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Meenal Sharkey; Mary Bing; Kimberly Schertzer; and Anne Messman
Authors: Meenal Sharkey, MD FACEP, Mary Bing MD, MPH, Kimberly Schertzer, MD
Editor: Anne Messman, MD, MHPE
A Case
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 she has difficulty coming up with other types of shock (e.g. hypovolemic, cardiogenic, neurogenic). The attending is wondering how best to utilize this situation as a teaching opportunity for the intern to learn other types of shock.
Overview
From the field of Cognitive Science, prototype theory is based on a conceptual organization for categorizing various items based on common features. A prototype is “an original model on which something is patterned.”(Merriam-Webster Dictionary) The features of a prototype are not necessarily defining features, but more of a resemblance that can be related to all the items within the family. If a prototype were placed in a family tree, it would be at the top and everything would descend from that prototype. 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, some items resemble a “prototype” more than others. There is not usually a single 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 grouping.2 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 rather than a definitive diagnosis. For example, a patient might complain of a 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 concept of disease categories in order to facilitate the learning and problem-solving process in clinical decision-making within medicine.4
Main Originators of the Theory
Eleanor Rosch
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 takes 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. 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; mathematical quantification was used to define “data on conceptual combinations.” This application attempted to quantify the “relatedness” of various concepts that were radially related based on the prototype theory.
Modern takes on this Theory
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.
Other Examples of Where this Theory Might Apply
- Relating various treatment plans to the “most common” presentation.
A stable patient with atrial fibrillation and rapid ventricular response with unknown onset can be managed with treatment of the underlying cause and medication such as calcium channel blockers, beta-blockers, or possibly digoxin. Extrapolating from this as the “prototype”, a stable patient with atrial fibrillation and rapid ventricular response with known onset can be managed with synchronized cardioversion. Conversely, an unstable patient with atrial fibrillation and rapid ventricular response can also be managed with synchronized cardioversion but with additional risk for stroke and the need for possible medical management afterwards. This 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. - Speed up diagnostic processes
In the clinical setting, the prototype theory (with semantic knowledge) can aid in the speed of retrieval of the information for illness scripts. This is related to how we categorize various illnesses upon initial evaluation and may have implications for how we recognize a similar/dissimilar patient presentation and fit it within a disease category.
Limitations of this Theory
One limitation of this theory is related to the lack of defining characteristic that unifies a particular family of concepts. This can make the associations seem nebulous and ill-defined. Secondly, the organization of concepts is specific to an individual and sometimes even specific to a culture.9 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. Also for diseases that are very unusual or rare, it may be difficult to come up with a diagnosis when it’s so dissimilar to a set prototype.
Returning to the case…
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.
References
- 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.
- Aerts D, Broekaert J, Gabora L, Sozzo S. Generalizing Prototype Theory: A Formal Quantum Framework. Frontiers in psychology. 2016;7:418.
- Margolis E. Concepts: Core Readings. Cambridge Mass.: MIT Press; 2000. 390
- 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.
- Cognitive Psychology and Cognitive Neuroscience/Knowledge Representation and Hemispheric Specialisation. Wikibooks. Available at: (https://en.m.wikibooks.org/wiki/Cognitive_Psychology_and_Cognitive_Neuroscience/Knowledge_Representation_and_Hemispheric_Specialisation) Accessed January 11, 2022.
- 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.
- Eleanor Rosch. Wikipedia. Available at: https://en.wikipedia.org/wiki/Eleanor_Rosch#Categorization_and_prototype_theory. Published May 21, 2019. Accessed July 24, 2019.
- Rosch EH. Natural categories. Cognitive Psychology. 1973;4(3):328-350. doi:10.1016/0010-0285(73)90017-0.
- Geeraerts, Dirk. (2016). Prospects and problems of prototype theory. Diacronia. 10.17684/i4A53en.
Annotated Bibliography
1. Aerts D, Broekaert J, Gabora L, Sozzo S. Generalizing Prototype Theory: A Formal Quantum Framework. Frontiers in psychology. 2016;7:418.
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 go 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.
2. 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):406-16
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.
3. 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):217-225
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.
