1. Jens Riegelsberger 1 M. Angela Sasse John D. McCarthy 2 November 2006 University College London Human-Centred Systems Group Department of Computer Science A Framework for Trust Applied to Social Computing Current affiliations: 1 Google UK, 2 LBI UK

2. Trust Research in HCI > Trust has gained prominence in HCI research >Trust in web sites (e-commerce: Egger, Sapient, Corritore et al.) >Trust in humans (virtual teams, online advice: Olson et al., Swerts et al.) >… Trust in ambient technologies (CHI 04 Workshop)

3. Dis-embedding Interaction is stretched over time and space and involves complex socio- technical systems [Giddens, 1990] … pervasive in modern societies (e.g. catalogue shopping) ‘Lack of Trust’ online More risk > Privacy (more data required) > Security (open system) > Own errors … More uncertainty > Inexperienced with decoding cues > Less surface cues are available > Cues might have no significance (“anyone could set up a good-looking site”) Symbols vs. Symptoms

4. Relevance of Trust Research > Trust is of high importance for individuals and society > Mediating interactions can result in lower trust (widely publicised ‘lack of trust’ online) > Effect may be partially due to lack of familiarity, … > but trust is an ongoing concern in mediated interactions: Lack of central control More explicit information required Decreased number of trust signals

5. Trust Background > Only required in the presence of risk and uncertainty > “… willingness to be vulnerable based on positive expectations about the actions of others” [e.g. Rousseau et al., 1998; Corritore et al., 2001] > Based on assessment of ability and motivation [Deutsch, 1956] > Assessment can result in cognitive trust [Lahno, 2002, Lewis & Weigert 1985] > But human trust-decisions are also based on immediate pre-rational affective reactions [Corritore et al., 2000, Lewis & Weigert 1985]

6. TRUSTEETRUSTOR

7. 1 Signals TRUSTEETRUSTOR

8. 1 Signals TRUSTEETRUSTOR Separation in Space + UNCERTAINTY

9. Outside Option 1 Signals TRUSTEETRUSTOR 2a Trusting Action 2b Withdrawal RISK Separation in Space + UNCERTAINTY

10. Outside Option 1 Signals TRUSTEETRUSTOR 2a Trusting Action 2b Withdrawal 3a Fulfilment 3b Defection RISK Separation in Space + UNCERTAINTY

11. Outside Option 1 Signals TRUSTEETRUSTOR 2a Trusting Action 2b Withdrawal 3a Fulfilment 3b Defection RISK Separation in Time + UNCERTAINTY Separation in Space + UNCERTAINTY

12. Current HCI Trust Research > Focused on increasing trust (overcoming ‘lack of trust’) >… but well-placed trust is of high importance for long-term acceptance > Largely concerned with cognitive trust >… but trust is also based on affective reactions to interpersonal cues > No coherent theoretical foundation > Measurement often based on self-reports and Prisoner’s Dilemma studies

13. Framework for Trust > 1. Step: Focus on incentives for trustworthy behavior > 2. Step: Identify signals >> Design guidelines for systems that allow well-placed trust > Draws on work by >> Bacharach & Gambetta (Dept. of Sociology, Oxford) >> Raub et al. (ISCORE, Utrecht) > Why should a trustee ever fulfill? > Intrinsic and Contextual Properties >> …. support trustworthy action >> …. signal trustworthiness

14. Outside Option 1 Signals TRUSTEETRUSTOR 2a Trusting Action 2b Withdrawal 3a Fulfilment 3b Defection RISK Separation in Time + UNCERTAINTY Separation in Space + UNCERTAINTY

15. TRUSTEETRUSTOR

16. TRUSTEE Temporal Institutional Social Contextual Incentives Trust Context SignalIncentive Contextual Properties

17. TRUSTORTRUSTEE Temporal Institutional Social Contextual Incentives Trust Intrinsic Properties Context SignalIncentive Intrinsic Properties

18. TRUSTORTRUSTEE Temporal Institutional Social Contextual Incentives Trust Ability Context SignalIncentive Intrinsic Properties Internalised Norms Benevolence

19. Types of Trust

20. TRUSTORTRUSTEE > Expectation of future encounters is an incentive for trustworthy behaviour > A defrauded trustor might withdraw from future interactions or retaliate > Past experience gives information about trustor’s personal properties Requirements Stable identities, traceability of outcomes to actors and actions Contextual Incentives Trust Costs Benefits Intrinsic Properties Benevolence, Internalised Norms Temporal Social Institutional

21. TRUSTORTRUSTEE > Trustors share information about trustees’ past behaviour in the form of reputation > Reputation is a ‘hostage’ in the trustor’s hand Requirements > Reliable & unbiased reputation aggregation > Incentives for contributing reputation information > Shared understanding of cooperation & defection Contextual Incentives Trust Costs Benefits Intrinsic Properties Benevolence, Internalised Norms, Ability Social Temporal Social Institutional

22. TRUSTORTRUSTEE > Law, Contracts Requirements: > A priori definitions … little flexibility > Low cost of investigation and punishment compared to risk > Organisations, brands > Trust is vested in roles rather than individuals Requirements: > Clear and reliable signs of institutional affiliation Contextual Incentives Trust Costs Benefits Intrinisc Properties Benevolence, Internalised Norms, Ability Institutional Temporal Social Institutional

23. Questions of trust in social networking sites > The site as trustee >Respect for privacy (no selling on of personal information, no spam) >Ability to keep personal data secure >Stay in business (to make initial effort of registering worthwhile) > Other users / people as trustees >Respect for boundaries of context >Respect for norms of conduct

24. USERSITE Institutional Legal systems Consumer protection agencies Temporal Interest in repeat business Depending on presence of alternative trustees Social Depending on presence of alternative trustees Contextual Incentives Trust Costs Benefits Intrinsic Properties Technical Competence, Corporate ethics Contextual Properties

25. USEROTHER USER Institutional Legal systems Site’s code of conduct Temporal Interest in repeat interaction Social Reputation system Contextual Incentives Trust Costs Benefits Intrinsic Properties Induction into norms of forum Contextual Properties

26. Jens Riegelsberger [jensr@google.com] M. Angela Sasse [a.sasse@cs.ucl.ac.uk] John D. McCarthy [j.mccarthy@lbi.com] http://www.cs.ucl.ac.uk/staff/jriegels University College London Department of Computer Science Trust in Mediated Interactions