The ranges we propose for each variable are arbitrary, and are intended for use in functions that simply treat the variables as multiplicative factors. However, an attempt has been made to partially order the effects the variables have on intensity calculations by differentially limiting the values over which each variable may range. No claim is made for psychological fidelity on this account. This is not as critical as it might seem, since each of the values within the ranges must, in all cases, be given as an assessment, either direct or indirect, of some feature value. Once a scale has been established it is used as a reference for interpreting events and internal states of the agent. If a range proves, in practice, to be too high, it tends to be used more conservatively than if it is too low, and vice versa.
Moreover, the ranges we have specified for variables are not important to the design of our intensity architecture. Instead we have merely provided arbitrary first designations for these ranges, based loosely on introspective analysis. These ranges, default values for variables, and the intensity functions that use them, have been isolated in the implementation, and are treated essentially as data, so that they may be easily altered to reflect the current cognitive theory.
In the basic intensity functions given at the end of this article we use values for the intensity variables as factors: those values below 1 reduce the strength of the emotion, those above 1 increase it. In the current model, primary determinants of emotion intensity range from zero to 10, with a default of 3. Factors which are treated as weaker modifiers of intensity range from (approximately) zero to 3. Modifiers which, within our model, can only reduce intensity, range from zero to 1. Variables whose effects on intensity calculations are determined by the valence of an emotion (such as a variable which heightens the intensity of negatively valenced emotions but lessens the intensity of positively valenced emotions) are given both a bias value, and a strength ranging from 1 to 3.
It is not desirable to have to specify a value for each of the
intensity variables in each emotion eliciting situation that arises in the
simulation. In addition, some variables (such as that representing the
concept of surprise), which we might desire to represent in a particular
situation, are sometimes difficult, if not impossible, to
calculate.
Intensity functions that are designed to use the missing values, must
therefore either use an alternate calculation method, or must use defaults,
as is done in the current implementation. Because in this implementation
intensities are calculated by multiplying the intensities of component
factors together, we use a default value of 1 for most variables since this
then gives them the convenient property of affecting the intensity
calculation only when otherwise specified.