Ventana software support forum

Several recent postings address the question of whether and how to include human
motivation in SD modeling.

Has anyone looked at Fuzzy Logic (a la Lotfi Zadeh) as a mathematical basis for
creating the necessary algorithms? Zadeh invented it in the first place as a
means of representing the way the mind deals with imprecise data and imprecise
definitions, in the process of coming to every-day decisions.

Bill Cutler
72734.3452@CompuServe.COM

Bill Cutler asked about modeling human motivation, and about fuzzy logic.

Human motivation:
Psychological SD models with which I am familiar have addressed topics including
Hysteria (Wegman 1977), Response to Authority (Richmond 1977), Mid-Life Crisis
(Dabiri 1979), Alcoholism (Goluke 1981), Worker Burnout (Homer 1985), and Eating
Disorders (Homer 1986). In 1988, Ralph Levine (psychologist at Michigan State)
and I prepared a set of generic causal loops dealing with the psychology of
performance. Several of the specific topics could be explained pretty nicely as
special cases of the general framework, as well as other topics including
boredom and depression. The framework is also nifty in that it can explain a
broad continuum of performance, from normal to mildly dysfunctional to severely
dysfunctional. The framework integrates key concepts from all of the major
psychological theories bearing on human performance, including Learning Theory,
Expectancy/Motivation Theory, Information Processing Theory, Psychosomatic
Theory, and Appraisal and Coping Theory. The framework has not been published,
but is in a reasonably complete form Id be happy to send out to anyone
interested.

Fuzzy logic:
See the article "Fuzzy system dynamics", by Tessem and Davidsen, System Dynamics
Review, Vol 10 No 1, Spring 1994. They operationalize fuzzy numbers as
parameter ranges (with a trapezoidal density function) for sensitivity testing.
The testing can be deterministic or stochastic (Monte Carlo-style), with
possible correlation among fuzzy variables. Thus, fuzzy logic for SD purposes
may be viewed pretty simply as sensitivity testing with a particular type of
density function.

Jack Homer
70312.2217@CompuServe.COM