Pablo Brañas1 Mari Paz Espinosa2 Jaromir Kovarik2 Paper 1: Altruism and Social Integration Paper 2: Inequity Concerns in Social Networks Pablo Brañas1 Mari Paz Espinosa2 Jaromir Kovarik2 Ramon Cobo Reyes1 Natalia Jimenez1 Giovanni Ponti3 1Universidad de Granada, 2 Universidad del País Vasco, 3 Universidad de Alicante

Main Question Is the prosociality of people - altruism and inequity aversion - related to their position in social structures - centrality?

Motivation I It has been observed that the level of social conerns of individuals is affected by many aspects: Entitlement (List and Cherry, 1999) Social distance (Leider et al., 2006) Framing (Tversky and Kahneman,1981) Anonymity (Hoffman et al., 1994, 1996) …

Motivation I It has been observed that the level of social conerns of individuals is affected by many aspects: here How does the level of generosity depends on social network position?

Motivation II The evolutionary literature argues that social norms coevolves with social networks (Boyd & Richerson, JTB 2002; Marsili et al., PNAS 2004; Nowak, Nature 2006; …) If social norms and social structures indeed coevolve, we should observe some relation between the degree of prosociality of individuals and their network position. here

Altruism and Social Network Experiment 1: Altruism and Social Network

Altruism and Network I 2 stages: Network elicitation Indegree, outdegree, reciprocal degree (local measures of connectivity) Betweenness (global measure) – number of shortest path from two individuals passing through node i (how the removal of node i affects the overall connectivity of the network)

Altruism and Network I 2 stages: Network elicitation Dictator game – divide 10 coins between you and other person 3 treatments: (i) standard dictator game (ii) Friends – network distance = 1 (iii) Framing – “would rely on you”

Altruism and Network II

Altruism and Network III

Altruism and Network IV Are more central individuals more generous? 2 dependent variables: Altruism – dictators’ gifts Selfishness = 1 if the gift is 0 or 1 = 0 otherwise

Altruism and Network V

Altruism and Network V

Altruism and Network VI

Conclusions: (1) Less generous individuals tend to be play a peripheral role in the network (both from local and global perspective). (2) People who do not share are not central and do not share independently of the situation they face.

Inequity Concerns (IC) within Social Networks Experiment 2: Inequity Concerns (IC) within Social Networks

IC and Network I Motivation: solve the “problems” of the previous study Complete network ( larger sample size; 3X) Different sharing rule (rather than pure generosity)

IC and Network II (data from Brañas, Duran, Espinosa, forthcoming in Rationality and Society) 2 stages: Network elicitation (<300 subjects) Inequity Aversion game (n= 169, 2 stages) Stage 1: variation of the Dictator game (S,0) (0,S)

IC and Network II (data from Brañas, Duran, Espinosa, forthcoming in Rationality and Society) 2 stages: Network elicitation (<300 subjects) Inequity Aversion game (n= 169, 2 stages) Stage 2: the Dictator is given a possibility to repair at his cost the created inequality: “How much are you willing to pay for subject who have not received anything to get S as well?”

IC and Network II (data from Brañas, Duran, Espinosa, forthcoming in Rationality and Society) 2 stages: Network elicitation (<300 subjects) Inequity Aversion game (n= 169, 2 stages) 2x2 factorial design: Friends Personal involvement in the divided amount

IC and Network III

IC and Network IV The dependent variable measures the inequity concern of each individual with respect the median willingness to pay to repair the inequality

IC and Network V (1) (2) (3) (4) Indegree .117 (.082) - Outdegree .289 (.097)*** Reciprocal degree .231 (.116)** Betweenness .00034*** (.00013) Gender -.327 (.278) -.395 (.282) -.338 (.281) -.370 (.279) N = 169 ; Gender = 1 for males ; *** 1%, ** 5%, * 10%

Conclusion We reinforce that social embeddedness is an important factor (globally and locally) to determine the degree of prosociality (non-selfishness).

Causality Problem Are people more generous because they are important in their circles, or do they play a prominent role because they are for whatever reason more prosocial? Solution: Experimental design issue on which we already work.