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A Survey of Trust in Social Networks. WANITA SHERCHAN, IBM Research-Australia SURYA NEPAL and CECILE PARIS CSIRO ICT Centre Presented by Jacob Couch. Trust Definitions. Trust Definitions. Trust Origin Trust in Psychology. - PowerPoint PPT Presentation
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A Survey of Trust in Social Networks
WANITA SHERCHAN, IBM Research-AustraliaSURYA NEPAL and CECILE PARIS
CSIRO ICT Centre
Presented by Jacob Couch
Trust Definitions
Trust Definitions
Trust OriginTrust in Psychology● Trust is considered to be a psychological state of
the individual, where the trustor risks being vulnerable to the trustee based on positive expectations of the trustee’s intentions or behavior.
● Cognitive● Emotive● Behavioral
Trust OriginTrust in Sociology● Trust is considered to be a bet about the future
contingent actions of the trustee.● Considered a level of expectation within a group.● Cognitive● Behavioral● Emotive builds over time
Trust OriginTrust in Computer ScienceUser Trust●Inherently personalized●Based on previous experience●Direct Trust–Based on interactions between users of a system.–Strength is determined based on frequency.●Recommended Trust–Experiences of Direct Trust are reflected to neighbors based on experience and sociability
Trust OriginTrust in Computer ScienceSystem Trust
●“The expectation that a device or system will faithfully behave in a particular manner to fulfill its intended purpose”–TPM
Trust Definitions
Trust Types/Facets● Calculative
● Relational
● Emotional
● Cognitive
● Institutional
● Dispositional
Trust Properties● Context Specific● Dynamic● Propagative● Non-transitive● Composable● Subjective● Asymmetric● Self-reinforcing● Event Sensitive
Calculative● “Calculation on behalf of the trusted designed
to maximize the trustor's stakes in the interaction”
● Typical economic model
Relational● Trust built up over time.● Typically used in employee relationships
Emotional● “The perceived outcome of direct interpersonal
relationships [sic]”
Cognitive● “Trust based on reason and relational
behavior”– Information channels– Norms– Sanctions
● “Positive referrals … increase cognitive trust in the trustee”
Institutional● “Trust derived from a provided environment
that encourages cooperation and penalizes misbehaviors [sic]”
Dispositional● “...over the course their lives, people develop
generalized expectations about the trustworthiness of other people”
Properties of Trust● Context Specific● Dynamic● Propagative● Non-transitive● Composable● Subjective● Asymmetric● Self-reinforcing● Event Sensitive
Context Specific● “Trust is context specific in its scope”● Would you trust your mechanic to be your
dentist?
Dynamic● “Trust can increase or decrease with new
experiences”● As a relationship decays, the amount of trust
typically decreases
Propagative● “Alice trusts Bob who in turn trusts John”
– Alice can derive some amount of trust on John● Trust can be based on the friend of a friend
mode, but it is not transitive
Non-transitive● “Alice trusts Bob who in turn trusts John”
– This does not imply that Alice trusts Bob
Composable● Alice trusts Bob and Charlie. Charlie trusts
John. Bob trusts John– Trust through propagation can be composed to
create a greater trust.
Subjective● Social trust is subjective to the rater.● If Alice thinks that Bob's opinions are good,
John may not think that Bob's opinions are good.
Asymmetric● Trust is asymmetric between members of a
relationship.– The amount that Alice trusts Bob is not the same
amount Bob trust Alice
Self-reinforcing● “Members act positively with other members
whom they trust.● “if the trust between two members is low... it is
unlikely that they will interact”
Event Sensitive● “Trust take a long time to build, but a single
high-impact event may destroy it completely”
Trust Models● Statical/machine learning
– Artificial Neural Networks– Hidden Markov Models
● Heuristics● Behavior based
Social Networks
Social Network Examples
Properties - Homophilly● Social pattern to associate with similar others● Social properties include race, ethnicity, age,
religion, eduction, occupation...
Properties - Small-world phenomenon● The concept of the “Kevin Bacon” effect.
– All persons are connected within 6 degrees
FOAF - Friend of a Friend● Most modern social networks use friend of a
friend as a boundary of private information. ● The underlying, but not necessarily correct,
assumption is that friendships are transitive.
Social Capital● No universal agreeable definition● “. . . a collective resource that facilitates
cooperation at the small group level. . . . no longer resides with an individual but exists through relationships between actors . . . is based on the density of interactions . . . ”
Social Trust● Aspect of social capital that represents
cooperative infrastructure.● “By analogy with notions of physical capital and
human capital—tools and training that enhance individual productivity— ‘social capital’ refers to features of social organization such as networks, norms, and social trust that facilitate coordination and cooperation for mutual benefit.”
Process of Social Trust
Trust Information Collection● Attitudes● Behaviors● Experiences
Attitudes● “And individuals degree of like or dislike”● Affect
– Emotional response that indicates personal preference● Behavior
– Tendency of an individual● Cognition
– Beliefs about an object
Experiences● Perception of members through interactions● Must be measured through feedback
Behaviors● Patterns of interactions● Trust is the community is measured by the
frequency of interaction
Evaluation of Social Trust● Network Structure/Graph-Based Trust Models● Interaction-Based Trust Models● Hybrid Trust Models
Network Structure/GraphRequires feedback from user on interactions● Golbek proposes FOAF rating on a scale of 1-9● Ziegler/Hang propose method to calculate trust
between two groups of people on aggregate of ratings● Caverlee proposes feedback rating mechanism after
each social interaction● Maheswaran proposes social trust based on ratings
plus social network connectivity
InteractionBases model purely on interactions of members● Nepal proposes model on popularity trust and
engagement trust● Adali proposes model based on conversation
trust and propagation trust
HybridCombines Network structure and Interactions
Trust Dissemination● Trust Based Recommendation Models
– Provide per object recommendations to user● Visualization
– Provide visualization to user to show trustworthiness of members for general consumption
Trust Definitions
Analysis
Analysis
Analysis Computer Science trust is normally
numerical and comparing against a threshold, Sociological and psychological responses should also be evaluated.
Properties such as asymmetry, self-reinforcement, and event sensitivity are typically not evaluated in the trust equation.
Areas for Future Research Evaluation of Tie-Strength Visualization of Trust
◦ Can be used to help service providers identify healthy and unhealthy networks
Resistance to malicious attacks in P2P systems
Conclusion● Trust models in modern online social networks
are still very primitive● Human social network properties can be
ported to online social, thus allowing the use of existing sociological research
● Social capital can be used to cultivate trust of an online social network
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