Peak–end rule
Etymology
Established by Daniel Kahneman and colleagues in the 1990s, including work with Barbara Fredrickson and a colonoscopy study with Donald Redelmeier showing that a longer procedure with a gentler ending was remembered as better. The name is literal: memory weights the "peak" of intensity and the "end," and largely ignores how long the experience lasted — a quirk Kahneman called "duration neglect."
noun · /PEEK END rool/
The tendency to judge an experience almost entirely by how it felt at its most intense moment and at its end, rather than by the sum or average of the whole thing.
What it names
It explains why a great trip with a miserable last day is remembered as bad, and why the shape of an experience matters more than its total.
Example
They closed the conference with a strong final speaker on purpose, betting the peak–end rule would make attendees forget the sluggish middle.
Related idea
Duration neglect is the flip side of the same finding — how long an experience lasted barely registers, which is why the peak and end dominate.