Crossing Cognitive Chasms With P-prims

Crossing a cognitive chasm . . .

Apparently, roughly 10% of humans still believe that the Earth is larger than the Sun. Do they believe this because they haven’t been properly educated? Possibly. Do they believe this because they’re stupid? Probably not.

In fact, the most likely explanation is that the individuals concerned just haven’t thought that much about it. The Earth looks big; the Sun looks like a small disc in the sky; ergo, the Sun is smaller than the Earth.

The individuals are relying on what Andrea diSessa (1988) would call a phenomenological primitive or p-prim: “These are simple abstractions from common experiences that are taken as relatively primitive in the sense that they generally need no explanation; they simply happen.”

What is a p-prim (phenomenological primitive)?

A p-prim is a pattern of thought that is applied across a range of contexts. For example, the “Ohm’s Law” p-prim — the idea that increased “effort” invariably leads to a larger “outcome” and that increased “resistance” always yields a smaller “outcome” — is routinely applied not just to the domain of electrical circuits, but to the physical world in terms of pushing and pulling objects, and not least to the domain of psychology in the context (say) of persuading a reluctant person to perform an action.

Examples of other p-prims would include:

  • The “Father Dougal” p-prim: things that look small really are small; large things always look bigger than small things.
  • The “More Is Better” p-prim: that more of any quantity is invariably better than a smaller amount.
  • The “Dynamic Balance” p-prim: equal and opposite competing “forces” or “influences” can produce an equilibrium or “static outcome”.

P-prims are not acquired by formal teaching. They are abstractions or patterns extracted from commonplace experiences. They are also, for the most part, primarily unspoken concepts: ask a person to justify a p-prim and the most likely answer is “because”!

Also, p-prims exist in isolation: people can easily hold two or more contradictory p-prims. The p-prim that is applied depends on context: in one situation the “Ohm’s Law” p-prim might be cued; in another the “Dynamic Balance” p-prim would be cued. Which p-prim is cued depends on the previous experience of the individual and the aspects of the situation that appear most significant to that individual at that particular time.

The KIP (Knowledge in Pieces) Model

diSessa integrates these p-prims (and many others) into a “Knowledge in Pieces” model:

[I]ntutive physics is a fragmented collection of ideas, loosely connected and reinforcing, having none of the commitment or systematicity that one attributes to theories.

The model is summarised more poetically by Dashiell Hammett (quoted by diSessa):

Nobody thinks clearly, no matter what they pretend. Thinking’s a dizzy business, a matter of catching as many of those foggy glimpses as you can and fitting them together the best you can. That’s why people hang on so tight to their beliefs and opinions; because, compared to the haphazard way in which they arrived at, even the goofiest opinion seems wonderfully clear, sane, and self-evident. And if you let it get away from you, then you’ve got to dive back into that foggy muddle to wangle yourself out another to take its place.

— Dashiell Hammett, The Dain Curse

So, for example, a person might respond to the (to them) out-of-left-field question of “Which is bigger: the Earth or the Sun?” by simply selecting what seems to them a perfectly appropriate p-prim such as the “Father Dougal” p-prim: the Sun looks like a small disc in the sky therefore it is smaller than the Earth. It is important to note that this process often happens without a great deal of thought. The person reaches into a grab-bag of these small units of thought and takes hold of one that, at least at first glance, seems applicable to the circumstances. The person is simply applying their past experience to a novel situation.

Picking Your P-prim

However, as Anne Nelmes (2004) points out, the problem is that often the wrong p-prim is cued and applied to the wrong situation. As science teachers, is there a way that we can encourage the selection of more suitable p-prims?

Nelmes believes that there is:

Analogy has long been used to aid understanding of scientific concepts, both in and out of the classroom. Rather than trying to overtly change the misconception into the scientific conception, it may be as, or more, effective and certainly less time consuming to cue the right idea using analogy on a very low key level, without the pupils even realising that an analogy has been used. The idea of cueing correct ideas comes from work done by diSessa and others on p-prims (phenomenological primitives). These are small knowledge units which are cued to an active state to explain phenomena.

It is hoped the correct p-prim will be cued by use of the analogy and, if cued repeatedly, will strengthen.

One example presented by Nelmes that I find quite persuasive is in the context of students’ difficulty in accepting that good absorbers of heat radiation are also good emitters of heat radiation. A matt black surface will absorb a substantial fraction of the infrared radiation falling on it; however, matt black surfaces are also the most effective emitters of infrared radiation.

aborbers emitters

This seems a concept-change-too-far for many students; particularly as it often follows hard on the heels of good conductor = poor insulator and good insulator = poor conductor. Students find it hard to accept that a substance that is good at one thing can also be good at its opposite.

Nelmes suggests cueing a more appropriate p-prim for this context by the use of low key analogies such as:

  • Effective communicators are good at taking in information and good at giving out information.
  • Effective netball players are good at throwing the ball and catching the ball.

Nelmes’ research suggests that the results from such strategies may be modest but are generally positive. One telling example is the fact that many student answers featured “you” as in “I think this because when you are good at something, radiating, you are usually good at the other, absorbing heat.”

As Nelmes notes, the use of the personal pronoun in such answers suggests that students had, perhaps, absorbed the bridging analogy unconsciously.

Be that as it may, I think the p-prim and bridging analogy strategy is one I will be attempting to add to my teaching repertoire.


diSessa, A. A. (1988). Knowledge in pieces. In G. Forman & P. B. Pufall (Eds.), Constructivism in the computer age (pp. 49-70). Hillsdale, NJ, US: Lawrence Erlbaum Associates, Inc.

Nelmes, A. (2004). Putting conceptions in their place: using analogy to cue and strengthen scientifically correct conceptions.

11 thoughts on “Crossing Cognitive Chasms With P-prims

    • Professor Taboo May 31, 2018 / 2:34 pm

      Hahahaha! Miss Ironfist, I was thinking along the same lines… like those side-mirrors on vehicles? Men love, love, LOVE looking in them for OBVIOUS reasons. We really like them in our bathrooms when stepping out of the shower!
      “Objects in Mirror May Appear Larger Than They Are”! ๐Ÿคฉ

      • Miss Ironfist May 31, 2018 / 10:34 pm

        PT! I am dying ๐Ÿ˜น๐Ÿ˜น๐Ÿ˜น

  1. Adam May 30, 2018 / 9:08 pm

    I enjoyed this E – thanks ๐Ÿ™‚

    I’d only add a couple of things, first that I think it is likely that those 10% of people who think the Earth is bigger probably are less intelligent on average. Would be interested to see data on that.

    I think you would like Shtulman’s ScienceBlind. It’s a cornucopia of studies and approaches and a lot of it is dedicated to opposing the idea that “[I]ntutive physics is a fragmented collection of ideas, loosely connected and reinforcing, having none of the commitment or systematicity that one attributes to theories” in the sense that actually people do have well developed “primitive” (to use DS’s word) systems for conceptualising the world.

    Also to totally push this in a completely different direction Alvin Plantinga’s Warranted Christian Belief spends a lot of time talking about beliefs that are just “apparent”, and are not based on any kind of conscious thought. If you can get hold of a copy you might like it!

    • e=mc2andallthat June 3, 2018 / 2:17 pm

      “10%” is very much an “guesstimate”, but the I think the number got into my head from

      I think it’s very likely that our p-prims might fit together into a more coherent system — after all, if human beings have managed to survive for a million years or so, our instinctive “mental models” must have some utility in interacting with the environment.

      I think the intuitive physics “fragmented collection” is in comparison with a mature, organised science like Physics — where many minds have worked co-operatively over many years to ensure coherence and consistency over a much wider range of scales and physical conditions than ancient humans had access to (or maybe were interested in)

    • e=mc2andallthat June 3, 2018 / 2:39 pm

      I think “primitive” is not used in any pejorative way but rather in the sense of “unprocessed”, perhaps. But I think that what yourself and DS mean as well.

      I’ve heard of Plantinga, of course, but I haven’t read his work. Perhaps after I’ve finished Gottileb’s “The Dream of Enlightenment” (which I think is rather good).

  2. Professor Taboo May 31, 2018 / 2:42 pm

    Really enjoyed this post E=mc2 (G). Since I have a long background in psych-therapy โ€” as a worker-employee that is! ๐Ÿ˜‰ โ€” I MUST borrow this term โ€œP-Primโ€ and the Dashiell Hammett quote is so very true!

    Thank you again Sir for this delightful post. ๐Ÿ‘๐Ÿ‘

  3. grahamperrin63 June 2, 2018 / 5:38 pm

    Anyone who can get Father Ted and Physics into the same article is my kind of physicist.

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