For the fourth year, we are collaborating with the ALiEM Faculty Incubator Program to serialize another volume of Educational Theory made Practical. The Faculty Incubator program a year-long professional development program for educators, which enrolls members into a small, 30-person, mentored digital community of practice (you can learn more here); and, as part of the program, teams of 2-3 participants author a primer on a key education theory, practically linking the abstract to practical scenarios.  

They have published their first and second e-book compendium of this blog series and you can find the Volume 3 posts here (the e-book is in progress!) As with the previous iterations, final versions of each primer will be complied into a free eBook to be shared with the health professions education community. 

Your Mission if you Choose to Accept it:

The ALiEM Faculty Incubator Program would like to invite you to peer review each post. Using your comments, they will refine each primer. No suggestion is too big or small – they want to know what was missed or misrepresented. Whether you notice a spelling or grammatical mistake, or want to suggest a preferred case scenario that better demonstrates the theory, they welcome all feedback! (Note: The blog posts themselves will remain unchanged.)

This is the seventh post of Volume 4!  You can find the previous posts here: Cognitive Load Theory; Epstein’s Mindful Practitioner; Joplin’s Five-stage Model of Experiential Learning; Maslow’s Hierarchy of Needs; Miller’s Pyramid and Multiple Resource Theory.

Prototype Theory

Authors: Meenal Sharkey (@MDSharkAttack); Mary Bing; Kimberly Schertzer (@KASchertzer)

Main Authors or Originators: Eleanor Rosch

Part 1: The Hook

A new intern is managing a patient with hypotension and tachycardia. The patient is ill-appearing but alert and conversant. The intern recognizes that this is a sick patient in shock. Her attending asks her what type of shock she thinks this is, as each type of shock is managed somewhat differently. The intern is feeling overwhelmed, and the only type of shock she can think of is septic shock. She understands that the definition of shock includes inadequate end-organ perfusion, but has difficulty coming up with other types of shock (such as hypovolemic, cardiogenic, neurogenic shock). The attending is wondering how best to utilize this situation as a teaching opportunity for the intern to learn other types of shock.

Part 2: The Meat

Overview

From the field of Cognitive Science, Prototype Theory is based on conceptual organization for categorizing various items based on common features. These features are not necessarily defining features, but more of a resemblance that can be related to all the items within the family. In contrast, classical theory requires that all items meet a distinct criteria for membership in a particular group. That is, it either belongs or it doesn’t. The boundaries for membership are distinct. To be in the category, it has to be clearly defined and mutually exclusive. In Prototype theory, the boundaries can be “fuzzy.”¹

In Prototype theory, within the organization, some items resemble a “prototype” more than others. There is not usually a defining feature that is required for an object or idea to be included in the grouping, but certain objects and ideas “embody” the classification more so than others. That is, the most central member serves as the best example of that category. For instance, under the classification of “clothing,” the item of a shirt more often embodies this concept than say, a cumberband, however a cumberband would still be included within this grouping². Within the realm of educational theory, prototype theory also can represent organization of ideas that have shared characteristics.³

In medicine, patients present with a chief complaint or constellation of symptoms and not a diagnosis. For example, a patient might complain of bloody cough. We know the differential diagnosis for bloody cough is broad and can include pneumonia, malignancy, pulmonary embolism or tuberculosis, to name a few. Let’s presume we use Classical theory and assign “bloody cough” to the pulmonary embolism category. Then you could only have a pulmonary embolism if you also had a bloody cough. We know this would cause us to miss potentially serious causes of disease and potentially misdiagnose or mismanage the patient. Since, in reality, one symptom can fit into multiple categories, prototype theory lends itself better than classical theory to develop a conception of disease categories in order to facilitate the learning and problem-solving process in clinical decision-making within medicine⁴.

It is important to note the distinction between an Exemplar and a Prototype approach to categorization. They are similar in that members resembling the prototype or the exemplar are more “typical” members of the category but a prototype is not an actual existent member of the category while an exemplar is. Within prototype theory, when a new stimulus or member is encountered, typicality is compared in resemblance to the prototype as a gradation. The more the member resembles the prototype, the easier and faster it is recognized and subsequently retrieved. Within exemplar theory, a new stimulus is compared to all the prior members encountered in the past⁵. Within one’s memory, exemplars are stored in episodic memory, which entails personal knowledge based on prior experience, and prototypes are stored in semantic memory, which stores general knowledge not drawn from personal experience⁶.

Using Prototype theory, educators can teach the “textbook presentation” of the disease even if the learner has not encountered a real patient with the diagnosis, drawing upon previously solidified diagnosis and pathophysiology. Throughout the course of a learner’s medical training, educators can point out the atypical presentations of diseases by contrasting them with previously formed “typical” presentations.

Background

Prototype theory was first proposed by Eleanor Rosch in 1973 after studying how the Dani people in New Guinea classify colors. Their language does not include specific names for colors and instead categorizes them on a spectrum of dark/light or cool/warm. However, they were still able to communicate their ideas of color despite the lack of exact names for colors. This inspired her to investigate how different cultures categorize different ideas^{7, 8.}. Thus, the prototype theory was formed. This was in contrast to the classical theory of categorization, which involved defining features to rule in or rule out resemblance. The prototype theory has more of a clustering approach with the central idea/theory serving as a prototype; radially affiliated concepts can closely or loosely resemble the prototype. This concept addressed an inherent problem within classical theory: often times, definitions were not always agreed upon. Within the prototype model, even loose associations are tolerated, allowing a broader range of concepts to be included. One large benefit of the prototype theory is that retention often increases as there is a graded concept of relatability².

Modern takes or advances

An interesting aspect of prototype theory is that it can be applied to many different fields including psychology, linguistics, mathematics, medicine, philosophy, and even quantum physics. One of the most recent advances in this theory involved application within the field of quantum physics; they used mathematical quantification of classification to define “data on conceptual combinations.” This application attempted to quantify the “relatedness” of various concepts that were radially related based on the prototype theory².

In medicine, Bordage et al⁴ performed experiments which demonstrated that learning medical concepts is easier when key disorders are studied within a category and then extrapolated out, rather than learning every single diagnosis within a disease category. Papa et al⁶ found that use of Prototype theory can improve medical student diagnostic abilities and can be used to develop student clinical skills with a carefully designed curriculum. The prototype framework or prototype theory assumes that multiple encounters with related diseases lead physicians to remember the common denominators, resulting in single prototypes in long-term memory.

Other examples of where this theory might apply in both the classroom & clinical setting

• Relating various treatment plans to the “most common” presentation.
  • A patient with atrial fibrillation with rapid ventricular response in a stable patient with unknown onset can be managed with treatment of the underlying cause, calcium channel blockers, beta-blockers, or possibly digoxin. Using this as the “prototype,” extrapolating from this, a patient with atrial fibrillation with rapid ventricular response in a stable patient with known onset can be managed with synchronized cardioversion. Conversely, a patient with atrial fibrillation with rapid ventricular response in an unstable patient can also be managed with synchronized cardioversion but with additional risk for stroke and possible medical management afterwards.
    • Is a great learning tool for interns and second years to build off what they know based on their current curriculum and expand upon it.
• Organizing potentially complicated ideas.
• In the clinical setting, the prototype theory (with semantic knowledge) can aid in the speed of retrieval of the information for illness scripts.
• How we categorize various illnesses upon initial evaluation may have implications in how we recognize similar and dissimilar patient presentations and to see fit within the disease category.
• Illness Scripts in Problem-based learning often relies on Prototypes of disease processes.

Annotated Bibliography of Key Papers

Aerts D, Broekaert J, Gabora L, Sozzo S. Generalizing Prototype Theory: A Formal Quantum Framework. Frontiers in psychology. 2016;7:418.²

This paper attempts to mathematically quantify the relationships between words and concepts. One of the challenges is the “creative flexibility” that is inherent to the prototype theory. This paper was interested in the “conceptual distance” between the example and the prototype. This paper is a summary of the mathematical advancements in capturing the framework of concepts within the prototype theory and the interplay between them. The authors developed an approach called the State Context Property (SCoP) formalism. They used participants to assign “membership weights” and “typicalities” to certain concepts and derived equations to show this likeness. Advanced quantum mechanics were utilized to further assess these relationships. This paper was interesting as it attempted to mathematically distill the many variables that goes into defining and quantifying what appears to be an inherent relationship within human language. It also showed modern day application to a learning theory that has been around for decades.

Bordage G, Zacks R. The structure of medical knowledge in the memories of medical students and general practitioners: categories and prototypes. Med Educ. 1984 Nov;18(6):406-16⁴

This paper conducted four experiments on preclinical medical students vs experienced general practitioners: 1) “to determine whether the concept of prototypes is applicable to the structure of selected categories of medical disorders as stored in physician memory,” and 2) “to describe to influence of clinical experience on these structures.” This study finds that Prototype view and memory of categories of disease were found in both the preclinical medical students and experienced doctors despite a disparate amount of training. This paper further suggests that medical educators should design medical school curriculum with Prototype theory in mind.

Papa FJ, Li F. Evidence of the preferential use of disease prototypes over case exemplars among early year one medical students prior to and following diagnostic training. Diagnosis (Berl). 2015 Dec 1;2(4):217-225⁶.

Diagnostic accuracy is difficult with the ill-defined nature of human diseases when individuals can have different signs and symptoms for the same disease process. The authors conducted studies on first year medical students through the use of Exemplar and Prototype theories (System I thought processing) to formulate a training exercise in order to improve their diagnostic accuracy and also to determine if Exemplar or Prototype theory is used preferentially for diagnosis. The authors conclude that the training exercise improved the students’ diagnostic acumen and found that they preferentially used Prototype over Exemplar theory for diagnosis

Limitations

One of the limitations of this theory pivots around the idea that there is not a defining characteristic that unifies a particular family of concepts. This can make the associations seem nebulous and ill-defined. Secondly, the theory has limitations in that the organization is individual-specific and sometimes even culture-specific⁹. For example, asking someone to categorize various fruits might be different in Africa compared to Northern Europe. Or, alternatively, categorizing various types of clothing would be different in India and in Brazil. Another limitation includes the requirement for a shared, minimal foundation of knowledge. If the original properties of an idea or concept aren’t agreed upon, it will not be possible to link them through groups using prototype theory. For example, in the initial vignette, if the intern did not know what shock was, then there would be no initial starting point from which to break shock down further. Another educational theory would be needed first. Also for orphan diseases that are very unusual, it would be difficult to come up with a diagnosis when it’s so dissimilar to a set prototype.

Part 3: The Denouement

The intern is overwhelmed by caring for the sick patient and trying to come up with other causes of shock. Her attending reminds her of the other types of shock, and while septic shock might be the “prime” example of shock (due to high prevalence in clinical practice), there are characteristics of each of the other types of shock that make them all recognizable under the umbrella of shock. After the patient is stabilized, the intern has now learned to classify the other types of shock, but as she is most familiar with septic shock, it serves as the “prototype” of shock for her learning. She relates all other types of shock to this example, and notes their differences and similarities. This allows her to learn additional concepts of shock by using a pre-existing framework. As her attending, you determined her “prototype” for a clinical concept to assess the basis of her understanding as the starting point for the other types of shock. This can help solidify the intern’s understanding by starting with a concept the intern is familiar with and expanding on related concepts.

Don’t miss the eighth post in the series, coming out Tuesday, March 31, 2020!

PLEASE ADD YOUR PEER REVIEW IN THE COMMENTS SECTION BELOW

References

1. Zadeh LA. A note on prototype theory and fuzzy sets. Advances in Fuzzy Systems — Applications and Theory Fuzzy Sets, Fuzzy Logic, and Fuzzy Systems. 1996:587-593. doi:10.1142/9789814261302_0027.

2. Aerts D, Broekaert J, Gabora L, Sozzo S. Generalizing Prototype Theory: A Formal Quantum Framework. Frontiers in psychology. 2016;7:418.

3. Margolis E. Concepts: Core Readings. Cambridge Mass.: MIT Press; 2000. 390

4. Bordage G, Zacks R. The structure of medical knowledge in the memories of medical students and general practitioners: categories and prototypes. Medical Education. 1984;18(6):406-416. doi:10.1111/j.1365-2923.1984.tb01295.x

5. Cognitive Psychology and Cognitive Neuroscience/Knowledge Representation and Hemispheric Specialisation. Wikibooks.

6. Papa FJ, Li F. Evidence of the preferential use of disease prototypes over case exemplars among early year one medical students prior to and following diagnostic training. Diagnosis. 2015;2(4):217-225. doi:10.1515/dx-2015-0024.

7. Eleanor Rosch. Wikipedia. https://en.wikipedia.org/wiki/Eleanor_Rosch#Categorization_and_prototype_theory. Published May 21, 2019. Accessed July 24, 2019.

8. Rosch EH. Natural categories. Cognitive Psychology. 1973;4(3):328-350. doi:10.1016/0010-0285(73)90017-0.

9. Geeraerts, Dirk. (2016). Prospects and problems of prototype theory. Diacronia. 10.17684/i4A53en.

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