Ask someone to describe a major organisational change they lived through.
They won't give you a balanced assessment. They won't walk you through the timeline, weigh up the wins against the losses, and arrive at a measured verdict.
They'll tell you about the moment it felt like everything was falling apart. And they'll tell you how it ended.
That's it. If enough time has passed...that'll be the whole snapshot.
There's a name for this, and applying it deliberately might be the most underrated lens in change leadership.
The Peak End Rule — and why Daniel Kahneman complicates project planning.
The Peak End Rule comes from the work of Daniel Kahneman — Nobel laureate, author of Thinking, Fast and Slow, and the closest thing behavioural science has to a GOAT.
The finding is deceptively simple: we don't remember experiences as averages. We remember them by their emotional peak — the most intense moment, positive or negative — and disproportionately by how they ended.
Everything in between? Duration, effort, the months of steady progress? Over time...largely deleted. At best, skewed and imperfect in memory recall.
Kahneman and his colleagues described it this way: “People construct and evaluate a representative moment and use the evaluation of that moment as a proxy for the entire episode. The peak and the end are given special weight.”
To be precise about what this is and isn't: the Peak End Rule is NOT a claim that complex change reduces to only two moments. It's a specific finding about how episodic memory works — how the brain encodes a 'bounded experience' in retrospect.
The months of careful work in the middle matter enormously for delivery. The question is whether they're what gets remembered. The research suggests, on the whole...it is not.
Try it yourself. Think about a holiday you loved. You probably recall a general warmth about the trip, two or three vivid moments that made it (“take me back!”), and something about how it ended — the last meal, the drive home, the feeling of landing back in familiar territory. You probably can't accurately recall how long you were away. The duration has collapsed.
We discount the average meal on the second night, the 'decent' activity we paid a bit extra for, the days that simply met expectations.
Now here's the extension of this thought to pay attention to: your people are doing exactly the same thing with every change programme you've ever run.
What this means for the programmes you're running right now.
Most change programmes are designed around the middle.
The middle is where the work is. The stakeholder engagement. The training rollout. The comms cadence. The governance forums. All legitimate. All necessary. All largely forgotten.
Meanwhile, two moments are being written into organisational memory whether they were planned or not:
The peak — the emotional high water mark of the programme. This might be positive: the day the system went live and actually worked. The moment a sceptical leader became an advocate. The first time a team reported that the new way was genuinely better than the old.
Or it might be negative: the day the restructure was announced badly. The town hall where a leader couldn't answer a basic question. The go-live that went wrong in front of everyone who'd been told it was fine.
The end — how the programme concluded. Was there a proper close? Did leadership acknowledge what people went through? Did the new way of working actually embed, or did the project team disappear and leave people to figure it out? Heaven forbid...were there actually lessons learned?!
Given our disproportionate memory, it's worth asking whether these two moments are being designed actively — or simply left to chance.
The negative peak problem.
One thing Kahneman's work makes clear: negative emotional peaks count at least as much as positive ones. Often more.
In my experience, the most common unplanned negative peak in a change programme isn't a dramatic failure. It's a specific, quiet moment of disrespect.
The town hall where the Executive talked for forty minutes and took no questions, dodged the one which would have helped everyone 'take a breath'. The announcement that (perhaps accidentally, thanks to layers of bureaucracy) landed in inboxes at 4:55 on a Friday. The all-staff video update that used the word “exciting” four times and explained nothing. The moment people realised that the decision had already been made and the “consultation” was theatre.
These moments lodge. They become the story people tell about the programme. They spread through the informal networks — through your Quiet Influencers, in the direction you don't want — and they shape how the next change lands before it even starts.
You can deliver a technically excellent programme and have it remembered as a shamozzle...because the peak moment was mishandled.
The inverse is also true.
I've watched a genuinely difficult change (think: restructure, a system replacement, a culture shift) be remembered with something approaching fondness, because the leader handled one moment with unusual honesty and care. The sponsor named what was hard and without spin. The leading team delivered the most difficult 'win' first up, to build trust.
Heck, even a humble but sincere additional 'social event' as a thank you for “digging in”...has been what former colleagues and I reminsced on years later.
That peak became the memory, and it carried the whole programme.
The ending problem is worse.
If negative peaks are underestimated, endings are almost completely ignored.
Justin Balaski at IdeaLeap has made the point better than anyone I've come across: go-live is not the finish line. And I'll keep saying it until organisations stop treating it as the end of the change. It isn't. It's roughly the halfway point of the human side of any transformation.
The ending of a change programme, in the Peak End Rule sense, is the period when people are forming their lasting impression. Are the new behaviours sticking? Does anyone still care? Has leadership moved on to the next thing and left people mid-transition?
The most common ending I see in corporate change programmes: the project team disbands, the steering committee stops meeting, and three months later someone asks “how's the change going?” to an organisation that's quietly drifted back to its old habits because nobody designed the new ones to last.
That ending gets remembered — even if it's underwhelming. And it shapes how much discretionary effort people give the next change that gets announced.
What designing the peak and the end actually looks like.
This isn't about manufacturing artificial moments or staging emotional set pieces. People can smell inauthenticity from a long way away, and a 'fake peak' is worse than no peak at all.
It's about intentionality — asking the question most programme plans never ask: what do we want people to remember about this?
For the peak, that means finding the moment of genuine human significance in the programme and making sure it's handled with the care it deserves. It might be a milestone celebration that actually acknowledges what people went through to get there. It might be a leader saying something real in a moment of difficulty rather than retreating to corporate language. It might be giving the quiet influencer who carried this programme their rightful recognition.
For the ending, it means designing the close as deliberately as you designed the launch. A proper acknowledgement of what changed and what was lost. Evidence that the new way is working, for the front line that needs it to. A clear signal that the organisation is paying attention to whether the change actually stuck...not just whether the project delivered on time.
Flyvbjerg would remind you to plan slow and act fast; the Planning Fallacy is your enemy. An antidote to that is designing the finish intentionally.
The last impression is disproportionately powerful, so treat it that way.
The practical question.
Before your next programme review, consider two questions:
What is the peak emotional moment of this change going to be? Is it being designed — or left to chance?
How and when does this really end? Will people feel that the organisation saw them through it, say six months after go-live?
If those questions aren't on your programme review agenda, there's a reasonable chance the Gantt chart has more influence over your change design than the psychology does.
In the long run, your programme will be remembered for two moments; It's worth knowing which two they are.
The Peak End Rule was identified by Daniel Kahneman and colleagues. His book Thinking, Fast and Slow is the seminal text that reshaped how a generation of leaders, researchers and practitioners think about human decision-making. If you haven't read it, start there. A nod also to Justin Balaski at IdeaLeap — who has made the “go-live is not the finish line” point better than anyone I've come across in this profession.