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1. Who can I trust in the P2P Noosphere? does Jeremy Goslin School of Psychology University of Plymouth … make you nice?

2. Gettingbeyondtit-for-tat.. • Enforced altruism • Expensive • Circumvention • Social Networks? • Social relationships can improve trust • Increase cooperation/altruism • P2P • Tribler • e.g. cooperative download 

3. Group Identity • Social Identity Theory (Billig & Taijfel, 1973) • In-group members treated more positively than out-group members • Self-identity partly derived from group identity • Motivated to enhance positive group distinctiveness • Or seek out alternative groups that are more positively distinct • Profound effects on social strategies • Group membership tends to lead to within group altruism • Expectation of reciprocation • Communication not required • Group membership can be ad-hoc

4. How can P2P benefit from Social Identity? • Question: Do groups need to be extrinsic? • Can self defined dynamic groups lead to the same effect, or better? • Question: What are the optimum group-conditions? • Maximal peer cooperation • Psychology experiments for P2P: • Control of information, communication, interaction • Endogenous vs. exogenous groups • Information • Group vs. Individual information • Reputation (over time) • Group Entry • Tags (Subsuming action to the group) • Voting

5. Experimental Paradigm • Game theory • The study of conflict between thoughtful and potentially deceitful opponents • Assumptions: • Rationality • Maximisation of individual gain • Provides robust basis for behavioural experimentation • Already know what rational players should do • Nash equilibrium point • Why don’t players act rationally? • What are the conditions for optimum irrationality? • Game for experiments • n-Persons iterated Prisoner’s Dilemma

6. Experiment Game Moreover, whilst the college will initially assign you to a group, the university allows students to change groups whenever they like, and even to set up new groups. … What you decide to do is up to you, but finding the right group is likely to be the key to getting good marks whatever you choose. • Computer mediated multiplayer text-based game • Scenario • Students involved in group projects • Maximise course credits: • Fully contribute to group assignment (cooperate) • Concentrate on individual work (defect) • Information • Themselves and a ‘friend’ • Decision • Reward • Fortune • Groups • Interaction within group • Group movement: • Stay within group • New group • Join ‘friend’ For next week you have the chance to start a new group, to join the group of your friend, or stay in your current group. Press space to continue in your current group Press N to go to a new group Press F to join the same group as your friend You have just enrolled on a new degree course in social studies at the College of Princeton. This course in very progressive, they believe that to study sociology the students must gain a direct and first hand experience of working with others. To this end half of the course credits required by the degree are for group assignments, and only half assigned to individual study. However, as Princeton standards are very high they will only let the best students graduate each year, and you know that competition for course credits is fierce. You need good marks on both your individual and group assignments, which are averaged out each week. Each week you have to decide whether you want to focus on getting high marks your individual assignment, at the cost of putting less time into your group assignment. However if lots of people in your group also decide to do this then the group mark will be lower, and your grade average for that week will suffer. On the other hand, if everyone contributes fully to the group assignment then that part of the marks will be high, and may compensate you for the time lost on the individual assignment. You chose to make a full contribution to the group assignment and managed to earn 6 between your individual and group assignments this week. Thus far you have earned 18 course credits. This week your have heard that a friend managed to receive 10 course credits after they concentrated on their individual assignment, they now have a total of 26 credits.

7. Experiment 1: Endogenous vs. Exogenous Groups • Question: Does inter-group movement improve cooperation? • Condition 1: Game of two fixed groups • No inter-group interaction • Condition 2: Dynamic inter-group movement • Two initial groups • Every round players may either: • Stay in their group • Move to group of a ‘friend’ • Set up a new group • Comparison: System wide proportion of cooperation between conditions • Fixed time frame (first 20 game rounds)

8. Experiment 1: Results * * * First 20 rounds of play Proportion of Co-operation fixed groups n=62 dynamic groups n=71 illusory groups n=74 • Cooperationeffect of dynamic groups • psychological • structural • Illusory group condition • Interaction as no group condition

9. Experiment 1: Summary • Question:Does inter-group movement improve cooperation? • Freedom of movement between groups improves systemic cooperation • Even if the groups have no actual effect over interaction • How to reduce the prevalence of freeriders raiding cooperative groups? • Ejection from groups? • Entry restrictions?

10. Tags (e.g. Hales, 2000) Shared tags (group) Game Interactions Mutation of tag Copy tag and strategy • Evolutionary computer models • very simple agents that evolve (replication/mutation) based on payoff • “tag” code strategy and group membership • Basic Cooperation process • Initial random groups • Groups containing defectors get smaller as agents leave them for better groups or form new groups • Basic Cooperation process • Defectors quickly surrounded by other defectors because new entrants to group copy their behaviour • Hence defection not sustainable strategy => it destroys your own groups cooperation • Dynamical process with groups constantly forming and dissipating but maintain high cooperation

11. Experiment 2: Group info and tags movement • Questions: • How does the provision of group information affect cooperation? • Can ‘tags’ based group movement improve cooperation over free movement in endogenous groups? • Condition 1: Group information • Number and ratio of cooperators and defectors within group • Rewards for cooperation and defection • Condition 2: Tags • Initial cooperate/defect decision (round 1) • Decision carried forward to subsequent rounds • 10% chance each round of changing decision • To move groups you must take on game decision of your ‘friend’

12. Experiment 2: Results *  * * * First 20 rounds of play Proportion of Co-operation fixed groups n=62 dynamic groups n=71 illusory groups n=74 group info n=40 Tags + group info n=40 Tags - group info n=35 • Tags • Initial choice of action (co-operate / defect) • Thereafter probability of change = 0.1 per round • Moving groups • Copy game decision of compatriot • Include group information • Proportion of co-operators and defectors • Co-operator and defector rewards

13. Experiment 2: Summary • Question: How does the provision of group information affect cooperation? • Group information provides excellent source of information on the best cooperative groups • for defectors and cooperators • Defectors more pro-active so ‘raiding’ results in reduced systemic cooperation • Question: Can ‘tags’ based group movement improve cooperation over free movement in endogenous groups? • Trading decisions for group membership does increase cooperation? • Possible effect of the reduction of decision ‘churn’ • Can simplistic voting match this strategy?

14. Experiment 3: Voting and reputation • Questions: • Can group members protect themselves from defectors voting to bar them entry? • How does longer term ‘reputation’ influence voting decisions? • Condition 1: Friend voting on group entry • ‘Friend’ votes to let new members join group • Information on previous decision and reward • Condition 2: Reputation • ‘Friends’ given information on the proportion of cooperation/defection decisions on previous 5 rounds

15. Experiment 3: Results * *   First 20 rounds of play  Proportion of Co-operation dynamic groups n=71 Reputation n=37 Reputation and voting n=32 Voting n=47 illusory voting n=43 • Long-term reputation has no effect on cooperation • With or without voting • Voting to group entry increases cooperation • psychological • Structural • Illusory voting condition • No difference in cooperation to no-voting condition

16. Experiment 3: Analysis of voting • In authentic voting conditions: • 176 attempts to move group • From 1440 group decisions (12%) • 64% were successful • Cooperative voters: • Rejected prospective cooperator: 5.5% • Rejected prospective defector: 18.9% • Defector voters: • Rejected prospective cooperator: 42.8% • Rejected prospective defector: 70.3% • Defectors as wolves turned sheepdogs? • Protecting their ‘herd’ of co-operative sheep

17. Experiment 3: Voting and reputation • Question:Can group members protect themselves from defectors voting to bar them entry? • The action of voting does improve systemic cooperation • No psychological effect of being ‘judged’ • Defectors protecting themselves better than cooperators • Question: How does longer term ‘reputation’ influence voting decisions? • No effect • With complete anonymity and no control over the selection of interactions long term reputation is not important – no long term relationship

18. Conclusions Exploring social freedom for social P2P • Movement • Endogenous groups significantly increase cooperation • But so does the illusion of groups • Information • Group information significantly undermines beneficial group dynamics • Too much information can be a bad thing • Reputation is moot with anonymous and ephemeral relationships • Action • Restriction of choice can be socially beneficial • Subsuming freedom of choice to others for group inclusion (Tags) • Voters can be your friends • Even if they are the enemy