Chapter 3: Thermostats, Lemons, and Other Families of Models Summary and Analysis

The heating/cooling system that includes a thermostat has a process that mirrors the model of many behavior systems. It is illustrative of a cyclical process that generates alternating ups and downs. The process contains mechanisms that cause a rising variable to under perform and then over perform. It is designed to "seek" the appropriate level. Applying this model to human behavior, a scientist who managed a measle-vaccine program in a poor country found that once the vaccine had suppressed the disease that mothers would stop having infants vaccinated. The disease would then reappear and would once again be defeated by the inoculations only to rise again when mothers determined the disease was wiped out.

The thermostat model reminds one to expect a lag time in other...