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Trust and reciprocity: are effort and money equivalent?

Vilares I, Dam G, Kording K - PLoS ONE (2011)

Bottom Line: Here we studied a trust game based on physical effort and compared the results with those of a computationally equivalent monetary trust game.We found no significant difference between effort and money conditions in both the amount trusted and the quantity reciprocated.Our results validate the use of trust games to study exchanges in physical effort and to characterize inter-subject differences in trust and reciprocity, and also suggest a new behavioral paradigm to study these differences.

View Article: PubMed Central - PubMed

Affiliation: Department of Physical Medicine and Rehabilitation, Rehabilitation Institute of Chicago, Northwestern University, Chicago, Illinois, United States of America. iris-vilares@northwestern.edu

ABSTRACT
Trust and reciprocity facilitate cooperation and are relevant to virtually all human interactions. They are typically studied using trust games: one subject gives (entrusts) money to another subject, which may return some of the proceeds (reciprocate). Currently, however, it is unclear whether trust and reciprocity in monetary transactions are similar in other settings, such as physical effort. Trust and reciprocity of physical effort are important as many everyday decisions imply an exchange of physical effort, and such exchange is central to labor relations. Here we studied a trust game based on physical effort and compared the results with those of a computationally equivalent monetary trust game. We found no significant difference between effort and money conditions in both the amount trusted and the quantity reciprocated. Moreover, there is a high positive correlation in subjects' behavior across conditions. This suggests that trust and reciprocity may be character traits: subjects that are trustful/trustworthy in monetary settings behave similarly during exchanges of physical effort. Our results validate the use of trust games to study exchanges in physical effort and to characterize inter-subject differences in trust and reciprocity, and also suggest a new behavioral paradigm to study these differences.

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Quantity sent back by the trustee, which is considered a measure of (absolute) reciprocity.A) Average reciprocity in the monetary and the effort conditions (black and white, respectively). No significant difference was found comparing the monetary and effort conditions (p = 0.9519; paired t-test; n = 30). Error bars represent s.e.m. B) Cumulative distribution function for the amount returned by the trustee for the monetary (solid line) and the effort (dashed line) conditions. The distribution functions are not statistically different (p = 0.76, two-sample Kolmogorov-Smirnov test; n = 30).
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pone-0017113-g003: Quantity sent back by the trustee, which is considered a measure of (absolute) reciprocity.A) Average reciprocity in the monetary and the effort conditions (black and white, respectively). No significant difference was found comparing the monetary and effort conditions (p = 0.9519; paired t-test; n = 30). Error bars represent s.e.m. B) Cumulative distribution function for the amount returned by the trustee for the monetary (solid line) and the effort (dashed line) conditions. The distribution functions are not statistically different (p = 0.76, two-sample Kolmogorov-Smirnov test; n = 30).

Mentions: We also wanted to know if reciprocating behavior differs between a monetary and an effort condition. We found that subjects reciprocated in both conditions (Fig. 3a), returning μ$ = 4.9±0.6 $ in the monetary condition and μw = 4.8±0.6 EB in the effort condition. The averages were again significantly different from zero, the Nash equilibrium (p-val$ = 1.6×10−6 and p-valw = 2.5×10−6, Wilcoxon signed-rank test). The same is observed if we look at the relative reciprocity (μ$ = 0.49±0.03$ and μw = 0. 54±0.05 EB, p-val$ = 1.5×10−6 and p-valw = 2.4×10−6, Wilcoxon signed-rank test). No significant difference in absolute reciprocity was found comparing the monetary and effort conditions (p-val = 0.95; paired t-test). Comparing relative reciprocity, there might be a trend for reciprocating more in the effort condition, but the difference is not significant (p-val = 0.27; paired t-test). Looking at the cumulative distribution functions of monetary versus effort reciprocity (see Fig. 3B) no significant difference can be found (p-val = 0.76, two-sample Kolmogorov-Smirnov test). A power analysis (as above) gives an upper limit of 14%, so any real difference, if it exists, should be smaller than that value. These results indicate that reciprocity does not differ significantly between the monetary and effort conditions, and in both cases subjects reciprocated more than predicted by Nash equilibrium.


Trust and reciprocity: are effort and money equivalent?

Vilares I, Dam G, Kording K - PLoS ONE (2011)

Quantity sent back by the trustee, which is considered a measure of (absolute) reciprocity.A) Average reciprocity in the monetary and the effort conditions (black and white, respectively). No significant difference was found comparing the monetary and effort conditions (p = 0.9519; paired t-test; n = 30). Error bars represent s.e.m. B) Cumulative distribution function for the amount returned by the trustee for the monetary (solid line) and the effort (dashed line) conditions. The distribution functions are not statistically different (p = 0.76, two-sample Kolmogorov-Smirnov test; n = 30).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3045406&req=5

pone-0017113-g003: Quantity sent back by the trustee, which is considered a measure of (absolute) reciprocity.A) Average reciprocity in the monetary and the effort conditions (black and white, respectively). No significant difference was found comparing the monetary and effort conditions (p = 0.9519; paired t-test; n = 30). Error bars represent s.e.m. B) Cumulative distribution function for the amount returned by the trustee for the monetary (solid line) and the effort (dashed line) conditions. The distribution functions are not statistically different (p = 0.76, two-sample Kolmogorov-Smirnov test; n = 30).
Mentions: We also wanted to know if reciprocating behavior differs between a monetary and an effort condition. We found that subjects reciprocated in both conditions (Fig. 3a), returning μ$ = 4.9±0.6 $ in the monetary condition and μw = 4.8±0.6 EB in the effort condition. The averages were again significantly different from zero, the Nash equilibrium (p-val$ = 1.6×10−6 and p-valw = 2.5×10−6, Wilcoxon signed-rank test). The same is observed if we look at the relative reciprocity (μ$ = 0.49±0.03$ and μw = 0. 54±0.05 EB, p-val$ = 1.5×10−6 and p-valw = 2.4×10−6, Wilcoxon signed-rank test). No significant difference in absolute reciprocity was found comparing the monetary and effort conditions (p-val = 0.95; paired t-test). Comparing relative reciprocity, there might be a trend for reciprocating more in the effort condition, but the difference is not significant (p-val = 0.27; paired t-test). Looking at the cumulative distribution functions of monetary versus effort reciprocity (see Fig. 3B) no significant difference can be found (p-val = 0.76, two-sample Kolmogorov-Smirnov test). A power analysis (as above) gives an upper limit of 14%, so any real difference, if it exists, should be smaller than that value. These results indicate that reciprocity does not differ significantly between the monetary and effort conditions, and in both cases subjects reciprocated more than predicted by Nash equilibrium.

Bottom Line: Here we studied a trust game based on physical effort and compared the results with those of a computationally equivalent monetary trust game.We found no significant difference between effort and money conditions in both the amount trusted and the quantity reciprocated.Our results validate the use of trust games to study exchanges in physical effort and to characterize inter-subject differences in trust and reciprocity, and also suggest a new behavioral paradigm to study these differences.

View Article: PubMed Central - PubMed

Affiliation: Department of Physical Medicine and Rehabilitation, Rehabilitation Institute of Chicago, Northwestern University, Chicago, Illinois, United States of America. iris-vilares@northwestern.edu

ABSTRACT
Trust and reciprocity facilitate cooperation and are relevant to virtually all human interactions. They are typically studied using trust games: one subject gives (entrusts) money to another subject, which may return some of the proceeds (reciprocate). Currently, however, it is unclear whether trust and reciprocity in monetary transactions are similar in other settings, such as physical effort. Trust and reciprocity of physical effort are important as many everyday decisions imply an exchange of physical effort, and such exchange is central to labor relations. Here we studied a trust game based on physical effort and compared the results with those of a computationally equivalent monetary trust game. We found no significant difference between effort and money conditions in both the amount trusted and the quantity reciprocated. Moreover, there is a high positive correlation in subjects' behavior across conditions. This suggests that trust and reciprocity may be character traits: subjects that are trustful/trustworthy in monetary settings behave similarly during exchanges of physical effort. Our results validate the use of trust games to study exchanges in physical effort and to characterize inter-subject differences in trust and reciprocity, and also suggest a new behavioral paradigm to study these differences.

Show MeSH