1. Social Cognitive Factors of Unfair Ratings in
Reputation Reporting Systems
A paper by Rosaria Conte, Mario Paolucci(2003)
A presentation by:
Stathis Grigoropoulos
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2. Contents
• Introduction
• Electronic Transactions: The Game Theoretic
View
• A Social Cognitive Model of Reputation
• Factors of Memetic Decisions
• Artificial Experiments Findings
• Conclusion/Discussion
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3. Introduction
• According to Oxford dictionary, Reputation is the “Common or
general estimate of a person with respect to characters or
other qualities“(What others think of us)
• Reputation is generally seen as a non-legal social mechanism
enforcing a wide variety of desired behaviors, both economic
and social
– Brings Trust to a business transaction
– Can Help You reach a given goal
– Reputation can cost/provide a job position
• Reputation has both cognitive properties and social aspects
• We will concentrate on the potential of a Social Cognitive
Model of Reputation for the optimization of electronic
transactions
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4. Electronic Transactions: The Game Theoretic
View
• Electronic media dramatically enlarge the number of people
one may interact with. At the same time, they remove the
connection between social acquaintance and physical contact.
• With the increase of the interaction range, associated risks
and Social Dilemmas increase.
• It is no surprise that electronic auctions ( Ebay ) have been
the first arena for the implementation of Online Reputation
Systems.
• Shelter users from the uncertainty of distance and anonymity
Basically:
– A transaction evaluation(TR), consisting of ratings (TR(b,s),
TR(s,b)), (b=buyer, s=seller)
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5. Electronic Transactions: The Game Theoretic
View
Online Reputation Systems:
• A Reputation System Collects, Distributes, Aggregates
information about a behavior
• Expected:
– Buyers are encouraged to sustain higher prices in order to receive the
goods
– Sellers are discouraged from cheating in order to keep reputation and
prices high
– Cooperation = f(Reputation) + Noise
• Problems:
– Misbehaving on the level of the reputation system
– Unfair Ratings
• High/low
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6. Electronic Transactions: The Game Theoretic
View
A closer look on
Reputation System:
• Buyers and sellers evaluate each other after transactions
• The evaluation is not mandatory and will never be removed
• evaluation = a comment + a rating
• comment = a line of text
• rating = numeric evaluation in {-1,0,1}
• Each eBay member has a “reputation” (feedback score) that
is the summation of the numerical evaluations
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7. Electronic Transactions: The Game Theoretic
View
A closer look on
Reputation System:
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8. Electronic Transactions: The Game Theoretic
View
A closer look on
Reputation System:
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9. Electronic Transactions: The Game Theoretic
View
A closer look on
Reputation System:
Remarks:
 Simple, yet effective
 Scores high in economic efficiency
 Seller Reputation (not buyer) has a significant effect on
the price
• Bias towards Pollyanna evaluations and underprovision
• Rate or not Rate, that is the question!
• Only 50% of transactions are rated
• Of the rated, only the 1% are negative (!)
• Low score in social efficiency
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10. Electronic Transactions: The Game Theoretic
View
A closer look on
Reputation System:
Possible Explanations:
• Game Theorists are correct
– Positive ratings because no one cheats
– Does not explain the low rate of provision and leniency
• Cheaters prosper thanks to both biases
– A seller may cheat 20% of the times and maintain a
monotonically increasing reputation value
– A “positive” equilibrium is sustained mainly by reciprocity
– Users provide positive ratings => optimism
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11. Electronic Transactions: The Game Theoretic
View
Questions Raised:
– To what extent is cheating harmful?
– Which type of cheating is harmful and to whom?
– To what extent Online Reputation Systems differ
from reputation in natural societies, and about
what?
– Are there just two parts (buyer and seller) in the
general game of reputation?
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12. A Social Cognitive Model of Reputation
• Both social evaluations concern other agents' (targets)
attitudes toward socially desirable behavior, and may be
shared by a multitude of agents.
• Image is an evaluative belief
– it tells that the target is “good” when it displays
behavior b, and that it is “bad” in the opposite case.
– Most software implementation describe image only
• Reputation is instead a shared voice, i.e. a belief about
others saying that a given target enjoys or suffers from a
shared image.
– Reputation is true when it’s actually spread, not when it
is accurate
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13. A Social Cognitive Model of Reputation
●image :
– global evaluation owned by an agent about a
target's property in relation with an agent's (or
others') goal , e.g. a social norm
●reputation :
– process and effect of the transmission of (a subset of) originally image based evaluation(s) (or
forged ones) meta-belief, i.e. a belief about
others' beliefs (either personal:”agent x says...”, or
impersonal “it is said that...”)
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14. A Social Cognitive Model of Reputation
• mental decisions based upon them can be analyzed:
– epistemic
– pragmatic-strategic
– memetic
• Reputation does not bind the speaker to commit himself
to the truth value of the evaluation conveyed but only to
the existence of rumors about it
• Only the acceptance of a meta-belief is required
• And, unlike ordinary deception, reputation implies
– no personal commitment (by no means stating that
target deserved it)
– no responsibility
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15. A Social Cognitive Model of Reputation
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16. A Social Cognitive Model of Reputation
• 4 non-empty sets of agents are defined by their
functional role:
• Image
– set E = evaluators
– set B = beneficiaries (of the social norm)
– set T = target
• Reputation
– Image sets +
– set M = memetic agents, gossipers
• Intersection between E & B is usually, non empty
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17. A Social Cognitive Model of Reputation
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18. A Social Cognitive Model of Reputation
• 4 non-empty sets of agents are defined by their
functional role:
• Image
– set E = evaluators
– set B = beneficiaries (of the social norm)
– set T = target
• Reputation
– Image sets +
– set M = memetic agents, gossipers
• Intersection between E & B is usually, non empty
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19. Factors of Memetic Decision
Memetic Decision
• The decision about whether or not to participate in a
given gossip (provision)
– If Yes: what type of gossip to spread (over or underrating)
• affects the probability that a certain gossip
propagates
• Provision is affected by(among others):
– Responsibility
– Benevolence
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20. Factors of Memetic Decision
• Responsibility
– Gossip decreases with growing responsibility (perception)
and accountability
– Increasing commitment with first hand evaluations(G=E)
• EBay transmissions are not second hand
– Commitment is a function of:
• Decreasing anonymity of the reports
• Decreasing number of gossipers
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21. Factors of Memetic Decision
• Benevolence
• The type of gossip is expected to vary according to the
direction of benevolence
– Beneficiary oriented: negativity bias
• Transmit bad even if uncertain
• Transmit good only when really certain
– Target oriented: leniency bias
• Transmit if good reputation
• Do not transmit if bad
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22. Factors of Memetic Decision
Operationalise Social Cognitive Factors
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23. Factors of Memetic Decision
Operationalise Social Cognitive Factors: Extreme Example
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24. Artificial Experiments Findings
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25. Conclusions
• Reputational systems work in different ways and are
governed by different implicit rules, according to the
structural conditions and their effects on cognitive
biases.
• Reputational systems can be valued according to at
least two different criteria, i.e. efficiency of
transactions, on one hand, and coalition and equity, on
the other.
• First-level, or material, cooperation is not necessarily a
function of good reputation
• We need to study not only the structural conditions per
se, but also the cognitive factors implied in the varying
of these conditions if we want to make predictions
about the specific effects of reputation
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26. Discussion
• To what extend can we simulate natural
reputation systems in order to optimize
(electronic) transactions?
Thank you!
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