￾ual level would seem to be a necessary ingredient to reaching a better understanding of these phenomena. APPENDIX Sample Instructions from 4/9/92 (read aloud) This is an experiment in decision-making. You will be paid IN CASH at the end of the experiment. The amount of money you earn will depend upon the decisions you make and on the decisions other people make. It is im￾portant that you do not talk at all or otherwise attempt to communicate with the other sub￾jects except according to the specific rules of the experiment. If you have a question, feel free to raise your hand. One of us will come over to where you are sitting and answer your question in private. This session you are participating in is bro￾ken down into a sequence of four separate ex￾periments. Each experiment will last ten rounds. At the end of the last experiment, you will be paid the total amount you have accu￾mulated during the course of all four experi￾ments. Everyone will be paid in private and you are under no obligation to tell others how much you earned. Your eamings are given in FRANCS. At the end of the last experiment, you will be paid 11 cents for every 100 FRANCS you have accumulated during the course of all four experiments. In each experiment you will be divided into four groups of four persons each. Those groups will stay the same for all ten rounds of the experiment. After each ten-round