When I began trading crypto somewhat seriously in the past year I gradually stepped up my safeguards. I bought, sold, mined, and traded (through Shapeshift) and although I sometimes spent some agonizing time waiting for confirmations, most transactions did what they are supposed to do - come through.

To err is human, however. In my professional life I've learned that there is always a certain amount of error in human-entered data - in fact, various sources quote an inescapable 5% minimum error rate. One in twenty data entries, also your own, contain an error. A typo. The right data, but in the wrong place. The wrong address.

It has happened to me twice now that I've sent some amount of cryptocurrency to the wrong address. 2 in 66 transactions according to my CoinTracking records, that's about 3%. Not bad! They were pretty stupid, though.

The first time a bitcoin transfer to Shapeshift was cancelled because I had sent a larger amount than the upper limit. Filling out the remuneration form I entered a bitcoin address that was... the address of an exchange I had bought bitcoins, not a returning address of my own. I must have messed up copying and pasting addresses and kept the wrong one on the clipboard. Somehow I kept my cool and sent a few emails to both other parties. It took a few days - everyone responded very helpfully and professionally and soon enough I had my bitcoins back.

The second time I mined ETC for a week on my home mining rig, to see how well it compared to mining ETH or XMR. The address representing my worker was an ETC address generated by Parity - or so I thought. What I pasted from the clipboard was a Metamask address that I had set up to buy CryptoKitties for my son to play with. (We sure had some brief fun with those crypto-felines before their value dropped.) Great, the address now holds the ETC I mined and what was left of the ETH used for buying a few kitties. As gastracker.io is happy to tell me, "Address has money on both ETH & ETC chains". Yay. The downside is that Metamask does not support the ETC Network. Nice - the next thing to do is to find a way to transfer the ETC off Metamask. I've tried this route but this is a discontinued effort. Anybody got a hint?

Yes: users are fully responsible for entering the correct address. Any error could result in an unrecoverable loss. I blame my 3% cognitive slips entirely to myself. To my mind.

How to, then, nudge the mind so that it does not trip? One idea would be a browser extension that pops up when you paste a crypto address in a web page, saying things like 'you are now entering what looks like an ETH address' - if anything, it may give you a cognitive nudge that is just large enough to make you doublecheck yourself.

That's what those 'Are you sure?' dialogues are for, after all.