Revelations that millions of Australian $50 notes were printed in 2018 with a typo made people wonder how it could have gone unnoticed by so many eyes, for so long.
The Reserve Bank of Australia in May confirmed the word "responsibility" was misspelt on hundreds of millions of notes before they entered circulation, including a batch of about 46 million new notes printed last year.
The word "responsibility" is misspelt as "responsibilty" three times in an excerpt from Edith Cowan's maiden speech to the West Australian parliament in 1921.
But as soon as it’s realised just how 'micro’ these prints are, the focus of curiosity shifts to how it was possible for anyone to discover the typo at all.
Pictured is a current circulation $50 note printed with the word "responsibility" spelt incorrectly in Sydney, Thursday, May 9, 2019. Source: AAP
Microtext on banknotes is an anti-counterfeiting measure adopted by some countries where texts are printed in a size and font requiring magnification to read with the naked eye. Without magnification, the text may appear as a line.
SBS Korean spoke to Associate Professor Andrew Anderson in Melbourne University’s Department of Optometry and Vision Sciences about things related to microtext. The following are direct exerts from the interview.
Q. How much smaller is the microtext printed on the new $50 notes compared with the smallest writing on a vision chart?
A. So I got out my ruler to check what sort of would the size be and it seems like the microtext, there is little bit of variation depending on which part of the banknote you’re looking at, but it seems to be roughly the letters are around about 0.3 or a third of a millimetre high so it’s quite small. How that relates to a vision chart, there is no simple answer to that because a vision chart is often a far distance away and it’s sort of a fixed distance away from the person whereas your banknote you can hold at a variable distance away from your eye and depending on how far away you hold it from your eye will influence how big the image is of that microtext on the retina at the back of your eye, so there is no simple correspondence. However if you’d hold your banknote at about 40cm away from your eye given the text is about a third of a millimetre high, then that microtext would be about half the size of the 20/20 line on a vision chart what we would call normal healthy vision so you’d have to have really quite extraordinary vision to be able to resolve that text at 40cm.
Associate Professor Andrew Anderson. Source: SBS
Q. Microtext is used because it is supposedly "unreadable" to the unaided eye, but there are people who can read the microtext on a $50 note with little difficulty. Why is it possible for some people and what does it mean?
A. I imagine people who are doing that are younger people who are able to hold the note substantially close to their eye and that means that text appears larger simply because it’s close to the eye and forms a bigger image at the back of the eye. It’s also possible if you’ve got high-degree short-sightedness, if you take off your glasses then people who are highly short-sighted can also hold things very close to their eye and so again that microtext would then appear substantially larger to them. So I don’t think people who can resolve the text necessarily have supernormal vision. It’s probably more that they can maybe more comfortably than other people, hold the note a little bit close to their eye than other people.
Q. So it doesn’t mean that they have exceptional vision?
A. I wouldn’t have thought so. I mean of course it’d be nice to examine some of these people and see what their visual characteristics are, though amongst healthy normal people their visual acuity their ability to read a letter chart there’s some variation but it doesn’t vary a great deal. Most people have around about 20/20 vision give or take a line or two. I think the much bigger variation will be how close can someone hold one of these notes to their eye and if you are a young person your eye can change focus quite comfortably and can focus on things quite close. Whereas if you get to between your mid-40s and your mid-50s that’s when everyone will go into some sort of reading glasses and that’s because your eyes lose that ability to change its focus. So people on that sort of age bracket wouldn’t be able to bring the note close to their eye just becomes impossible and because that text is much further away from their eye that texture is gonna appear a lot smaller.
Q. Is it possible for us to train our eyes to be able to read such tiny text?
Pictured is a current circulation $50 note printed with the word "responsibility" spelt incorrectly in Sydney, Thursday, May 9, 2019. Source: AAP
A. There is probably small amounts you can do so you can become familiar at how the shape of the text appears when it’s very tiny that’s probably not going to affect things a great deal if you got one of those focusing errors then I suppose if you did exercises that might improve your ability to focus up-close so it helps you to hold the microtext close to your eye. But in general I would think most people, their ability to either read or not read the text is going to stay fairly similar despite exercises and unfortunately as you get older and you lose that ability to focus close-up it’s probably going to become harder and harder to read that microtext unless you have some sort of magnifying aid.
Q. Does reading or trying to read microtext have any potential consequences in terms of vision?
US dollar notes have 15 micro signs. Source: ICHPL Imaginechina
A. I don’t think you’d be wanting to do extended periods of reading microtext if nothing else I imagine it’d be reasonably uncomfortable to do so. There is some indication that short-sightedness is related to near work doing extended amounts of near work but we don’t fully understand exactly what are all the causative factors people going short-sighted. But I don’t think episodically trying to read the text on a banknote is gonna cause any particular harm to your eyes.
Q. How small does microtext need to get before it becomes humanly impossible to read?
A. So if we take short-sightedness out of the equation and we just look at people’s natural ability to focus close-up and they don’t have any need for glasses and we are dealing with young people, we probably need to get around about half the size again to get to the limit of 20/20 vision. But some people actually have slightly better than 20/20 vision so it’d probably need to be around about 4 times smaller to guarantee that people even when they were holding right up their eye, around 10cm away, still would be incredibly unlikely be able to read that text.
