I am not a synaesthete and I wonder how other non-synaesthetes perceived the '5 vs 2' diagram. Even though I see all the digits in plain black, the triangle of 2s immediately stood out to me. The author writes:

'For me, four-leaf clovers are a different shape so they stand out in a clover patch very much like this. Unlike letters and numbers, however, I don't get a sense of color, it's more like a sense of movement.'

But even as a non-synesthete, I felt a sense of movement in the 2s, as if they were little swans swimming against the bevy of 5s. But I felt no such movement when looking at the photographs of clovers. I could only spot a few four-leaf clovers at a quick glance because the pale markings on them form a rough quadrilateral, so I was essentially spotting those shapes rather than the four leaflets themselves.

If this sort of topic interests you, I wrote an article earlier this year about number–colour–phoneme associations: https://susam.net/assoc.html

As I mentioned, I do not have synaesthesia, yet the associations between numbers, colours and phonemes are quite strong in my mind due to early exposure to CGA colours and mnemonic systems. For instance, I find it hard to think of the number 1 without thinking of blue or the phonemes /t/ and /d/, or to think of 4 without thinking of red or /r/. I have written more about it in the article linked above.

I've been able to find four-leaf clovers easily since I was a kid. Like the OP they seem to just "pop out" at me as I quickly scan the ground, but I do not have the same background with synesthesia.

Since four and five leaf clovers tend to grow in patches, I transplanted a patch I found and have kept it in a planter on my deck so that anyone who has never found a four leaf clover can find one!

I wrote about my lucky clover patch here: https://jherrman.com/four-leaf-clover-patch.html

How strange. I introduced clover to my lawn a few years ago for its nitrogen fixing properties, and since then have spent many idle minutes (probably adding up to hours) searching for four-leaf clovers.

I have never found a single one, but easily picked out at least one in each of the pictures in the article in just a few seconds. Thinking this might be a breakthrough I went and snapped a few pictures of clover patches, but alas can't spot any. I suspect I'm getting subconscious hints from the author's framing of the photos.

A case of Solomon Shereshevsky [1] is very relevant here.

[1] https://en.wikipedia.org/wiki/Solomon_Shereshevsky

He had synesthesia that made him unable to forget things for most of the life. His memory was so good he was able to recite ten and more (10+) years old dialogues word-for-word, some of those included remembering and reciting long arbitrary numbers. How so? Because almost everything he saw, heard or read was fascinating in its' own unique way.

(Shereshevsky had to learn how to forget things at later years of his life, successfully)

I do not have synesthesia, yet I've found that if I have any sort of strong feeling - direct, or through association, - about any subject, I remember everything about that subject better. Also, these strong feelings allow me to find analogues relatively easier, enriching my reasoning.

Richard Feynman described something like this in his autobiographies: when mathematicians told him to imagine two spheres, he imagined one as orange and the other one as hairy (or something like that). This way he was able to discover non-constructiveness of proofs, as non-constructive proofs have less use in physics.

So, in my experience, one can use (or learn to use) rich feelings about many things to make memory better and to find better solutions to problems faster.

I don't think synesthesia is necessarily a good explanation.

I am quite good at spotting 4-leaf clovers, but I don't have synesthesia. My eye just "catches" on them. I'm pretty sure it's actually the angle of the leaves that I'm spotting, because almost all of the false positives are situations where leaflets are at a 90° angle to each other.

(But I've found 5, 6, and 7 leaf as well.)

>> I have several hundred [four leaf clovers]. I even have a few five-leaf clovers and a couple of sixers!

That doesn't fit the ratios in my experience.. I find about 1 five-leaf for every 5 four-leafers. They should have nearly 100 five leafers, not merely "a few".

EDIT: I checked and indeed the standard ratio is 4.8 four leaf clovers per five-leaf. https://biology.stackexchange.com/questions/73279/distributi...

    10000 three-leaf
    15 four-leaf
    7 five-leaf
    4 six-leaf
    2 seven-leaf

Oh man, my grandmother was like this with finding four leaf clovers. She would just find them constantly, all the time, on command, or maybe while standing around having a conversation. Her description of it was "it's like they're just jumping up and waving at me" which somewhat fits with the author's description of motion. Never heard of anyone else like this though, neat to see others in the comments.

People claiming that weird unfalsifiable (or often unmeaningful) inner states give them magical powers has got to stop being respected.

Thinking 4 is red doesn't mean that you don't have to count anymore. It's as stupid of a claim as claiming that "hearing colors" allows people to see in the dark.

I'm a very, very fast minesweeper ( https://en.wikipedia.org/wiki/Minesweeper_(video_game) ) player, and I play in a non-marking style (meaning I just click where mines aren't rather than bothering to mark where mines are.) I realized one day that I subjectively see the spots that I know don't have mines as differently colored than the ones that I know do. That does not mean that I am not doing the calculations in my head, it just means that they are so reflexive that I don't notice them. Because I am trying to clear as fast as I can, I've seen every pattern thousands of times, and my feedback is visual, there's a ghostly sort of visual marking showing the outcome of my calculation.

This is similar to how people echolocate and have no idea that they're echolocating: "How Well Do We Know Our Own Conscious Experience? The Case of Human Echolocation" https://faculty.ucr.edu/~eschwitz/SchwitzAbs/Echo.htm

We are not necessarily aware of what we are applying complex logic to, even when it requires delicate timing and swings wildly over tiny differences. I'd go even further and say that we are necessarily less aware of calculations that we are making quickly, because being quick does not allow time for reflection.

You've just gotten good at finding 4-leaf clovers because you spend an enormous amount of time looking for 4-leaf clovers.