1. Interpersonal Trust Model Ing. Arnoštka Netrvalová DSS - seminar, 8.12.2008

2. 2 Interpersonal trust model Why? Where? What? Trust definition Trust values Trust types Mapping functions Trust representation Personal trust factors Personal trust design Personal trust forming Aggregation and transformation Model behaviour study Personal trust effect Conclusion Fide, sed qui fidas, vide. It is an equal failing to trust everybody, and to trust nobody. [ChangingMinds.org] /33

3. 3 DSS-seminar, 8.12. 2008 WHY? WHERE? Phenomenon of everyday life Internet e-banking – credibility e-commerce – trustworthiness of partners e-service – quality, promptness PC and computing /33 Interpersonal trust model

4. 4 DSS-seminar, 8.12. 2008 WHERE? WHAT? Computing and trust P2P systems – security (working together of nodes) GRID computing – security (reliability of sources, users) AD HOC networks – message integrity (node =server, router, client, malicious nodes, special protocols, cryptographic codes) MAS – security dependability (malicious agent detection, migrating, selection of „the best“ agent, system’s optimization) Semantic web – credibility of sources (machine information collection) /33 Interpersonal trust model

5. 5 DSS-seminar, 8.12. 2008 Trust definition Trust (or symmetrically, distrust) is a particular level of the subjective probability with which an agent will perform a particular action, both before we can monitor such an action (or independently of our capacity of ever to be able to monitor it) and in a context in which it affects our own action.----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Gambetta's definition was derived as a summary of the contributions to the symposium on trust in Cambridge, England, 1988. /33 Interpersonal trust model THE TRUST THE TRUST in an individual is a commitment to an action based on a belief that the future actions of that individual will be make for a good outcome.

6. 6 DSS-seminar, 8.12. 2008 Trust values 1 0. 5  0.025 0 Blind trust High trust Low trust Absolute distrust Ignorance Low distrust High distrust 0.950.70.30.05 /33 Interpersonal trust model

7. 7 DSS-seminar, 8.12. 2008 Trust types personal personal – trust between entity - unilateral - reciprocal phenomenal phenomenal – trust to phenomenon (products of phenomenon) /33 Interpersonal trust model

8. 8 DSS-seminar, 8.12. 2008 Mapping function /33 Interpersonal trust model  non-linear  asymmetrical

9. 9 DSS-seminar, 8.12. 2008 Personal trust description Group of n autonomous individuals X ={x 1, x 2, …, x n } Measure of the interpersonal trust (between two individual x i and x j ) Reciprocal trust: x i →x j and x j →x i [ ] Trust representation (in the group) The interpersonal trust in the group - directed weighted graph vertices - the individuals directed edge with weight - measure of interpersonal trust Complete distrust Complete distrust - edge with zero weight No contact No contact - no edge /33 Interpersonal trust model

10. 10 DSS-seminar, 8.12. 2008 Group trust representation A B C 0.9 0.6 0.8 0.5 /33 Interpersonal trust model Example: Representation of personal trust in three individual’s group (A, B, and C) Trust (adjacency) matrix

11. 11 DSS-seminar, 8.12. 2008 Basic personal trust factors Initial trust  Initial trust – is defined as the initial trust value Reputation  Reputation of an entity - is an expectation of its behavior based on information about the entity’s past behavior within a specific context at a given time Recommendation  Recommendation – is based on expectation given by other entities’ observations by communication Contact  Contact – represents direct trust experience  Disposition  Disposition – acceptation intensity of acquired information /33 Interpersonal trust model

12. 12 DSS-seminar, 8.12. 2008 Personal trust factors representation /33 Interpersonal trust model Initial trust matrix Reputation matrix Contact matrix Recommendation matrix Disposition matrix

13. 13 DSS-seminar, 8.12. 2008 Personal trust design /33 Interpersonal trust model Subject Knowledge Base Communication Reputations Recommendations Trust Evaluation Contacts Disposition Initial trust Group of subjects Context

14. 14 DSS-seminar, 8.12. 2008 Personal trust forming - personal trust i-th entity to j-th entity - number of reciprocal contacts i-th and j-th entities - number of recommendations of j-th entity to i-th from others - reputation of j-th entity at i-th entity - randomness, where 0≤  <  1 0  1 1 /33 Interpersonal trust model

15. 15 DSS-seminar, 8.12. 2008 - weight (effect) of reputation (constant / number of steps) - weight (sum of contacts of i-th subject) - weight (sum of recommendations of j-th subject to i-th one Personal trust forming /33 Interpersonal trust model

16. 16 DSS-seminar, 8.12. 2008 Aggregation function /33 Interpersonal trust model

17. 17 DSS-seminar, 8.12. 2008 Transformation – logistic S-curve Interpersonal trust model /33 Transformation  bounded interval  0, 1  Option: min, max  weights Linear transformation (min, max known )Universal transformation

18. 18 DSS-seminar, 8.12. 2008 Model behavior study Personal trust forming Number of contacts influence Number of recommendations influence Initial trust influence Reputation influence Trust disposition influence Weight of contacts effect Weight of recommendations effect Weight of reputation effect /33 Interpersonal trust model

19. 19 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

20. 20 DSS-seminar, 8.12. 2008 Personal trust – study Obr. 4: Graf utváření důvěry se zobrazením uskutečněných kontaktů a /33 Interpersonal trust model

21. 21 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

22. 22 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

23. 23 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

24. 24 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

25. 25 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

26. 26 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

27. 27 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

28. 28 DSS-seminar, 8.12. 2008 Personal trust – study /33 Interpersonal trust model

29. 29 DSS-seminar, 8.12. 2008 Information effect model Transformation – joint initial and effective probability distribution Initial probability distribution p(x) (Input) Effective probability distribution r(x) Final probability distribution q(x) (Output) Convenient measure of intensity effect evaluation: Potential solution: /33 Interpersonal trust model

30. 30 DSS-seminar, 8.12. 2008 Example: Symmetrical divergence Interpersonal trust model /33 Commodity: Apples Given % inter-weeks tolerance = 0,05% Symmetrical divergence (incr., decr.) Price CZK/kg, 2004-2007

31. 31 DSS-seminar, 8.12. 2008 Personal trust effect λ   0, 1  - effect intensity E(α,  ), 0≤α<  ≤1 - effect distribution /33 n – number of subjects, i -th subject, i -th subject Interpersonal trust model

32. 32 DSS-seminar, 8.12. 2008 Conclusion /33 Interpersonal trust model Cooperation – selection of partners (published) Cooperation – selection of partners (published) Personal trust model (submitted) Personal trust model (submitted) Phenomenal trust model (simultaneous verification) Phenomenal trust model (simultaneous verification) Trust model with intervention by agent technology application (JADE) Trust model with intervention by agent technology application (JADE) Available information: http://www.kiv.zcu.cz/~netrvalo/publikace/publikace.html

33. Thank you for your attention. Questions?