game-theoretic analysis of the psychology of online reputation systems
online reputation systems, exemplified by ebay's seller and buyer
feedback system, employ a signalling reputation paradigm.
In these systems, the emphasis is on promoting trust, not on sanctioning
bad behavior. Although users have the option of leaving negative
feedback, empirical research (Resnick & Zeckhauser, 2002) suggests
that negative feedback is often grossly underreported in these systems,
which is the desired result for the ecommerce merchants hosting
these reputation systems. It seems that the cause of this phenomenon
is rooted in the publicity of the reputation feedback.
Contrast signalling reputation systems with gossip-based reputation
systems which lacks this publicity criteria. Because gossip
about a person is decentralized over that person's social network,
and the gossip data is often held in confidence and difficult to
trace, negative reputation is allowed to flourish in the shadows.
Machiavellianism would suggest that, given the opportunity to gossip
without accountability, people would need very little incentive
to spread negative gossip. Gossip-based reputation systems thus
follow a sanctioning reputation paradigm, where negative
feedback is sure to catch up with and can possibly be used to ostracize
publicity of reputation feedback in the ebay-style reputation system
promotes positive feedback and resists negative feedback. 1) Users
view giving positive feedback as social capital. Buyers giving positive
feedback to sellers usually receive reciprocally positive feedback
for themselves. Thus improving someone else's reputation will enhance
one's own reputation. 2) Users also see positive feedback as a type
of online social courtesy for a transaction, like saying, "Thank
you" to the store clerk that bags your groceries. 3) Negative
feedback is discouraged because the information is not anonymous
and quite public. 4) Giving negative feedback could result in reciprocal
negative feedback, a loss of opportunity to do future business with
someone, and other forms of retribution. 5) Giving negative feedback
is generally rude. 6) Sellers do not want to sell to buyers who
are quick to give negative feedback.
a game theoretic view, we can say that the ebay-style reputation
system promotes cooperation. Even if a buyer or seller's experience
is negative, it is to everyone's advantage to leave positive feedback
and suppress negative feedback. Suppose a buyer purchases something
and receives in late and damaged. The damage is done already. If
he chooses to leave negative feedback, he risks receiving negative
feedback at the most and will certainly lose the opportunity to
gain positive feedback at the least. Thus, negative feedback leads
to the same, or a lower reputation. There is no reward to the
buyer for leaving negative feedback. If a buyer leaves positive
feedback, she is likely assured of positive feedback. Thus, positive
feedback leads to the same, but most likely, a greater reputation.
There is no punishment for misrepresenting a negative experience
with positive feedback. It is easy to see that the publicity
of the ebay reputation system is the critical condition for making
this system a signalling reputation system.
contrast, gossip-based reputation systems are largely private, and
thus, do not possess the accountability qualities of a system like
ebay's. In a gossip-based reputation system, a person's reputation
is not held publicly and centrally, but rather, is diffused throughout
the person's social network. At every node in the diffusion of reputation
information, the reputation information is likely to be corrupted
or manipulated for competitive or political gain by the manipulator.
"Gossip" is hard, but not impossible to trace. The psychology
of gossip is also different from the psychology of leaving feedback
in a central and public way. Saying something bad to someone's face
is always harder than saying it behind their back because we do
not feel as much accountability nor do we perceive any immediate
threat of sanctions. In Information Warfare, Hess and Hagen
suggest that gossip can be even more damaging when people mobilize
into groups to collectively assault a person's reputation.
can also take the game theoretic view of gossip-based reputation
systems. Inherent in acommunity or social network are competitive
pressures for resources or prestige. By gossiping positive reputation
information about a person within the network, there is no expectation
that if and when that positive reputation actually reaches that
person, there will be any attribution to the originator of that
feedback. Additionally, enhancing the reputation of another (unless
both parties are within a coalition) will only cause one's own reputation
to be relatively reduced. Thus, positive gossiping will not
generate reciprocation because attribution is lost and will likely
lower one's own reputation relatively speaking. By negative
gossip, there is little risk that the originator or manipulator
of the gossip will ever be known to the target of the attack. If
the attack is successful, the originator or manipulator of the gossip
can gain reputation relatively. Thus, negative gossip bears
little risk to the gossiper and can lead to increased reputation
for the gossiper (relatively speaking).
comparing public reputation systems and gossip reputation systems
used a game theoretic framework, we can see that the accountability
of public reputation systems skews reputations to be more positive
in general, whereas the lack of accountability and the competitive
nature of social network gossip skews reputations to be more negative
in general. Sanctioning in gossip reputation systems is somewhat
explicit, whereas a "sanction" in a public reputation
system is implicit and usually expressed as a user who is out-reputed
by his competitors, failing to garner as much attention as them.
public and gossip reputation systems for eBay
public and gossip reputation systems have a place and role in ecommerce,
and they are compatible with each other. Ebay's system, while promoting
trust in the use of their markets, fails to reveal negative reputation
information to potential consumers. The solution may be to embed
a gossip reputation system within the existing public reputation
system, which is still useful because it promotes trust in the community.
Consider the following design.
X wants to buy something from User Y. User X can read the public
reputation infomation on User Y, but suspects there is more negative
experience not being reported. User X broadcasts a request for information
to all the other users who have dealt with User Y and have privately
recorded negative feedback they chose not to publish. User Z's personal
agent responds because User Z has had previous dealings with User
X and trusts User X to not tattle-tale. On the basis of this trust,
User Z's agent releases private feedback to User X, either signed,
or anonymously. Included is User Z's own reputation. In this way,
users can provide negative feedback to warn other potential buyers
without fear of retribution. In fact, these users can still publicly
come out as being positive on someone and enjoy the usual benefits
of the public reputation system. User Z has motivation to release
private reputation information to User X because there is a reciprocal
agreement between the two users to share private information.
positive testimonial/negative gossip scheme for reputation in online
dating can be a perilous forum. Participants search for potential
matches and only have a potential mate's own self-description to
go on. Often these self-descriptions are deceptive, and there are
only so many assessment signals that can be read from such a profile.
This is a forum where collaborative sharing of dating experiences
with other members could be personally beneficial. However, the
twist is that this forum is competitive by its nature. Bill will
not want to share information with John on Mary because Bill and
John are competitors. If Bill feels positive about Mary, he will
want to conceal that from John. If Bill feels negative about Mary,
he may actually want to pigeonhole John into a match with Mary to
free up competition over other women. A central public reputation
system will not suffice to provide warnings about negative reputation.
If Mary has racked up negative feedback, she will simply leave the
community or choose a new login name.
as with ebay, it seems that the best reputation system may be to
maintain positive and negative information through separate systems.
A positive testimonial system can be used to help males and females
who have had positive dealings to cross-promote. They can enhance
each other's positive reputations and these scores can be used to
increase the prominence of a user in the results pages of potential
suitors. However, a potential suitor cannot just go on positive
reputation, since this only measures certain dimensions of reputation,
such as social eptness. Also, it should be expected that such positive
feedback will not be extremely informative. A male will want to
leave positive testimonial for a female in hopes of reciprocation,
but, unless he is completely uninterested in that person, he will
probably leave fair vague praise.
information must be handled differently, and a gossip system is
preferable because there is no means of retribution. Negative gossip
is treated as a commodity. It reveals dimensions of reputation not
covered by positive reputation. In the following diagram, I illustrate
the trade and barter of negative information.
man labeled "81" is seeking gossip about the female. He
receives only a fraction of the negative gossip on the female, proportionate
to his "participation score" of 81. He has gained this
score by previously recording feedback about his experiences with
other women. Each time someone has accessed his feedback and judged
it to be helpful and informative, his participation score has been
rewarded. This is similiar to a measure of his reputation and expertise.
Comparable systems exist in Amazon's book review system and Epinions.com's
expert reviewers. Others are encouraged to accurately report the
helpfulness of comments because if a person judges man "81"
as not helpful, future gossip will be suppressed from this person.
Men are encouraged to help out others because without being helpful,
he himself will not receive help. Of course, a dyadic information
bartering system would seem more fair, however, there may not be
enough information reciprocity to motivate bartering between most
men, e.g. it is unlikely that male X has info on female A and wants
info on female B, and male Y has info on female B and wants info
on female A. Thus, I opted for a community measure of participation.
positive reputation system is motivated by cross-promotion and enables
signaling, while the gossip reputation system is motivated by inside
information as a commodity, and enables sanctioning/warning. By
treating positive and negative reputation information separately
in subsystems that best suit each, we can leverage their combined