Page 125 - Designing Sociable Robots

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and internal events of major significance for the needs and goals of a creature (Plutchik,
1991; Izard, 1977). For instance, Frijda (1994a) suggests that positive emotions are elicited
by events that satisfy some motive, enhance one’s power of survival, or demonstrate the
successful exercise of one’s capabilities. Positive emotions often signal that activity to-
ward the goal can terminate, or that resources can be freed for other exploits. In contrast,
many negative emotions result from painful sensations or threatening situations. Negative
emotions motivate actions to set things right or to prevent unpleasant things from occurring.
Several theorists argue that a few select emotions are basic or primary—they are endowed
byevolutionbecauseoftheirprovenabilitytofacilitateadaptiveresponsestothevastarrayof
demands and opportunities a creature faces in its daily life (Ekman, 1992; Izard, 1993). The
emotions of anger, disgust, fear, joy, sorrow, and surprise are often supported as being basic
from evolutionary, developmental, and cross-cultural studies (Ekman & Oster, 1982). Each
basic emotion is posited to serve a particular function (often biological or social), arising
in particular contexts, to prepare and motivate a creature to respond in adaptive ways. They
serve as important reinforcers for learning new behavior. In addition, emotions are refined
and new emotions are acquired throughout emotional development. Social experience is
believed to play an important role in this process (Ekman & Oster, 1982).
Several theorists argue that emotion has evolved as a relevance-detection and response-
preparation system. They posit an appraisal system that assesses the perceived antecedent
conditions with respect to the organism’s well-being, its plans, and its goals (Levenson,
1994; Izard, 1994; Frijda, 1994c; Lazarus, 1994). Scherer (1994) has studied this assessment
process in humans and suggests that people affectively appraise events with respect to
novelty, intrinsic pleasantness, goal/need significance, coping, and norm/self compatibility.
Hence, the level of cognition required for appraisals can vary widely.
These appraisals (along with other factors such as pain, hormone levels, drives, etc.)
evoke a particular emotion that recruits response tendencies within multiple systems. These
include physiological changes (such as modulating arousal level via the autonomic nervous
system), adjustments in subjective experience, elicitation of behavioral response (such as
approach,attack,escape,etc.),anddisplayingexpression.Theorchestrationofthesesystems
represents a generalized solution for coping with the demands of the original antecedent
conditions. Plutchik (1991) calls this stabilizing feedback process behavioral homeostasis.
Through this process, emotions establish a desired relation between the organism and the
environment—pulling toward certain stimuli and events and pushing away from others.
Much of the relational activity can be social in nature, motivating proximity seeking, social
avoidance, chasing off offenders, etc. (Frijda, 1994b).
The expressive characteristics of emotion in voice, face, gesture, and posture serve an
important function in communicating emotional state to others. Levenson (1994) argues that
this benefits people in two ways: first, by communicating feelings to others, and second, by
influencing others’ behavior. For instance, the crying of an infant has a powerful mobilizing