How to use analogies

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In order to construct and use analogies effectively, one must understand what works and what does not. An analogy works best when the concept being taught is new. If the patient already has some understanding of the topic it may be better to build on the already available framework.

Use analogies only if the concept is hard to grasp. An analogy is more useful to explain congestive heart failure than a laceration.

Analogies take time to set up and explain. If the concept is simple, a straightforward explanation may be quicker and will not open the patient to possible misconceptions from misapplication of the analogy.

Make sure the patient understands the analog. If a patient has never understood a pump, the analogy will not help the patient understand the heart. Just as medical personnel assume patients know common medical terms like uterus or IV’s, we can assume too much by expecting patients will have other common points of reference. They may not understand electrical circuits, pipes, farming, pumps, or other fields that analogs are commonly drawn from. One study showed that many chemistry students learned no better with analogies. Further analysis showed that 48% of the chemistry students did not understand the analogy. It is important that the patient clearly understand the analog before trying to project that knowledge to the target. If the patient doesn't understand the analog it must be explained or abandoned.

Explain the specific similarities. Simply stating that the heart is like a pump does not focus the learners attention on how it is similar. For example: Let me explain how heart failure causes fluid in the lungs. The heart is like a pump. The heart pumps blood from one part of the body to another like a pump pumps water from a reservoir that is fed by a stream. If the pump fails to pump well the water backs up into the reservoir and eventually it overflows. When the heart doesn't pump well blood backs up into the lungs but instead of overflowing, it waterlogs the lungs, making it hard to breath. The more visual the analogy the better.

One of the greatest hazards of teaching by analogy is that the patient may transfer inappropriate knowledge from the familiar to the target and leave with misconceptions. From the above example it would be easy to picture that a common complication of congestive heart failure is rupturing the lungs like a reservoir overflows. Many other examples of misconceptions from analogies could be given since, no matter how many similarities there are between analog and target, they are still very different. Be aware of misconceptions the analogy may leave. Click here for an article about inappropriate use of analogies.

After the target concept is learned, the patient can learn new things without always going back to the analogy. The analogy helped the patient to understand the framework of the concept and the learner can now lay down more directly on this framework. Thus the learner can be "weaned" from use of the analogy.

Effective analogies

The target concept is novel to the patient.
The target concept is complex.
The analog is well known to the patient.
The analog and the target are parallel in important ways.
The ground clearly describes the similarities between the analog and the target.
Avoids causing misconceptions.

Using an analogy effectively
	Step	How?	Example	Why?
1	Is an analogy necessary?	Assess baseline understanding	"Tell me your understanding about what high blood pressure is."	Patient may already understand well.
		Is the concept difficult to grasp?	(Laceration vs. Congestive Heart Failure)	If easy subject, simple explanation may be more efficient.
2	Check for understanding of the analog	Ask patient if familiar with the situation you are comparing with.	"Are you familiar in general with how pumps work?"	If patient unfamiliar with analog, explain analog or abandon analogy.
3	Explanation of analogy	Show how similarities explain the target concept.	"The heart is like a pump. It pushes blood from one part of the body to another."	Focuses the patient on the desired principles to learn.
4	Point out limitations	Identify important ways the analogy could be confusing.	"…except the heart actually changes size as it pushes blood out."	Decreases the chance of misconceptions.
5	Check for understanding	Ask patient for questions or to make conclusions based on the analogy. Check for misconceptions.	"What questions do you have about how the heart works like a pump?" "Tell me what you understand about the heart now."	Make sure patient understands the analogy and the concepts to be taught.

Calling all analogies

If you would like to share your favorite analogies with your colleagues,

please send them my way. I will post them on our website.

Medical Analogies Website

www.altoonahosp.org/afp/analogies

You can e-mail your submissions to me at truhl@altoonafp.org. Please fully describe your analogy. If it is original or you know the source, give me your full information and I will give you credit. I suspect that good analogies are passed around like good jokes. You soon lose the source.

Help me develop this site as a resource for educators.

Terry S. Ruhl, MD

Altoona Family Physicians Residency

501 Howard Avenue

Suite F2
Altoona, PA 16601