perception and organized action systems at birth to the sense of self and
others as differentiated and reciprocal agents by 2 months that leads to the
sense of self and others as differentiated and reciprocal agents who can
reciprocate as well as cooperate by the end of the first year. At this point in
development, infants are starting to take an intentional stance in addition to
the contemplative stance they develop by 2 months of age. In a final
discussion, we speculate on the possible mechanisms underlying this devel-
opment. But first, we set the stage by presenting some general considerations
regarding the specificity of social knowledge in comparison to physical
knowledge and the specific processes underlying social cognition, namely
intersubjective mechanisms.

The understanding of people determines special knowledge and entails
much more than physical knowledge. Although people have bodies, and
physical knowledge can account for part of their behavior (e.g., the fact
that they can move on their own, can hide or fall, are subject to the forces
of gravity, and cannot be at two different locations at the same time),
monitoring people and predicting what they are going to do next entails
skills that go far beyond physical understanding. Understanding people
also defines special processes. Social cognition entails the reading of affects,
emotions, intentions, and subtle reciprocities: all the things that make
people fundamentally different from objects. In other words, it entails the
understanding of a private or dispositional world, what people feel and what
characterizes their individual inclinations. But how do we get access to
such understanding?

To a large extent, people reveal themselves in the way they reciprocate
to us and how, via reciprocity, they convey a sense of shared experience.
The same is true for animals and pets. Understanding an animal of a
particular species observed in the wild or at a zoo, even for extended
periods of time, is different from the understanding of the same animal
raised as a pet and with whom we share our life. A sense of shared expe-
rience adds to social understanding and gives deeper access to the dispo-
sitional characteristics of individuals, whether they are humans or nonhu-
mans. The sense of shared experience that emerges from reciprocity is
captured by the term intersubjectivity. We will use this term extensively in
this chapter, because we believe that the emerging sense of shared expe-
rience determines the early development of social cognition.

Intersubjectivity entails a basic differentiation between the self and oth-
ers as well as a capacity to compare and project one's own private experi-
ence onto another (e.g., the "like me" stance). Pet owners obviously un-

-5-