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distinguish self-propelled from other-propelled objects (Premack, 1990). Studies with infants
also indicate concepts of hurting, helping, reciprocity, belonging to a group, ownership, and
liberty and also that infants have certain expectations concerning the interrelations of these
concepts (Premack and Premack, 1994). Even though infants do not speak, their preferential
looking (noting which image the infant prefers to look at) and habituation (presenting the infant
with a stimulus repeatedly until it starts to respond for shorter periods of time) can be measured
as responses to images of dots and lines on a computer screen. Preferential looking shows
interest or surprise, so it reflects how the infant expects physical objects to behave. Habituation
can be used to measure how well the infant makes discriminations.
Turning briefly to adults before returning to children: Adults will automatically see
certain kinds of dot-and-line behavior as goal-directed. For example, if there is a broken vertical
line on the screen and a dot right next to it moving up and down just to the point of the break in
the line, the adult will see the dot as trying to pass through the break. Generally speaking,
persistent action toward a single item is seen as goal-directed. Liberty, entrapment, and
aesthetics are also readily perceived. A bouncing dot can become trapped in a virtual hole. A dot
bouncing higher and faster is seen as more attractive than one bouncing lower and more slowly.
These concepts can be used to gauge perceptions of helping and hurting. If one dot restores the
motion of another dot trapped in a virtual hole, in other words if one dot frees another, this will
be seen as helping. If one dot causes another to be more attractive by causing it to bounce higher
and faster, this too will be seen as helping. Not surprisingly, causing a dot to lose its liberty or be
less attractive will be seen as hurting. Furthermore, soft and weak motions among dots will more
likely be coded as positive and hence will more likely be seen as helpful. By contrast, abrupt and
strong motions will more likely be coded as negative and hence seen as hurting (Premack and
Premack, 1994).