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Framing effects and gender differences in voluntary public goods provision experiments
The Journal of Socio-Economics 39 (2010) 455–457
Contents lists available at ScienceDirect
The Journal of Socio-Economics journal homepage: www.elsevier.com/locate/soceco
Framing effects and gender differences in voluntary public goods provision experiments夽 Hiroaki Fujimoto a , Eun-Soo Park b,∗ a b
Faculty of Economics, Fukuoka University, Japan Department of Economics, Missouri University of Science & Technology, Rolla, MO 65409, USA
a r t i c l e
i n f o
Article history: Received 16 April 2009 Received in revised form 27 February 2010 Accepted 14 March 2010 JEL classification: C92 D64 H41
a b s t r a c t We examine whether there are any systematic gender differences in voluntary public goods provision experiments under the two different framing conditions—the positive-frame and the negative-frame. We find that: (1) there are significant framing effects in their contribution rates for both men and women; (2) there is no significant gender difference in their contribution rates under the positive-frame and (3) there is a significant gender difference in their contribution rates under the negative-frame. In fact, women are more generous in their contribution than men under the negative-frame. © 2010 Elsevier Inc. All rights reserved.
Keywords: Public goods experiments Framing effects Gender difference
1. Introduction Are there systematic differences between genders in their cooperative or altruistic behavior? One active research area that attempts to answer this question is experimental economics. Unfortunately, experimental studies on gender effects have no consensus. In public good provision experiments, for example, Brown-Kruse and Hummels (1993) find male groups to be more cooperative than female groups. On the other hand, Nowell and Tinkler (1994) find female groups to be more cooperative than male groups and Cadsby and Maynes (1998) find no significant differences between the two groups in a series of experiments. In dictator game experiments, there are also mixed results: Bolton and Katok (1995) find no significant gender differences. However, Eckel and Grossman (1998) find all-female groups are more altruistic than all-male groups. In a variant of dictator game, Andreoni and Vesterlund (2001) find that when the price of giving is low, men appear more altruistic, and when the price is high, women are more generous. While varying the price of giving, Andreoni
夽 This research was supported by Summer Research Fund from the Department of Economics at Missouri University of Science and Technology. We would like to thank two anonymous referees for their detailed comments and suggestions. ∗ Corresponding author. E-mail addresses: [email protected] (H. Fujimoto), [email protected] (E.-S. Park). 1053-5357/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.socec.2010.03.002
and Vesterlund also find women tend to care more about equalizing payoffs. See Eckel and Grossman (2008) for a comprehensive review of works on differences between genders. In this paper, we take a look at gender differences in the context of voluntary public good provision under the two different framing conditions—a positive frame and a negative frame following Andreoni (1995). In order to examine the effects of framing on the level of cooperation in public goods experiments, Andreoni considers two different framing conditions: (1) a positive-frame condition, in which a subject’s choice is framed as contributing to a public good that makes other subjects better off and (2) a negative-frame condition, in which a subject’s choice is framed as buying a private good that makes other subjects worse off. By conducting public goods experiments under these two conditions, Andreoni finds that contribution rates are considerably lower under the negative frame condition than under the positive frame condition. Park (2000) extends Andreoni’s framing experiment to combine social psychologists’ value orientation tests with public goods experiments. He finds that there are systematic differences in framing effects across subjects with different value orientations. The main objective of this paper is to examine whether there are systematic gender differences in each of the framing conditions. The major finding of this experiment is that while there is no significant gender difference in subjects’ contribution rates under the positive-frame, there is a significant gender difference in their contribution rates under the negative-frame. In particular, women are more generous in their contribution than men under the negative-
456
H. Fujimoto, E.-S. Park / The Journal of Socio-Economics 39 (2010) 455–457
frame. Section 2 explains the experimental design and Section 3 presents the results of the experiments. 2. Experimental design 120 subjects participated in each framing condition, for a total of 240 subjects—101 female students (48 in the positive frame and 53 in the negative frame) and 139 male students (72 in the positive frame and 67 in the negative frame). All subjects were volunteers from large introductory microeconomics classes at Missouri University of Science and Technology over three semesters. The data were collected in 6 separate sessions. For each session, 40 subjects were recruited and divided randomly into two rooms of 20 each. A positive-frame experiment was conducted in one room, while a negative-frame experiment was conducted in the other room. Instructions that are nearly identical to the one used in Andreoni’s experiment (Andreoni, 1995, pp. 14–19) were used.1 The subjects were given instructions and an ‘Investment Decision Form’, which subjects used to record their decisions to allocate 60 tokens between an Individual Exchange Account and a Group Exchange Account. Our experiments closely followed that of Andreoni (1995) and the following discussion is based on Andreoni (1995, pp. 4–6): subjects played in groups of five. Each subject was given 60 tokens. In the positive-frame, every token placed in the private good xi (Individual Exchange) earns one token for subject i, while every token given to the public good gi (Group Exchange) earns one half for all five group members. (One token is worth ten cents.) Thus, subject i’s problem is to maximize i = xi +
1 1 gj gi + 2 2
(1)
j= / i
subject to the budget constraint xi + gi = 60. Thus, in this positiveframe, action of contributing to the public good would generate a positive externality for other subjects. The positive-frame instructions to subjects included “Every token you invest in the Individual Exchange will yield you a return of one. Every token invested in the Group Exchange will yield of one half for every member of the group, not just the person who invested it. It does not matter who invest tokens in the Group Exchange. Everyone will get a return from every token invested—whether they invest in the group or not.” In the negative-frame, an investment in the private good was presented as making others worse off. That is, the above positive frame can be converted into the negative frame by substituting the budget constraint of the other players, xj + gj = 60 into the objective function (1): 1 1 (60 − xj ) gi + 2 2
i
= xi +
i
1 1 = xi + gi − xj + 120. 2 2
j= / i
j= / i
This negative frame was expressed in the negative frame instructions to the subjects in the following way: “Every token you invest in the Individual Exchange will yield you a return of one. However, each token you invest in the Individual Exchange will reduce the earnings of the other players by one half each. . .. It will also be true that when the other members of your group invest in the Individual Exchange, then your earnings will be reduced by 1/2 times their investment in the Individual Exchange. . .. Every token you invest in the Group Exchange will yield a return of 1/2 for you.”
1
Instructions are available at http://www.mst.edu/ espark/frame inst.pdf.
Table 1 Framing effects. Contribution percentage
Difference at 5% level
Male
Positive-frame (52.2%) Negative-frame (23.6%)
Significant (t = 6.105; p = 0.0000)
Female
Positive-frame (49.2%) Negative-frame (34.2%)
Significant (t = 2.507; p = 0.0139)
Also, in order to provide the same incentive for the subjects under the two different frames, each subject received automatic earnings of 120 tokens to assure that the two conditions are mathematically equivalent. Unlike Andreoni’s experiment, the subjects played the game only once. This is to minimize any possible strategic and/or learning behavior. Two experimenters, one male and one female, conducted each conditioned experiment. Upon students returning the Investment Decision Form, the experimenters calculated and prepared an ‘earnings report’ for each subject. As students exit the room, they were paid privately. In order to avoid any possible “in-group” effects, no explicit or implicit emphasis on gender either during recruiting or running the experiment was made. This is different from some of the earlier experiments that compared all-male with all-female groups. 3. Results and discussions Contribution rates to the public good of all subjects (both male and female) under the positive-frame and under the negativeframe were 51.0% and 28.3%, respectively and there is a significant difference between the two rates (t = 6.108). These results are in line with findings of previous experiments (Andreoni, 1995; Park, 2000) and seem to be consistent with general findings in psychology that if the consequences of their action are positive, people feel much happier from having taken action than if the consequences are negative and the same result occurs. That is, it seems that people enjoy doing a good deed more than they enjoy not doing a bad did. As Andreoni put it aptly, the strength of the warm-glow from doing good exceeds that of the cold-prickle from doing bad. We now separate the framing effects for each gender, which is summarized in Table 1: contribution percentage of male subjects in the positive-frame and in the negative-frame are 52.2% and 23.6%, respectively and the difference is statistically significant (t = 6.105; p = 1.06 × 10−8 ). Also, contribution rates of female subjects in the two treatments are 49.2% and 34.2%, respectively, which are significantly different at the 5% level (t = 2.507; p = 0.0139). Thus, the framing effects are significant for both men and women. (Mann–Whiteny rank-sum nonparametric tests confirm qualitatively the same result.) We next look at gender differences in contribution rates while controlling for frame for each treatment. Table 2 summarizes the findings. Under the positive-frame the average contribution rate of male subjects is slightly higher than that of female subjects (52.2% and 49.2%, respectively), but there is no statistically significant difference between the two (t = 0.496). On the other hand, under the negative-frame, female subjects contributed to the public good about 45% more than male subjects and the gender difference Table 2 Gender differences in each framing condition. Contribution percentage
Difference at 5% level
Positive-frame
Male (52.2%) Female (49.2%)
Insignificant (t = 0.496)
Negative-frame
Male (23.6%) Female (34.2%)
Significant (t = 2.242; p = 0.0270)
H. Fujimoto, E.-S. Park / The Journal of Socio-Economics 39 (2010) 455–457
is statistically significant at the 5% level (t = 2.242; p = 0.0270). Thus, while there is no gender difference under the positive-frame, there is a significant gender difference under the negative-frame. (Mann–Whiteny rank-sum nonparametric tests yield qualitatively the same result.) It is rather difficult to make direct and meaningful comparisons of our results with previous public goods experiments because our experimental design is quite different from others. Instead, we make a couple of general observations regarding gender effects in each frame: first, our results do not seem to be very far off from the findings of Andreoni and Vesterlund (2001), who confirm general findings in psychology that some men are selfish and some men are altruists, while women are in general more concerned with fairness than men and tend to share evenly. In the two different frame conditions of our experiments, male subjects exhibited more contrasting contribution rates (52.2% versus 23.6%) than female subjects did (49.2% versus 34.2%). Second, our results are related to some studies in psychology that have shown that women are more prone to feel guilt than men (see, for examples, Harvey et al., 1997) and guilt often promotes constructive, other-oriented behavior (see, for example, Tangney, 1991). Andreoni describes the positive-frame as the situation of creating the warm-glow of doing something good and the negative-frame as the situation of creating the cold-prickle of doing something bad. If we are willing to agree that the negative-frame is more “guilt-inducing” than the positive-frame, then women who are more guilt-prone than men will be likely to be more cooperative in the negative-frame, which is what our results reveal. Before closing, we would like to point out some limitations of our results. Recall that in order to focus on the asymmetry between positive and negative externatlities, our experiments were designed to exclude possible learning and strategic behavior that could be observed in repeated settings. It would be an interesting topic for future research to test the extent to which our results are robust to
457
learning and continued contributions (for example, would women sustain the higher levels of contributions than men under the negative-frame even in the repeated settings?). In conclusion, we join other authors who have conducted experiments of gender effects in their general conclusion that gender difference can be an influential factor in various economic outcomes and experimenters may need to take greater care in ensuring the gender balance in their experiments and in particular, in guiltinducing situations. References Andreoni, J., 1995. Warm-glow versus cold-prickle: the effects of positive and negative framing on cooperation in experiments. Quarterly Journal of Economics 110, 1–21. Andreoni, J., Vesterlund, L., 2001. Which is the fair sex? Gender differences in altruism. Quarterly Journal of Economics 116, 293–312. Bolton, G., Katok, E., 1995. Experimental test for gender differences in beneficent behavior. Economics Letters 48, 287–292. Brown-Kruse, J., Hummels, D., 1993. Gender effects in laboratory public goods contribution: do individuals put their money where their mouth is? Journal of Economic Behavior and Organization 22, 255–267. Cadsby, C.B., Maynes, E., 1998. Gender and free riding in a threshold public goods game: experimental evidence. Journal of Economic Behavior and Organization 34, 603–620. Eckel, C., Grossman, P., 1998. Are women less selfish than men? Evidence from dictator experiments. Economic Journal 108, 726–735. Eckel, C., Grossman, P., 2008. Differences in the economic decisions of men and women: experimental evidence. In: Plott, C., Smith, V. (Eds.), Handbook of Experimental Results. Elsevier, New York, pp. 509–518. Harvey, O.J., Gore, E.J., Frank, H., Batres, A.R., 1997. Relationship of shame and guilt to gender and parenting practices. Personality and Individual Differences 23, 135–146. Nowell, C., Tinkler, S., 1994. The influence of gender in the provision of a public good. Journal of Economic Behavior and Organization 25, 25–36. Park, E.S., 2000. Warm-glow versus cold-prickle: a further experimental study of framing effects on free-riding. Journal of Economic Behavior and Organization 43, 405–421. Tangney, J.P., 1991. Moral affect: the good, the bad, and the ugly. Journal of Personality and Social Psychology 61, 598–607.
Contents lists available at ScienceDirect
The Journal of Socio-Economics journal homepage: www.elsevier.com/locate/soceco
Framing effects and gender differences in voluntary public goods provision experiments夽 Hiroaki Fujimoto a , Eun-Soo Park b,∗ a b
Faculty of Economics, Fukuoka University, Japan Department of Economics, Missouri University of Science & Technology, Rolla, MO 65409, USA
a r t i c l e
i n f o
Article history: Received 16 April 2009 Received in revised form 27 February 2010 Accepted 14 March 2010 JEL classification: C92 D64 H41
a b s t r a c t We examine whether there are any systematic gender differences in voluntary public goods provision experiments under the two different framing conditions—the positive-frame and the negative-frame. We find that: (1) there are significant framing effects in their contribution rates for both men and women; (2) there is no significant gender difference in their contribution rates under the positive-frame and (3) there is a significant gender difference in their contribution rates under the negative-frame. In fact, women are more generous in their contribution than men under the negative-frame. © 2010 Elsevier Inc. All rights reserved.
Keywords: Public goods experiments Framing effects Gender difference
1. Introduction Are there systematic differences between genders in their cooperative or altruistic behavior? One active research area that attempts to answer this question is experimental economics. Unfortunately, experimental studies on gender effects have no consensus. In public good provision experiments, for example, Brown-Kruse and Hummels (1993) find male groups to be more cooperative than female groups. On the other hand, Nowell and Tinkler (1994) find female groups to be more cooperative than male groups and Cadsby and Maynes (1998) find no significant differences between the two groups in a series of experiments. In dictator game experiments, there are also mixed results: Bolton and Katok (1995) find no significant gender differences. However, Eckel and Grossman (1998) find all-female groups are more altruistic than all-male groups. In a variant of dictator game, Andreoni and Vesterlund (2001) find that when the price of giving is low, men appear more altruistic, and when the price is high, women are more generous. While varying the price of giving, Andreoni
夽 This research was supported by Summer Research Fund from the Department of Economics at Missouri University of Science and Technology. We would like to thank two anonymous referees for their detailed comments and suggestions. ∗ Corresponding author. E-mail addresses: [email protected] (H. Fujimoto), [email protected] (E.-S. Park). 1053-5357/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.socec.2010.03.002
and Vesterlund also find women tend to care more about equalizing payoffs. See Eckel and Grossman (2008) for a comprehensive review of works on differences between genders. In this paper, we take a look at gender differences in the context of voluntary public good provision under the two different framing conditions—a positive frame and a negative frame following Andreoni (1995). In order to examine the effects of framing on the level of cooperation in public goods experiments, Andreoni considers two different framing conditions: (1) a positive-frame condition, in which a subject’s choice is framed as contributing to a public good that makes other subjects better off and (2) a negative-frame condition, in which a subject’s choice is framed as buying a private good that makes other subjects worse off. By conducting public goods experiments under these two conditions, Andreoni finds that contribution rates are considerably lower under the negative frame condition than under the positive frame condition. Park (2000) extends Andreoni’s framing experiment to combine social psychologists’ value orientation tests with public goods experiments. He finds that there are systematic differences in framing effects across subjects with different value orientations. The main objective of this paper is to examine whether there are systematic gender differences in each of the framing conditions. The major finding of this experiment is that while there is no significant gender difference in subjects’ contribution rates under the positive-frame, there is a significant gender difference in their contribution rates under the negative-frame. In particular, women are more generous in their contribution than men under the negative-
456
H. Fujimoto, E.-S. Park / The Journal of Socio-Economics 39 (2010) 455–457
frame. Section 2 explains the experimental design and Section 3 presents the results of the experiments. 2. Experimental design 120 subjects participated in each framing condition, for a total of 240 subjects—101 female students (48 in the positive frame and 53 in the negative frame) and 139 male students (72 in the positive frame and 67 in the negative frame). All subjects were volunteers from large introductory microeconomics classes at Missouri University of Science and Technology over three semesters. The data were collected in 6 separate sessions. For each session, 40 subjects were recruited and divided randomly into two rooms of 20 each. A positive-frame experiment was conducted in one room, while a negative-frame experiment was conducted in the other room. Instructions that are nearly identical to the one used in Andreoni’s experiment (Andreoni, 1995, pp. 14–19) were used.1 The subjects were given instructions and an ‘Investment Decision Form’, which subjects used to record their decisions to allocate 60 tokens between an Individual Exchange Account and a Group Exchange Account. Our experiments closely followed that of Andreoni (1995) and the following discussion is based on Andreoni (1995, pp. 4–6): subjects played in groups of five. Each subject was given 60 tokens. In the positive-frame, every token placed in the private good xi (Individual Exchange) earns one token for subject i, while every token given to the public good gi (Group Exchange) earns one half for all five group members. (One token is worth ten cents.) Thus, subject i’s problem is to maximize i = xi +
1 1 gj gi + 2 2
(1)
j= / i
subject to the budget constraint xi + gi = 60. Thus, in this positiveframe, action of contributing to the public good would generate a positive externality for other subjects. The positive-frame instructions to subjects included “Every token you invest in the Individual Exchange will yield you a return of one. Every token invested in the Group Exchange will yield of one half for every member of the group, not just the person who invested it. It does not matter who invest tokens in the Group Exchange. Everyone will get a return from every token invested—whether they invest in the group or not.” In the negative-frame, an investment in the private good was presented as making others worse off. That is, the above positive frame can be converted into the negative frame by substituting the budget constraint of the other players, xj + gj = 60 into the objective function (1): 1 1 (60 − xj ) gi + 2 2
i
= xi +
i
1 1 = xi + gi − xj + 120. 2 2
j= / i
j= / i
This negative frame was expressed in the negative frame instructions to the subjects in the following way: “Every token you invest in the Individual Exchange will yield you a return of one. However, each token you invest in the Individual Exchange will reduce the earnings of the other players by one half each. . .. It will also be true that when the other members of your group invest in the Individual Exchange, then your earnings will be reduced by 1/2 times their investment in the Individual Exchange. . .. Every token you invest in the Group Exchange will yield a return of 1/2 for you.”
1
Instructions are available at http://www.mst.edu/ espark/frame inst.pdf.
Table 1 Framing effects. Contribution percentage
Difference at 5% level
Male
Positive-frame (52.2%) Negative-frame (23.6%)
Significant (t = 6.105; p = 0.0000)
Female
Positive-frame (49.2%) Negative-frame (34.2%)
Significant (t = 2.507; p = 0.0139)
Also, in order to provide the same incentive for the subjects under the two different frames, each subject received automatic earnings of 120 tokens to assure that the two conditions are mathematically equivalent. Unlike Andreoni’s experiment, the subjects played the game only once. This is to minimize any possible strategic and/or learning behavior. Two experimenters, one male and one female, conducted each conditioned experiment. Upon students returning the Investment Decision Form, the experimenters calculated and prepared an ‘earnings report’ for each subject. As students exit the room, they were paid privately. In order to avoid any possible “in-group” effects, no explicit or implicit emphasis on gender either during recruiting or running the experiment was made. This is different from some of the earlier experiments that compared all-male with all-female groups. 3. Results and discussions Contribution rates to the public good of all subjects (both male and female) under the positive-frame and under the negativeframe were 51.0% and 28.3%, respectively and there is a significant difference between the two rates (t = 6.108). These results are in line with findings of previous experiments (Andreoni, 1995; Park, 2000) and seem to be consistent with general findings in psychology that if the consequences of their action are positive, people feel much happier from having taken action than if the consequences are negative and the same result occurs. That is, it seems that people enjoy doing a good deed more than they enjoy not doing a bad did. As Andreoni put it aptly, the strength of the warm-glow from doing good exceeds that of the cold-prickle from doing bad. We now separate the framing effects for each gender, which is summarized in Table 1: contribution percentage of male subjects in the positive-frame and in the negative-frame are 52.2% and 23.6%, respectively and the difference is statistically significant (t = 6.105; p = 1.06 × 10−8 ). Also, contribution rates of female subjects in the two treatments are 49.2% and 34.2%, respectively, which are significantly different at the 5% level (t = 2.507; p = 0.0139). Thus, the framing effects are significant for both men and women. (Mann–Whiteny rank-sum nonparametric tests confirm qualitatively the same result.) We next look at gender differences in contribution rates while controlling for frame for each treatment. Table 2 summarizes the findings. Under the positive-frame the average contribution rate of male subjects is slightly higher than that of female subjects (52.2% and 49.2%, respectively), but there is no statistically significant difference between the two (t = 0.496). On the other hand, under the negative-frame, female subjects contributed to the public good about 45% more than male subjects and the gender difference Table 2 Gender differences in each framing condition. Contribution percentage
Difference at 5% level
Positive-frame
Male (52.2%) Female (49.2%)
Insignificant (t = 0.496)
Negative-frame
Male (23.6%) Female (34.2%)
Significant (t = 2.242; p = 0.0270)
H. Fujimoto, E.-S. Park / The Journal of Socio-Economics 39 (2010) 455–457
is statistically significant at the 5% level (t = 2.242; p = 0.0270). Thus, while there is no gender difference under the positive-frame, there is a significant gender difference under the negative-frame. (Mann–Whiteny rank-sum nonparametric tests yield qualitatively the same result.) It is rather difficult to make direct and meaningful comparisons of our results with previous public goods experiments because our experimental design is quite different from others. Instead, we make a couple of general observations regarding gender effects in each frame: first, our results do not seem to be very far off from the findings of Andreoni and Vesterlund (2001), who confirm general findings in psychology that some men are selfish and some men are altruists, while women are in general more concerned with fairness than men and tend to share evenly. In the two different frame conditions of our experiments, male subjects exhibited more contrasting contribution rates (52.2% versus 23.6%) than female subjects did (49.2% versus 34.2%). Second, our results are related to some studies in psychology that have shown that women are more prone to feel guilt than men (see, for examples, Harvey et al., 1997) and guilt often promotes constructive, other-oriented behavior (see, for example, Tangney, 1991). Andreoni describes the positive-frame as the situation of creating the warm-glow of doing something good and the negative-frame as the situation of creating the cold-prickle of doing something bad. If we are willing to agree that the negative-frame is more “guilt-inducing” than the positive-frame, then women who are more guilt-prone than men will be likely to be more cooperative in the negative-frame, which is what our results reveal. Before closing, we would like to point out some limitations of our results. Recall that in order to focus on the asymmetry between positive and negative externatlities, our experiments were designed to exclude possible learning and strategic behavior that could be observed in repeated settings. It would be an interesting topic for future research to test the extent to which our results are robust to
457
learning and continued contributions (for example, would women sustain the higher levels of contributions than men under the negative-frame even in the repeated settings?). In conclusion, we join other authors who have conducted experiments of gender effects in their general conclusion that gender difference can be an influential factor in various economic outcomes and experimenters may need to take greater care in ensuring the gender balance in their experiments and in particular, in guiltinducing situations. References Andreoni, J., 1995. Warm-glow versus cold-prickle: the effects of positive and negative framing on cooperation in experiments. Quarterly Journal of Economics 110, 1–21. Andreoni, J., Vesterlund, L., 2001. Which is the fair sex? Gender differences in altruism. Quarterly Journal of Economics 116, 293–312. Bolton, G., Katok, E., 1995. Experimental test for gender differences in beneficent behavior. Economics Letters 48, 287–292. Brown-Kruse, J., Hummels, D., 1993. Gender effects in laboratory public goods contribution: do individuals put their money where their mouth is? Journal of Economic Behavior and Organization 22, 255–267. Cadsby, C.B., Maynes, E., 1998. Gender and free riding in a threshold public goods game: experimental evidence. Journal of Economic Behavior and Organization 34, 603–620. Eckel, C., Grossman, P., 1998. Are women less selfish than men? Evidence from dictator experiments. Economic Journal 108, 726–735. Eckel, C., Grossman, P., 2008. Differences in the economic decisions of men and women: experimental evidence. In: Plott, C., Smith, V. (Eds.), Handbook of Experimental Results. Elsevier, New York, pp. 509–518. Harvey, O.J., Gore, E.J., Frank, H., Batres, A.R., 1997. Relationship of shame and guilt to gender and parenting practices. Personality and Individual Differences 23, 135–146. Nowell, C., Tinkler, S., 1994. The influence of gender in the provision of a public good. Journal of Economic Behavior and Organization 25, 25–36. Park, E.S., 2000. Warm-glow versus cold-prickle: a further experimental study of framing effects on free-riding. Journal of Economic Behavior and Organization 43, 405–421. Tangney, J.P., 1991. Moral affect: the good, the bad, and the ugly. Journal of Personality and Social Psychology 61, 598–607.