Sometimes, the mental models we construct are basically wrong, even when some of the information that was used in constructing the model is objectively correct. It is difficult to recognize when our mental models are leading us astray, especially when we can attribute poor decisions to other factors.
Consider this health model believed by many physicians in the early 1900s:
Model:
A seriously ill individual would recover from their illness if the sickness could be drawn from their bodies.
Belief:
Leeches could rid the body of illness.
Evidence:
Sometimes when leeches were applied to a sick person, she would recover.
Wrong information? When the leeches did not lead to improved health, then the physicians concluded that the patient was too sick for even the leeches to help. When the patient recovered, the physicians took this as evidence that their model of illness was accurate. In this way, they maintained their belief that leeches were important in sucking the sickness out of their patients. Without being aware of it, the physicians built, used, and maintained a health model that led to errors in health-related decisions.
