Sunday, March 01, 2020

Bloom (1913-1999) - Taxonomy of learning… not a hierarchy…

One famous paper by Benjamin Bloom, The 2 Sigma Problem, compared the lecture, formative feedback lecture and one-to-one tuition. Taking the straight lecture as the mean, he found an 84% increase in mastery above the mean for a formative approach to teaching and an astonishing 98% increase in mastery for one-to-one tuition. Google’s Peter Norvig famously said that if you only have to read one paper to support online learning, this is it. In other words, the increase in efficacy for one-to-one because of the increase in on-task learning is immense. This paper deserves to be read by anyone looking at improving the efficacy of learning as it shows hugely significant improvements by simply altering the way teachers interact with learners. Online learning, in the widest sense of the word promises what Bloom called ‘one-to-one learning’, whether it’s through self-paced structured learning, scenario-based learning, simulations or informal learning.

Bloom’s taxonomy

However, Bloom is far better known for his hugely influential classification of learning behaviours and provided concrete measures for identifying different levels of learning. His taxonomy includes three overlapping domains:
Cognitive (knowledge)
Psychomotor (skills)
Affective (attitude)
It was devised to assist teachers to classify educational goals and plan and evaluate learning experiences. Unfortunately, this is about as far as most people get. They rarely dig deeper into his further six levels in the cognitive, six different aspects of psychomotor skills and his less useful, three types of affective.

Cognitive domain (knowledge-based)

In the original version of the taxonomy, the cognitive domain is broken into the following six levels of objectives:
In the 2001 revised edition of Bloom's taxonomy, the levels are slightly different:

Create (rather than Synthesise)
Note that there is no sense of higher and lower here, as they are often represented in diagrams.

Psychomotor domain (action-based)

Skills in the psychomotor domain describe the ability to physically manipulate a tool or instrument like a hand or a hammer. Psychomotor objectives usually focus on change and/or development in behavior and/or skills.

Affective domain (emotion-based)

Skills in the affective domain describe the way people react emotionally and their ability to feel other living things' pain or joy. Affective objectives typically target the awareness and growth in attitudes, emotion, and feelings.


Bloom published his now famous taxonomy of learning in 1956. Few realise that this taxonomy is now over 60 years old. There have been lots of taxonomies since then that slice and dice, many variations on existing categories. Indeed we've had dozens of taxonomies that sliced and diced in all sorts of ways. We've had Biggs, Wills, Bateson, Belbin and dozens more. We seem to have got stuck in the Bloom taxonomy. To be fair there have been good revisions, taking the knowledge nouns and unpacking them into verbs Anderson and Krathwohl (2001).
The problem with taxonomies is their attempt to pin down the complexity of cognition in a list of simple categories. In practice, learning doesn’t fall into these neat divisions. It’s a much more complex and messier set of cognitive processes, so attention has shifted to how learning meshes with memory and techniques that improve organisation, chunking, encoding, practice and recall.
Another danger is that instructionalists, like Gagne, take these taxonomies and attempt to design learning that matches these categories, destroying much of the more useful approaches which an understanding of brain science brings; such as cognitive overload, working memory limitations, top-down processing and so on. Learning theory has moved on in terms of a more detailed understanding of memory, which has put everything on a more empirical and scientific basis.


We have Bloom to thank for addressing the basic but important issue in education – that group learning is not always better learning. He showed that formative feedback and one-to-one tuition are indeed powerful amplifiers of learning. Bloom was also the first to really establish a solid, working taxonomy of learning, had to have his theories extended, as people realised that the tripartite classification was too narrow. The cognitive, psychomotor and affective distinction is still widely used today, which is either a testimony to Bloom’s vision, or a tendency for the training world to become stuck in old models. His taxonomy was at least a start, which ultimately led to a more professional approach to instructional practice. Unfortunately, some like to represent Bloom’s taxonomy in a pyramid suggesting, both implicitly and sometimes explicitly, that knowledge, at the bottom, is inferior. It was never meant to be a hierarchy from lower to higher. Bloom meant no such thing.


Bloom, B.S. (Ed.) (1956). Taxonomy of educational objectives: The classification of educational goals: Handbook I, cognitive domain. Longmans, Green.
Guskey, T. R. (2005).Benjamin S. Bloom: Portraits of an educator. Lanham, MD: Rowman & Littlefield Education.

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