tive, it can be used prescriptively to determine the characteristic of viral marketing strategies
appropriate in different contexts.
Background
Social information-processing theory provides a useful lens to examine the interpersonal
influence processes that are the hallmark of viral marketing since it views the social network
as an important source of information and cues for behavior and action for individuals
[11]. Prior studies examining the diffusion of innovations and the transmission
of ideas in social networks have viewed the interpersonal influence as occurring largely
from face-to-face interactions [3]. However, interpersonal influence in viral marketing
occurs in computer-mediated settings and is significantly different from that occurring
in conventional contexts in several ways.
First, the scale and scope of influence is considerably expanded—computer mediation
allows a much larger number of individuals to be connected by informational
linkages than feasible through face-to-face contact or through conventional media
such as the telephone. For instance, the effort to email a message to all contacts in the
address book is only marginally more than the effort in sending the message to just
one recipient. On average, the reach of individuals—the number of connected others1
that they can influence, increases considerably. Further, this reduction in the effort
needed to reach out to others increases the number of occasions when individuals act
on their natural impulse to share knowledge and pass along information they consider
useful and timely to others in their social network. Together, this results in an enormous
increase in the extent of influence through knowledge-sharing and information
transfer in online networks.
Second, computer-mediated communication media provide the unprecedented
ability to connect individuals synchronously (for example, using instant messaging)
as well as asynchronously (through email). The new media thus broaden the availability
of recipients, literally enabling influencers to access connected others aroundthe-
clock. Third, in many cases, the media provide realtime feedback on the impact
of influence, enabling motivated individuals to rapidly adapt their influence strategies
and progressively enhance the effectiveness of their influence attempts. As a result, the
ability to exert influence is considerably enhanced [11].
Overall, the ability to influence a large number of individuals, the minimal effort
required to make influence attempts, and the flexibility to deploy a variety of influence
strategies through information technologies are a potent combination making
influence in online social networks considerably more compelling and pervasive than
in conventional interpersonal interactions.
Framework for Viral Marketing
We highlight two factors that play a key role in determining the nature of influence
episodes in viral marketing. The first is the role of the influencer—whether the attempt to
influence is passive or actively persuasive. The second is the level of network externalities—
the additional benefits accruing from broader usage of the product or service being recommended
within a user community. Network externalities in the case of a product or
service are benefits, in addition to those directly derived from usage, that accrue broadly to