Re-Thinking Expertise: The Skill Portfolio Account

I suggest that we abandon our current unitary concept of experts. Too often, when we think of experts we think of an undifferentiated quality — someone is an expert or isn’t. Or we postulate stages of moving from novice to expert. That’s not good enough.

In contrast to a unitary concept of experts, a Skill Portfolio account identifies separate skills that experts possess. Experts blend these skills as needed, but the skills themselves are fairly independent — a portfolio of skills. Not all experts will have each of these skills, or need them. The skills describe what experts can do and what they know, as opposed to the outcomes of applying the skills.

Kahneman & Klein (2009) discussed the concept of fractionated expertise, drawing on previous work by James Shanteau. “For example, auditors who have expertise in “hard” data such as accounts receivable may do much less well with “soft” data such as indications of fraud.” (p. 522). In this essay, I am expanding on this idea of fractionated expertise.

We can distinguish five general types of skills that experts may have: Perceptual-motor skills, Conceptual skills, Management skills, Communication skills, and Adaptation skills. These are not components of expertise. Some skills may be relevant in one domain but not another. And they are reasonably independent.

First, Perceptual-motor skills. Some aspects of perceptual-motor skill constitute tacit knowledge: pattern recognition, perceptual discrimination, motor skills and the use of tools. Think of the way dentists use mirrors to repair cavities. A dentist can drill skillfully because the perceptual-motor skills of mirror handling have been highly automated.

Second, Conceptual skills. These include our mental models. For example, the dentist has a conceptual model of how the various materials in a tooth (enamel, dentine, prior filling materials, nerve roots) behave during the drilling process, along with a mental model of how teeth must be configured to be successfully filled with the epoxy or other materials. Our mental models enable us to see the big picture in a situation, diagnose the causes of problems, and anticipate future states. Experts also have mastered the Standard Operating Procedures and Best Practices but their mental models are rich enough to indicate when the SOPs and Best Practices need to be modified or abandoned. Borders, Klein & Besuijen (2019) have described a Mental Model Matrix that goes beyond a representation of how things work and includes limitations and flaws, as well as workarounds.

Third, Management skills. Continuing the dental example, the dentist knows how to manage the assistant and the patient during the process, including knowing how the assistant's training will shape his or her behavior. Each patient will behave differently, as will different assistants, but the dentist has the management expertise to make the situation graceful regardless of emergent issues like patient anxiety, training gaps in the assistant, etc.

Fourth, Communication skills. Dentists and their assistants have developed carefully choreographed routines for managing routine procedures, and can adapt these routines when they encounter new situations. Communication skills are really tested when the routines break down, like encountering a novel configuration during a root canal. The team members have to explain things to each other and direct each other efficiently and unambiguously.

Fifth, Adaptation skills. Ward et al. (2018) have asserted that the essence of expertise is the ability to adapt. This claim is that experts are faster to adapt to changing conditions (such as COVID-19) than non-experts. Ward et al. provide evidence that adaptation can be improved by training, and offer recommendations for such training. The concept of adaptive skill shows why expertise does not become obsolete — just the opposite, it becomes the basis for improvising and making discoveries.

These five general skills are identified on several criteria: First, they are acquired through experience and feedback, as opposed to being natural talents. Second, they are relevant to the tasks people perform, and therefore the set of skills will vary by task and domain. Third, superior performance on these skills should differentiate experts from journeymen.

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The skills will vary for different domains and tasks. Our focus should be on the most important sub-skills for that domain. Otherwise, it is too easy to have an ever-expanding set of skills to contend with. In some domains, one or more of these general skills may not apply at all. And, as Kahneman and Klein, and Shanteau note, people may be experts in some aspects of a task but not others. (Here is a link to a fuller discussion of the Skill Portfolio account, using COVID-19 as an example.)

There will undoubtedly be disagreements about which skills to include in a Skill Portfolio account, and what level to use in describing a skill, and how distinct some of the skills are from others, and which skills are relevant within a domain and for a given task. We are not dealing with a Table of Elements in chemistry. I expect that these debates will be informative.

The Skill Portfolio account illustrates how shallow it is to claim that new developments will make expertise obsolete. Such claims rely on the unitary model of experts instead of a differentiated model.

What is becoming obsolete is the description of expertise that is grounded in the study of domains that are relatively stable.