Who Needs Emotions? The Brain Meets the Robot

how do we decipher others’ minds? 151
Interestingly, a similar involvement of autonomic mechanisms has been
observed in the context of emotions. Lang (1979) proposed that emotional
imagery can be analyzed objectively as a product of information processed
by the brain and that this processing can be defined by measurable outputs.
Indeed, experimental findings similar to those described for motor imagery
have been reported with emotional imagery. Levenson, Ekman, & Friesen
(1990), for example, showed that imagining or mimicking an emotional state
induces in the subject the appearance of physiological reactions specific for
the imagined or mimicked emotion (Chapter 2 [Adolph] for a review).
SIMULATING OTHERS’ MINDS
Mental imagery is only one of the forms an action or an emotion representation
can take. In this section, another form of representation is described,
which relates to social interaction between people. Following the simulation
hypothesis laid down in the first section, we will develop the idea that
the mechanism for understanding the actions and emotions of other selves
can be conceived as an extension of the mechanism of oneself having intentions
and feeling emotions. We will first describe the conditions for bodily
movements and expressions to be recognized as actions and emotions,
respectively. Then, we will discuss the advantages and limitations of the simulation
theory in explaining how we understand others.
Conditions for Action and Emotion Recognition
What makes an action performed by a living being (a biological action) so
attractive for a human observer? What are the conditions that have to be
fulfilled for a visual stimulus to be treated as a biologically significant action
or emotional expression? Consider, for example, the classical experiments
of Johansson in the early 1970s. He equipped a human actor with small lights
placed at the level of his trunk and limb joints. The actor was moving in
complete darkness, except for the small lights. The actor’s movements (e.g.,
walking or dancing) are immediately recognizable by an observer, even
though the actor’s body cannot be seen. Visual information reduced to the
trajectories and kinematics of the actor’s movements is sufficient to provide
cues not only to the activity portrayed by the actor but also to his age and
sex (Johansson, 1973). A display of the same, but stationary, lights will not
provide any recognizable information. Very young infants also easily distinguish
biological movements from motions produced by mechanical devices,
(Dasser, Ulbaek, & Premack, 1989).