Supplemental Materials

“Paying More for Others” By M. H. Jung et al., 2014, Journal of Personality and Social Psychology http://dx.doi.org/10.1037/a0037345

Table of Contents 1. Table S1.1. Skewness of Payment Amount in Studies 1-4 3 2. Table S1.2. Payment Amounts in Studies 1–4 3 3. Table S1.3 Log Transformation of Payments in Studies 1-4 4 4. Table S2. List of Collected Measures on a 1–7 Likert-Scale in Studies 5–8 5

5. Table S3. Skewness of Payment Amounts in Studies 5–8 6 6. Table S4. Exclusions of Participants and Log-Transformed Payment Amounts in Study 5 6 7. Table S5.1. Mean Payment Amounts (Sample Size, Standard Deviation) in Study 6 8 8. Table S5.2. Analysis of Variance in Study 6 8 9. Table S6.1. Average Payment Amounts (Sample Size, Standard Deviation) in Study 7 9 10. Table S6.2. Analysis of Variance in Study 7 9 11. Table S7.1. Mean Payment Amounts (Sample Size, Standard Deviation) in Study 8 10 12. Table S7.2. Analysis of Variance in Study 8 10 13. Table S8.1. Means and Standard Deviations of Willingness-to-Pay for Self and Other in Study 9A 11 14. Table S8.2. Number and Percentage of Participants Who Believed That They and Others Could Pay Any Price in Study 9A 12 Supplemental Materials for “Paying More for Others”2

15. Table S8.3. Means and Standard Deviations of Willingness-to-Pay for Self and Other in Study 9B 12 16. Table S8.4. Number and Percentage of Participants Who Believed That They and Others Could Pay Any Price in Study 9B 13 17. Table S8.5. Means and Standard Deviations of Willingness-to-Pay for Self and Other in Study 9C 14 18. Table S8.6. Number and Percentage of Participants Who Believed That They and Others Could Pay Any Price in Study 9C 15 19. Figure S1.1. Card Used in the Message Condition in Study 6 16 20. Figure S1.2. Card Used in the Payment Reporting Condition in Study 6 17 21. Figure S1.3. Card Used in the Message and Payment Reporting Condition in Study 6 18 Supplemental Materials for “Paying More for Others3”

Table S1.1 Studies 1–4: Skewness (and Standard Error) of Payment Amounts Study Group level Individual level Average payment skewedness Log10 (average payment + 1) skewness Payment skewedness Log10 (payment +1) skewness 1 1.354 (0.197) 0.222 (0.197) 0.849 (0.138) 0.087 (0.138) 2 0.933 (0.197) 0.057 (0.197) 1.264 (0.130) 0.096 (0.130) 3 1.081 (0.140) 0234 (0.140) 1.537 (0.103) 0.125 (0.103) 4 0.610 (0.211) 0.748 (0.211) 0.432 (0.185) 0.854 (0.185) Supplemental Materials for “Paying More for Others4”

Table S1.2 Studies 1–4: Mean Payment Amounts

Stud Payment per person per group Payment per person y Average Average controlling for group size Average Average controlling for group size

1 MPIF = $2.67 vs. MPWYW = $1.82 MPIF = $2.63 vs. MPWYW = $1.86 MPIF = $3.12 vs. MPWYW = $1.89 MPIF = $2.84 vs. MPWYW = $2.14 F(1, 149) = 4.74, p=.031 F(1, 148) = 4.06, p = .046 F(1, 309) = 18.32, p < .001 F(1, 308) = 6.65, p = .010 2 MPIF = $3.07 vs. MPWYW = $2.19 MPIF = $3.16 vs. MPWYW = $2.09 MPIF = $2.64 vs. MPWYW = $1.84 MPIF = $2.70 vs. MPWYW = $1.78 F(1, 150) = 5.33, p = .022 F(1, 149) = 8.26, p = .005 F(1, 351) = 6.79, p = .001 F(1, 350) = 18.85, p < .001 3 MPIF = $3.59 vs.MPWYW = $2.64 MPIF = $3.56 vs. MPWYW = $2.66 MPIF=$3.20 vs. MPWYW=$2.50 MPIF=$3.15 vs. MPWYW = $2.54 F(1, 302) = 10.33, p = .001 F(1, 301) = 9.55, p =.002 F(1, 556) = 11.45, p=.001 F(1, 555) = 8.77, p = 0.003 4 MPIF = $2.33 vs. MPWYW = $1.93 MPIF = $2.33 vs. MPWYW = $1.93 MPIF = $2.36 vs. MPWYW = $1.90 MPIF=$2.36 vs. MPWYW=$1.90 F(1, 130)=6.50, p = .012 F(1, 129) = 6.45, p = .012 F(1, 171) = 12.13, p = .001 F(1, 170) = 11.70, p = .001 Note. M = mean; PIF = pay-it- forward condition; PWYW = pay-what-you-want condition.

Table S1.3 Studies 1-4: Log-Transformed Payment Amounts

Average payment amount per person per Payment amount per person + 1 Study group + 1

Log10 Log10 controlling for group size Log10 Log10 controlling for group size

1 MPIF = MPIF = 0.45 vs. MPWYW = 0.36 MPIF = 0.49 vs. MPIF = 0.44 vs. MPWYW = 0.38 0.45 vs. F(1, 148) = 3.50, p = .064 MPWYW = 0.34 F(1, 308) = 3.05, p = .082 MPWYW = F(1, 309)=14.60, p < 0.35 .001 Supplemental Materials for “Paying More for Others5”

F(1, 149) = 4.21, p = .042 2 MPIF = MPIF = 0.53 vs. MPWYW = 0.40 MPIF = 0.47 vs. MPIF = 0.48 vs. MPWYW = 0.36 0.51 vs. F(1, 149) = 7.24, p = .008 MPWYW = 0.37 F(1, 350) = 8.98, p < .001 MPWYW = F(1, 351) = 7.25, p 0.413 =. 001 F(1, 150) = 4.36 p= .039 3 MPIF = MPIF = 0.56 vs. MPWYW = 0.48 MPIF = 0.47 vs. MPIF = 0.47 vs. MPWYW = 0.53 0.57 vs. F(1, 301) = 6.31, p = .013 MPWYW = 0.53 F(1, 555) = 5.54, p = .019 MPWYW = F(1, 556) = 7.72, p = 0.48 .006 F(1, 302)=6.86 , p=.009 4 MPIF = MPIF = 0.51 vs. MPWYW = 0.43 MPIF = 0.51 vs. MPIF = 0.51 vs. MPWYW = 0.44 0.51 vs. F(1, 129)=7.82, p=.006 MPWYW = 0.44 F(1, 170) = 13.19, p < .001 MPWYW = F(1, 171) = 13.63, p 0.44 < .001 F(1, 130) = 7.88, p = .006 Note. M = mean; PIF = pay-it- forward condition; PWYW = pay-what-you-want condition.

Table S2 Studies 5–8: List of Collected Measures on a 1–7 Likert-Scale Supplemental Materials for “Paying More for Others6”

Questions Posed After participating in unrelated survey but before the pricing manipulation: 1. How much have you enjoyed your experience at UCB? 2. How much do you like participating in academic research? 3. To what extent do you feel that you are a generous person? 4. To what extent do you think that you have more or less money than an average UCB student? After the pricing manipulation (after paying for a coffee mug): 1. How much money do you predict that the next participant would pay for a mug? 2. How much do you think that the participant before you had paid for a mug? 3. How much do you think is the price of the same mug in the UCB bookstore? 4. To what extent did the following factors (a–k) influence your decision on the amount of your payment? a. Support of an academic research project b. Color of the mug c. Novelty of this experiment d. $10 payment e. Average price of a mug f. Expectation by the experimenter g. Value of the Cal logo/UCB affiliation h. Cost of manufacturing a mug (only in Study 7) i. Amount of money the previous participant paid for a mug (only in Study 7—participants who were not informed about the previous participant’s payment were asked) j. The participant who will participate after me (only in Study 7) k. The participant who participated before me (only in Study 7) 5. How many mugs do you own? 6. How often do you use a mug? 7. How satisfied are you with the mug? (only in Studies 5, 6, and 8) 8. How satisfied are you with this consumer behavior study experience? (only in Studies 5, 6, and 8) 9. To what extent do you feel that your payment was fair? 10. To what extent do you feel that the previous participant’s payment was fair? (In Study 7 only—participants who were told about the previous participant’s payment were asked.) 11. Please list other factors, if any, that influenced your decision on the amount of your payment. 12. Please provide age, gender, and ethnicity Supplemental Materials for “Paying More for Others7”

Note. Likert scale ratings: 1 = not much at all; 4 = neutral; 7 = very much. UCB = University of California, Berkeley. Table S3 Studies 5–8: Skewness of the Average Payment Amounts

Study Payment skewedness (SE) Log10 (payment +1) skewedness (SE) 5 1.870 (0.144) 0.249 (0.144) 6 1.587 (0.175) 0.227 (0.175) 7 2.399 (0.173) 0.171 (0.173) 8 2.396 (0.135) 0.119 (0.135)

Table S4 Study 5: Exclusions of Participants and Analysis of Variance

Excluding Dependent variable: Payment Dependent variable: Log10 (payment + 1) None Main effects: Main effects: Pricing: F(1, 288) = 5.47, p = .020 Pricing: F(1, 288) = 2.80, p = .096 Social exchange: F(2, 288) = 0.76, p = .469 Social exchange: F(2, 288) = 0.15, p = .862

Interaction effect: Interaction effect: F(2, 288) = 0.13, p =.882 F(2, 288) = 0.04, p =.963 Three who knew the confederate Main effects: Main effects: Pricing: F(1, 285) = 5.97, p = .015 Pricing: F(1, 285) = 3.30, p = .070 Social exchange: F(2, 285) = 0.82, p = .441 Social exchange: F(2, 285) = 0.15, p = .860

Interaction effect: Interaction effect: F(2, 285) = 0.17, p =.846 F(2, 285) = 0.01, p =.990 Three who knew the confederate and Main effects: Main effects: two who were inebriated Pricing: F(1, 283) = 6.06, p = .014 Pricing: F(1, 283) = 3.36, p = .068 Social exchange: F(2, 283) = 0.90, p = .410 Social exchange: F(2, 283) = 0.19, p = .824

Interaction effect: Interaction effect: F(2, 283) = 0.18, p =.836 F(2, 283) = 0.01, p =.990 Three who knew the confederate, Main effects: Main effects: two who were inebriated, and one Pricing: F(1, 282) = 6.39, p = .012 Pricing: F(1, 283) = 3.67, p = .056 who learned about the study from a Social exchange: F(2, 282) = 0.96, p = .385 Social exchange: F(2, 283) = 0.24, p = .780 friend Interaction effect: Interaction effect: F(2, 282) = 0.22, p =.803 F(2, 283) = 0.02, p =.981 Three who knew the confederate, Main effects: Main effects: two who were inebriated, one who Pricing: F(1, 276) = 6.03, p = .015 Pricing: F(1, 276) = 3.50, p = .063 learned about the study from a Social exchange: F(2, 276) = 0.78, p = .459 Social exchange: F(2, 276) = 0.19, p = .829 friend, and six who knew the experimenter Interaction effect: Interaction effect: F(2, 276) = 0.21, p =.810 F(2, 276) = 0.03, p =.973

Table S5.1 Study 6: Mean Payment Amounts (Sample Size; Standard Deviation)

Message left Payment not shown Payment shown No $1.13 (n = 48; 1.33) $2.14 (n = 48; 1.98) Yes $1.96 (n = 52; 2.62) $2.54 (n = 45; 2.24)

Table S5.2 Study 6: Analysis of Variance

Dependent variable: Payment Dependent variable: Log10 (payment +1) Main effects: Main effects: Payment reporting: F(1, 189) = 6.86, p = .010 Payment reporting: F(1, 189) = 11.04, p = .001 Message: F(1, 189) = 4.12, p = .044 Message: F(1, 189) = 1.83, p = .178

Interaction effect: Interaction effect: F(1, 189) = 0.52, p =.470 F(1, 189) = 0.42, p =.518

Table S6.1 Study 7: Mean Payment Amounts (Sample Size; Standard Deviation) Information of other’s payment Condition No Yes Pay-what-you-want $1.21 (n = 49; 1.47) $1.23 (n = 49; 0.93) Pay-it-forward $2.48 (n = 44; 2.40) $1.19 (n = 56; 0.81)

Table S6.2 Study 7: Analysis of Variance

Dependent variable: Payment amount Dependent variable: Log10(payment amount + 1) Main effects: Main effects: Pricing: F(1, 194) = 8.48, p = .004 Pricing: F(1, 194) = 7.90, p = .005 Information about others’ payment: F(1, 194) = 8.99, p = .003 Information about others’ payment: F(1, 194) = 2.54, p = .113

Interaction effect: Interaction effect: F(1, 194) = 9.66, p =.002 F(1, 194) = 8.11, p =.005

Table S7.1 Study 8: Mean Payment Amounts (Sample Size; Standard Deviation) Condition No information of others’ payment Previous participant paid $0.50 Previous participant paid $2.50 Pay-what-you-want $1.36 (n = 56; 1.20) $1.29 (n = 53; 1.29) $1.76 (n = 56; 1.25) Pay-it-forward $2.56 (n = 53; 2.54) $0.99 (n = 54; 0.84) $1.82 (n = 55; 1.07)

Table S7.2 Study 8: Analysis of Variance

Dependent variable: Payment amount Dependent variable: Log10 (payment amount + 1) Main effects: Main effects: Pricing: F(1, 321) = 3.91, p = .049 Pricing: F(1, 321) = 3.87, p = .050 Information about others’ payment: F(2, 321) = 9.43, p < .001 Information about others’ payment: F(2, 321) = 9.04, p <.001

Interaction effect: Interaction effect: F(2, 321) = 7.84, p < .001 F(2, 321) = 5.19, p =.006 Table S8.1 Study 9A: Means (and Standard Deviations) of Willingness to Pay for Self and Other

Condition Willingness to pay: Self and other Pay-what-you-want Pay-it-forward (n = 200) (n = 213) Winsorized at $10 Self $1.96 (2.14) $2.73 (2.38) Other $2.14 (2.30) $2.67 (2.33) Raw Self $2.04 (2.58) $3.34 (5.65) Other $2.22 (2.70) $3.28 (5.65) Natural log (willingness to pay + 1) Self 0.92 (0.55) 1.18 (0.64) Other 0.97 (0.57) 1.18 (0.62) Winsorized at $5 Self $1.69 (1.32) $2.39 (1.55) Other $1.82 (1.42) $2.33 (1.45) Table S8.2 Study 9A: Number and Percentage of Participants Who Believed That They and Others Could Pay Any Price

Individual whom the participants were told could choose any price Condition “Customer before you” “You” “Customer after you” n % n % n % PWYW correct: 168/200 182/200 170/200 % correct answer in PWYW 84.00% 91% 85% PIF correct: 182/211 186/211 177/211 % correct answer in PIF 86.26% 88.15% 83.89% Total correct answer 350/411 368/411 347/411 % correct answer 85.16% 89.53% 84.42% Note. PWYW = pay what you want; PIF = pay it forward.

Table S8.3 Study 9B: Means (and Standard Deviation) of Willingness to Pay for Self and Other

Pay what you want Pay it forward Willingness to pay Can (n = 196) Chance (n = 186) Can (n = 185) Chance (n =189) Winsorized at $10 Self $1.68(1.36) $1.81 (1.52) $2.55 (1.68) $2.12 (1.59) Other $1.70 (1.37) $1.92 (1.50) $2.43 (1.29) $2.45 (1.59) Raw Self $1.68 (1.36) $3.10 (18.26) $57.63 (749.74) $2.53 (2.22) Other $1.69(1.37) $3.48 (21.90) $3.18 (10.94) $2.27 (1.28) Natural log (willingness to pay + 1) Self $0.88 (0.43) $0.94 (0.56) $1.21 (0.74) $1.15 (0.45) Other $0.90 (0.42) $0.98 (0.56) $1.16 (0.48) $1.11 (0.38) Winsorized at $5 Self $1.63 (1.19) $1.74 (1.28) $2.45 (1.39) $2.37 (1.36) Other $1.65 (1.17) $1.87 (1.32) $2.36 (1.27) $2.26 (1.25)

Table S8.4 Study 9B: Number and Percentage of Participants Who Believed That They and Others Could Pay Any Price

Individual whom the participants were told could choose any price Condition “You” “Customer after you” % n % n % PWYW “can” correct: 194/196 194/196 % correct answer in PWYW “can” 96.94% 98.98% 98.98% PWYW “chance” correct” 181/186 183/186 % correct answer in PWYW “chance” 97.85% 97.31% 98.39% PIF “can” correct 176/185 177/185 ….% correct answer in PIF “can” 95.14% 95.14% 95.68% PIF “chance” correct 185/189 186/189 ….% correct answer in PIF “chance” 93.65% 97.88% 98.41% Total correct answer 736/756 740/756 ….% correct answer 95.90% 97.35% 97.88% Note. PWYW =pay what you want; PIF = pay it forward. Table S8.5 Study 9C: Means (and Standard Deviations) of Willingness to Pay for Self and Other

PIF PWYW Willingness to pay PIF Company (n (n = 174) Singular (n = 176) Plural (n = 181) (n = 206) = 159) Winsorized at $10 Self $1.67 (1.51) $2.27 (1.78) $2.33(1.70) $2.46(1.69) $2.30 (1.84) Other $1.70 (1.43) $2.13 (2.27) $2.24 (1.64) $2.38 (1.64) $2.24 (1.70) Raw Self $1.67 (1.51) $2.58 (4.44) $2.54 (3.41) $2.77 (4.43) $2.55 (3.78) Other $1.70 (1.47) $2.50 (5.19) $2.27 (1.83) $2.69(4.22) $2.71(5.28) Natural log (willingness to pay + 1) Self 0.88 (0.43) 1.08 (0.51) 1.11 (0.49) 1.15 (0.50) 1.08 (0.52) Other 0.90 (0.42) 1.10 (0.48) 1.08 (0.45) 1.14 (0.49) 1.09 (0.51) Winsorized at $5 Self $1.58 (1.15) $2.12 (1.29) $2.22 (1.32) $2.34 (1.31) $2.16 (1.42) Other $1.64 (1.17) $2.00 (1.93) $2.15 (1.33) $2.28 (1.29) $2.10 (1.23) Note. PWYW = pay what you want; PIF = pay it forward. Table S8.6 Study 9C: Number and Percentage of Participants Who Believed That They and Others Could Pay Any Price

Individual whom the participants were told could choose any price Condition “You” “Customer after you” % n % n % PWYW correct: 170/174 168/174 % correct answer in PWYW 93.68% 97.70% 97.00% PIF correct 198/206 193/206 ….% correct answer in PIF 93.20% 96.12% 93.69% PIF singular correct 146/153 148/159 ….% correct answer in PIF 93.08% 95.42% 93.08% PIF plural correct 164/176 165/176 ….% correct answer in PIF 94.32% 93.18% 93.75% PIF company correct 169/181 159/181 ….% correct answer in PIF 87.85% 93.37% 87.85% Total correct answer 847/896 833/896 ….% correct answer 93.53% 94.53% 92.97% Figure S1.1. Card Used in the Message Condition in Study 6

Figure S1.2. Card Used in the Payment Reporting Condition in Study 6

Figure S1.3. Card Used in the Message and Payment Reporting Condition in Study 6