Learning by reward
Nobody tells the learner the right answer, only how well it did. How that one number teaches, and where it misleads.
- 9min read
- 29questions
Listen to the episode
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Nobody tells the learner the right answer, only how well it did. How that one number teaches, and where it misleads.
Listen to the episode
0:00 / 10:01
You keep more from recalling something once than from reading it twice.
In a 2006 experiment, students read one passage twice, and read another once and then tried to recall it. A week later they remembered 42% of the first and 56% of the second. So every article here comes with questions, and the EdenMind app brings each one back just before you’d forget it.

Labels are slow and costly to make. So machines learned to set their own questions: group what is alike, rebuild what was squeezed, guess what was hidden.

Information is measured by how much a message surprises you, and a machine that learns to be less surprised by text learns a great deal about it.

Start from what you already knew, weigh the new clue, and end up exactly as sure as the evidence allows.

Vectors and matrices, the school maths that search engines, recommendations and every neural network quietly run on.

Some of the best-known stories about the mind met the simplest test in science: doing the study again.

One of psychology’s most famous lessons says a uniform can make a good person cruel. The full story is stranger, and it hands the responsibility back to the person.

One kind of thinking answers at once; the other checks, if it can be bothered.

When nearly everything in the shop costs more, the goods haven’t changed. The money has, because each unit of it now buys less.
Ibn al-Haytham told his reader to make himself an enemy of everything he reads.
He wrote it of Ptolemy, whom he admired, and asked the reader to suspect himself too. The pieces here are written in that spirit, for the readers who inherited it. Where scholars of the Muslim world shaped a subject, they are named for what they did: al-Kindī on breaking ciphers, the earliest account we have, or Ibn al-Nafīs on the route blood takes through the lungs, three centuries before Europe found it.
A cipher hides a message’s letters but not its patterns, and the patterns are what give it away.
8 min read
Attention, next-word prediction and scale — and the gap between sounding right and being right.
9 min read
Nobody writes the rules. A network of simple calculations tunes itself on examples until its answers come out right.
8 min read
Every clock is something that repeats at a steady pace, plus a way to count the repeats. The rest of the story is the hunt for something steadier.
9 min read
Lamps in a dark room, a tube on a ruler and a book of doubts — how one scholar rebuilt the science of sight.
8 min read
The doorknob zap and the lightning bolt are the same event at different sizes — meet the charge that runs the world.
9 min read
Water alone can’t lift grease or break open a flu virus. Soap does both, with a molecule that holds water at one end and grease at the other, and Nablus made it from olive oil and plant ash for centuries.
7 min read
The one element versatile enough to build diamonds, fuels, plastics — and you.
8 min read
One scale from battery acid to drain cleaner, and the truce called neutralisation.
8 min read
Every navigator needs a compass and a map. A young bird is born with its heading, but its map comes from experience.
8 min read
Nothing lives alone — how energy flows, matter cycles, and a web of life holds together.
8 min read
How oxygen reaches every cell you own — and the Muslim physician who first traced its path through the lungs.
8 min read
Repeat an action in the same place often enough, and the place starts doing it for you.
8 min read
We think of a test as a way to measure learning. Done well, it is one of the best ways to cause it.
6 min read
Memory fades along a curve. Coming back at the right moments bends it.
7 min read
Why a light bulb, a printing press and a television screen change people, whatever they carry.
8 min read
It’s easy to believe you knew an answer once you’ve seen it.
Most flashcard apps show you the answer and then ask you to mark yourself. In EdenMind you say it first and your phone marks it, allowing for an accent, a plural or a number said in words. Your voice never leaves the phone.









