Kittens. ‘Blue’. Situation Awareness. Human Factors. Can you join those dots!
In 1970, two Cambridge researchers, Colin Blakemore and Grahame Cooper, raised kittens in an unusual environment. From birth, the kittens spent their waking hours inside a cylinder painted with vertical stripes, wearing a collar that stopped them from even seeing their own bodies. Everything else was darkness. When the kittens were later tested, their visual cortex had wired itself around what it had been given: neurons responded to vertical edges and almost nothing else. Behaviourally, the kittens were, in the researchers' words, "virtually blind" to horizontal contours. Shake a vertical rod and they would chase it like any kitten. Turn the same rod horizontal and it stopped existing for them. They bumped into obstacles they should have seen, not because they were careless, but because their perceptual system had never been given the pattern to learn and refer back to.
We are not kittens, and nobody is raising divers in striped cylinders. But there is a human version of this, and we don’t need to test divers like lab rats. Anthropologists call it hypocognition: the state of lacking the concept you would need to recognise something that is right in front of you. Robert Levy coined the term after fieldwork in Tahiti, where he noticed that the local language had rich vocabulary for many emotional states but almost nothing for grief. Tahitians who had lost someone clearly experienced something, but without a concept to hold it, they struggled to make sense of what was happening to them. More recently, the psychologists Kaidi Wu and David Dunning have argued that hypocognition is everywhere: most of what we fail to notice, we fail to notice not because it is hidden, but because we have no mental category for it. It is the perceptual cousin of not knowing what you don't know.
The colour research makes the point more tangible and measurable. Russian has no single word for blue. It has two, and speakers must choose: goluboy for light blue, siniy for dark. When researchers tested Russian speakers against English speakers on colour discrimination tasks, the Russians were reliably faster at telling apart shades that straddled their linguistic boundary, and the advantage vanished when their verbal system was tied up with another task. I’m being specific about the claim: language does not create sight. Infants discriminate colours before they have words. What language does is sharpen discrimination at the boundaries it identifies, stabilise what we perceive so memory can hold it, direct attention toward distinctions that matter, and, crucially, make private perception transferable to someone else. So we don’t just have a perception issue, we also have a communication issue.
Teams don't share perception. They share categories.
A diver at twenty metres notices something. Their breathing rate has crept up, their trim has degraded slightly, the plan doesn’t feel as tight as it did on the surface. What message reaches the rest of the team? If the diver has no vocabulary for what they are sensing, the answer is usually nothing, or at best a vague "I don't know, something felt off" delivered in the debrief, where it dies for lack of anything to attach it to.
The perception happened, but the communication of it could not, because communication runs on shared categories, not raw experience.
This is the same reason the debrief of an untrained team so often collapses into generalities:
"we need to be more careful",
"keep a better eye on each other",
"communicate more".
These are not lessons we can learn from. They are the sound a team makes when it has experiences but no words. It is why we talk about being specific in debriefs, not applying generalities.
Now consider what happens when the team does have the words.
"I was task-fixated on the reel and dropped my scan."
"We drifted from the plan in small steps and none of them seemed worth mentioning."
"I noticed the deviation but didn't feel I could challenge it."
Each of these statements contains a named pattern: task fixation, drift, a failed challenge. Once named, the pattern can be recognised next time, discussed without blame, and looked for deliberately. Diane Vaughan's "normalisation of deviance" is the classic case: once she named the pattern in her analysis of the Challenger launch decision, people began recognising it in organisations a long way from NASA, and I have had this type of feedback during classes or conference presentations - you've give me the words to describe something I was observing but didn't know how to say it. The vocabulary is not the icing on the cake of learning - the vocabulary is what makes the learning possible, in the same way that goluboy and siniy make certain blues easier to tell apart.
This is what a shared mental model actually is at the working level: not a diagram in a manual, but an overlap in the categories two people use to carve up their understanding of the same dive.
What 'it's common sense' actually means
Which brings us to the phrase that quietly removes so many opportunities for learning. When an experienced instructor says, "it's just common sense", they believe they are describing the skill. Instead, what is happening is they are describing themselves!
What the phrase really means is: “I can no longer remember what it was like not to see this.”
The instructor's pattern library is so deeply ingrained that the patterns feel like properties of the world rather than products of their own history and associated sense-making. But if the ‘sense’ were genuinely ‘common’, students would arrive with it, and there would be nothing to teach. The fact that novices routinely miss what experts find obvious is not evidence that novices are careless, rather it is evidence that "obvious" is the feeling of a well-trained perceptual system, and the novice's system has not been trained yet.
Telling a student to use common sense is telling the kitten to watch out for the horizonal stool seat. The seat is right there, but the cognitive wiring to detect it is not.
This discrimination between perception and sense-making is important for instructor and student development because the instructor trainer/instructor's job is to decompose what has become automatic: to take a pattern they now perceive as a single obvious whole and break it back into nameable, teachable parts.
An instructor who cannot articulate what they are perceiving cannot teach it; they can only demonstrate it and hope. Some students will eventually build the patterns through raw exposure, the slow and expensive way. Language is the shortcut evolution gave us: it lets one person install a pattern in another without the other needing ten years of dives, or the near-miss that finally makes it vivid.
When the narrative is flawed, it's worse than no narrative
What if we just didn’t have no words, what if we had the wrong ones? Consider how situation awareness is often taught in diving: as a set of concentric circles. What's going on in your head, in your body, with your equipment, with your buddy, with the environment. Scan the rings, and you have situation awareness.
This approach is easy to remember, easy to draw on a whiteboard, and it does contain something useful: a prompt about where to direct attention. Unfortunately, it misses a critical factor. The concept describes where to look; it says nothing about what looking is for. It offers a snapshot but without the arrow of time that is so needed. Mica Endsley's model, from which the term largely derives, has three levels: perceiving the elements, comprehending what they mean, and projecting what they imply for the near future. The concentric circles stop at level one, maybe two. A student can scan every ring diligently, tick every domain, and still have no idea what happens next, because nothing in the model asks them to predict anything.
And prediction is the whole game. The experienced diver's "something isn't quite right" is not the product of scanning harder, it is a mismatch signal. Their mental model of the dive was generating expectations, educated (or uneducated) guesses e.g., gas pressure at this point, buddy positioned there, workload feeling like this, and then, at some point, the world stopped matching the forecast.
Unease is what mismatch detection feels like from the inside, that ‘bad gut feeling’ we sometimes feel when things aren’t quite right, and that arrives before the conscious mind can say what triggered it. I am sure you’ve felt this when you’re driving down the motorway/freeway and nearly miss the junction, noticing at the last minute.
The concentric circles cannot explain this experience, they cannot help a student develop it, and they cannot give them permission to act on it. Worse, when a student taught the circles is later surprised by an event, the available explanation is that they "lost situational awareness". This ‘explanation’ points at the individual rather than at the model they were given to refer to. A flawed narrative is worse than none, because it takes up a space in the brain that a better model would go.
Why this sets up next week’s learning topic
Everything above sits under this week's theme of communication, but the consequences are firmly in next week's topic - decision-making. Decisions are not made about 'now' or the 'past' - they are made on the perceived and projected future world. Gary Klein's research on how experts decide under pressure found little deliberate comparison of options; instead, experts recognise a situation as a type they have seen before, recover a workable response, and run it forward mentally to check it. The quality of that process depends entirely on the depth and breadth of patterns the operator (diver) is working from, and on how early the mismatch was detected.
The options we have underwater have a ‘shelf life.’ If you pick up the mismatch early, you have easy/’cheap’ choices: adjust, communicate, end the dive. Notice it late and you are choosing between 'expensive', potentially critical ones. Projection, the very level the concentric circles omit, is what buys the time in where we’ve still got an option to make. Remember, the clock can always make the decision for you.
What do I do with this?
Brief with expected states, not just plans, so that deviation becomes detectable and utterable: "at twenty minutes we should be at the junction with around 150 bar" gives everyone a forecast to compare against.
Teach that 'unease' is data, a pattern-match that has ahead of explanation, and build the psychological safety for someone to voice it without having to justify it first.
Ask projection questions in debriefs: not "what happened?" but "what did you expect to happen next, and when did the dive stop matching?"
Replace "be more aware" with named, observable behaviours that students can practise and you can assess.
The kittens never got to choose their vertical stripes. We do. Every precise term we give our students, every mechanism we explain instead of pointing at, every flawed model we replace with one that actually describes how noticing works, adds something that the students’ perceptual system can respond to, and therefore improve.
That is what teaching is - underneath everything else - deliberately wiring a world into view so we can recognise, monitor, adapt, and learn. Common sense is not where instruction starts - it is what good instruction leaves behind.
In Summary
Perception is trained, not given: Blakemore and Cooper's kittens were functionally blind to orientations they had never seen, and divers are functionally blind to patterns they have never had named. "It's common sense" describes the instructor's wiring, not the student's, and teaches them nothing about how to make improvements.
Flawed models are worse than missing ones: the concentric-circles version of situation awareness prompts scanning but omits projection, so it cannot explain, or develop, the "something isn't quite right" feeling that comes from expectation mismatch. Shared, specific vocabulary is the technology by which teams transfer perception, and early, well-named detection is what keeps cheap options open when the decision-making starts.
References
Blakemore, C., & Cooper, G. F. (1970). Development of the brain depends on the visual environment. Nature, 228(5270), 477–478. https://doi.org/10.1038/228477a0
Endsley, M. R. (1995). Toward a theory of situation awareness in dynamic systems. Human Factors, 37(1), 32–64. https://doi.org/10.1518/001872095779049543
Klein, G. (1998). Sources of power: How people make decisions. MIT Press.
Levy, R. I. (1973). Tahitians: Mind and experience in the Society Islands. University of Chicago Press.
Winawer, J., Witthoft, N., Frank, M. C., Wu, L., Wade, A. R., & Boroditsky, L. (2007). Russian blues reveal effects of language on color discrimination. Proceedings of the National Academy of Sciences, 104(19), 7780–7785. https://doi.org/10.1073/pnas.0701644104
Wu, K., & Dunning, D. (2018). Hypocognition: Making sense of the landscape beyond one's conceptual reach. Review of General Psychology, 22(1), 25–35. https://doi.org/10.1037/gpr0000126
