Sensations

All emotions in embodied creatures are initiated by sensations.

A sensation is an immediate reaction to a creature's current status.

By definition, sensations are experienced practically instantaneously, based on changes in the current situation. Two factors may cause sensations: the current perceptions (that is, stimuli from the environment), or cognitive activity (that is, thinking). Table 37.1 lists common sensations.

Table 37.1. Common Sensations That Can Be Observed in Living Creatures

Surprise	Anticipation
Disgust	Attraction
Confusion	Discovery
Pain	Pleasure

Perceptual Sensations

Typically, a sensation is triggered by perceptions. The body detects stimuli from the environment, and the information causes an immediate reaction in the brain. For example, a nonplayer character (NPC) may experience a sensation of surprise when a player appears suddenly.

Embodied creatures are defined by their interaction with the world, so the perceptual type of sensations will be the most common (see Table 37.2). The reactive techniques studied throughout this book are appropriate for creating such reactive emotions.

Table 37.2. External Stimuli from the Environment That Cause Sensations

Health and armor lost	Blood splat
Sparks/explosion	Object disappears
Arriving lift	Door opening
Enemy presence	Desirable object

Cognitive Sensations

Sensations may also be triggered by reactions to the mental state (for instance, knowledge of the world or other emotions). Here, basic processing of information in the brain causes the sensation. For instance, surprise can be caused by an object not being present, when the animat thought it should be there.

Sensations based on cognition and perception have common traits: Both are triggered when a pattern is matched in the brain. With perceptions, this pattern is matched instantly based on sensory information. On the other hand, some cognition is necessary before a pattern develops in the brain (by thinking), which eventually engenders a sensation instantly when a pattern is matched.