Stir cornflour into water until it is thick and milky, then hit the bowl with your fist. It behaves like a solid: your hand stops dead and the surface barely marks. Now lower the same hand slowly into the same bowl and it sinks in without a fuss. Same mixture, same hand, same effort. The only thing that changed is how fast the hand moved. It takes two minutes at the kitchen table, and it explains much of what leaders call resistance to change.
Physicists call this shear thickening, and cornflour in water is its best-known case. Heinrich Jaeger of the University of Chicago explains that a slow lift lets your hand out, that a quick jerk makes the mixture act like a solid, and that once you stop forcing it the mixture goes back to liquid.
I think people often behave the same way. The same demand, applied slowly, flows; applied suddenly, it hardens. Leaders spend their effort on how much pressure to apply: how firm, how urgent, how senior the sponsor. The bowl says the rate matters more. I arrived at this model on my own this week, then found that Venkatesh Rao uses oobleck to think about discourse in the age of AI, so the image is not entirely mine. The rule I draw from it for leaders is: push slowly, not softly. Keep the direction fixed and lower the speed.
When feedback lands as a hit
In 1996, Avraham Kluger and Angelo DeNisi pooled 607 effect sizes from studies of feedback. It improved performance on average, but more than a third of the interventions made performance worse. Their explanation: the effect falls as attention moves from the task to the self. A comment that arrives suddenly and heavily does exactly that. The listener stops asking how do I fix this? and starts asking am I in trouble?
Psychologists have a name for one version of the stiffening, reactance, a theory Jack Brehm proposed in 1966: a threat to your freedom of choice produces an urge to regain it. Reactance explains why people stiffen. It does not tell a leader which dial to turn. The bowl does.
An avalanche of help
Teams show it often. People clam up when others try to help with an avalanche of data, ideas, alternatives, and documents. The help is generous and the content may be good. The rate is a hit, and the silence that follows looks like agreement or disengagement.
Size matters here in the way the bowl predicts. Brown and Jaeger’s review is about concentrated suspensions, the packed ones where the grains jam. My inference for teams, and it is only that: the fuller a team’s plate, the lower the rate that tips it. Take a team at the top of the two-pizza range: Jeff Bezos put the rule as a team no larger than can be fed by two pizzas, which I read as five, give or take two. Seven people have 21 pairs who can misunderstand each other. Add two people and it has 36: 29% more people, 71% more links, which is the arithmetic behind Brooks’s Law. A team that has just grown is a fuller bowl, and a push it absorbed last quarter can land as a wall this one.
Automate it, then announce the next thing
AI adoption is the live case. A step gets automated and it works. Before anyone has enjoyed that, the next step is announced. The reaction is closer to my job has to stop changing for a second than to fear of losing it, and I have seen it in engineering and in content production. People stop asking questions and just check out.
In Why AI Adoption Really Stalls I argued that people hold back because AI threatens who they think they are. The rate of the push decides whether that threat becomes a wall. If adoption is the CPTO’s real job, pace is part of the job. This is a different issue from the one in The AI Acceleration Trap, which is about the total load an organisation can absorb: here it is the manner of a single demand.
Three changes, in the order I would make them:
- Name the direction, then slow the rate. One change at a time, sized to what the team can take, instead of a mandate, a dashboard, and a training programme in the same fortnight.
- Read what comes back. Questions are flow. Silence and instant agreement are the wall.
- Take the force off, then ask what the person is protecting. Robert Kegan and Lisa Lahey call it a competing commitment, and it explains most of what looks like opposition.
The break that works
Relationships show the reversal most plainly. The Gottman Institute describes flooding: partners overwhelmed in conflict turn defensive or silent, and it advises a break of at least twenty minutes. The break takes the force off and the liquid comes back, while the argument itself waits.
Where the bowl misleads
People thin under pressure too. Ketchup runs faster the harder you shake the bottle, and a short deadline sharpens some people in much the same way. Cornflour has no memory; people do, and they stay hard for days after a push they did not deserve. Sometimes holding firm is the right response. The model describes a tendency, not a law, and it fits the first reaction better than the relationship.
If you want movement, ask before each push how fast you are moving, and what will happen to the force when it meets a wall. Next time someone goes rigid in front of you, take your hand off before you decide what they are like.
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