Benefits: The use of related stimuli is the gold standard for inducing artificial emotions across practically every media known to man. Great novels, paintings, movies, and poems rely on their intense portrayals a human experience that is not our own, but close enough to tap into our personal experiences. As a creator, this is technique is quite cost effective and most of us have been trained in its application.
Limitations: Relevant stimuli is amazingly powerful, but has some limitations when it comes to use in games.
"She begins to dance. At first her movement is controlled and intricate. The screen pulsates and she yells to its beat."
Not all techniques at our disposal create both a physiological response and cognitive labels. There are some that just do one or another. Such techniques can be used as building blocks in a larger system.
One well-studied technique that affects that body is bio feedback. This is particularly interesting to game developers since it is a fundamentally interactive technique and offers deep opportunities for mastery-focused gameplay.Theory: In the classical model of human behavior, there is the somatic nervous system which controls voluntary actions like moving your arm and the autonomic nervous system which attempts to maintain homeostasis by automatically adjusting such things as body temperature or heart rate.
A surprising number of automatically controlled systems can in fact be influenced consciously. The most obvious one is breathing, as seen by pearl divers holding their breath. Other systems can be controlled indirectly by consciously adjusting related systems. For example by staying stationary, slowing your breathing and thinking calming thoughts, you can slow heart rate.
If only we could encourage the player to directly control their physiological state, they could
consciously put themselves in a state that was conducive to feeling
the desired artificial emotions. Unfortunately, people are generally
quite poor at recognizing and attaining mastery over systems such as
the autonomic nervous system that have poorly-visible second order effects
that are only loosely connected to the original action. Most people
couldn’t tell you their heart rate and even fewer could tell you how
they could consciously speed it up or slow it down.
We see this problem of controlling second order effects pop up in games all the time. Suppose you add a switch that unleashes an AI monster, that then steps on a switch that opens a door off screen. The end result is that users complain that they have no idea why things are happening. The chain of events between cause and effect is too long and confusing for the user to form a testable mental model of the system.
In order to teach the user how to control second order interactions, the game designer has to provide lots of clear, concise feedback and plentiful rewards for the right actions. Biofeedback applies these game design principles to the task of influencing the autonomic nervous system.