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My ten year old son was reading car number plates that were too fast, too far away and at the wrong angle for any of us to read or even believe that it was possible for him to read. We thought he was lying as he reeled off the whole number plate and not just some. My husband went across the road to prove him wrong and get him to admit he was making it up but he wasn't. We even asked people in the restaurant and waiting staff for their opinion and everyone was blown away. I'm totally astonished and slightly freaked out by his sight and I'm hoping someone can explain for me.

Specifics

  • I believe it was approx 20-25 metres away and I am under guessing.
  • He had only 1 or 2 seconds as the cars drove left to right.
  • Cars would be travelling 30/40 kmph along that road.
  • We were sitting in the restaurant at night time so not in a car ourselves
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    $\begingroup$ Why is this off-topic or unclear? Please comment and we can work on the question. Aging is a hot topic in Bio. $\endgroup$ – AliceD Feb 18 '15 at 13:24
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    $\begingroup$ You should provide additional details about approximate distance and speed of your car relative to other cars and size of the letters. Otherwise it would be difficult of anyone to ascertain if that was really an above-average perception. $\endgroup$ – WYSIWYG Feb 18 '15 at 13:31
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    $\begingroup$ He could perhaps be far-sighted. How does he do with close-vision tasks like reading? $\endgroup$ – jamesqf Feb 18 '15 at 19:09
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    $\begingroup$ @jamesqf he is not as fluent with his reading as his 8 yr old sister although he can read and doesn't have trouble with pronunciation. I put it down to a girl/boy development thing....I have just booked an eye test because everyone's valuable comments are making me think about all possibilities.... $\endgroup$ – Claire Feb 19 '15 at 1:45
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    $\begingroup$ @hello_there_andy just briefly read symptoms for aspergers and there is not one symptom that I could say is possibly apparent. He's advanced beyond his years socially and has been from an early age, motor skills- fine, rides quads and bikes and horses from a young age...above average academically and extension in lots of subjects too. The only thing with social or behavioural interaction is his frustration at others and often not handling situations calmly enough? $\endgroup$ – Claire Feb 19 '15 at 2:01
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The "normal" visual acuity in the Anglosphere is the 20/20 vision which means that on a Snellen chart characters with 8,86 mm height can be read conveniently from a distance of approximately 6 m.

Now there are many known people who have very sharp eyes, having the doubled acuity of 20/10. This means they can discern characters of only 4,43 mm height from 6m.

The normal car signs in the EU (and I think it is not very different in size in other countries) is 75 mm. So a very good observer can discern number plates from a distance of (75 mm / 4.46 mm) * 6 m = 100 meter or 109 yards, a normal observer from half the distance (50 m or 54 yards).

People are mostly not aware how their sight is deteriorating. Chris already said that the acuity goes down with age, but the other problem is that the lens is less flexible with age and therefore not able to focus a fast approaching car. Your son has no problem with that.

Sorry, I don't think your son is superhuman.

FOR THE CURIOUS: A rule of thumb is that normal sight has an acuity of 1 arcminute ('), the 60th part of a degree angle. This is a ratio of 0.000291 or 3 cm per 100 m (1 inch per 1 yard). A character to read consists of parts, let's look for example at E. E has five vertical sections and if you think about it, all other characters can be displayed if you have five sections available. So Snellen set the height of the characters to 5 arcminutes and the stroke width to one arcminute. The patient looks from 20 ft (= 6.096 m) away. So the height of the characters must be (5*0.000291)*6.096 = 8.866 mm

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  • $\begingroup$ That's helpful seeing the distances thank you. I believe the distance was approx 20-25 metres away. $\endgroup$ – Claire Feb 18 '15 at 21:12
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Short answer

Visual acuity decreases with age. Your son's age is within the age range that visual acuities are best. Acuity starts to decrease from about age 45.

Background

Visual acuity (visual resolution) first increases from birth up until around 4-6 years. Note that in the following graph better acuities are represented by lower numbers (logMAR scale):

acuity increase
Source: Pan et al, 2009

Visual acuity starts to decrease after 45 years. The acuity of a 6-year old is about 1 on the scale in the next figure, showing the decline in acuity in older folks. Note that the graph starts at 30 years and acuities are already less than that in the former study's end point (look at the lower set of lines, i.e., the uncorrected ones). Also note that better acuities are higher up in the scale as this graph expresses acuities in decimal Snellen equivalents

old age
Source: Gittings & Lozard, 1986

Hence, very likely, your 10-year old's vision is not superhuman (sorry!), it's just a lot better than yours. However, if you are younger than 45, we might conclude your acuity should be comparable and your son may be a visual rock-star - statistical outliers do exist and a simple visit to the optometrist will tell you! However, if you are near-sighted and are not using corrective vision aids (glasses or the likes) then this may be the cause of your lesser visual acuity.

References
Pan et al., Optom Vis Sci 2009;86:607–12
Gittings & Lozard, exp gerontol 1986;21:423-33

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    $\begingroup$ Thank you. Yes I am 40 which is why we asked others in the restaurant and one guy was 18 and he laughed but I hadn't thought that he perhaps had terrible vision for his age! My 8 yr old daughter also couldn't decipher even one letter either so may be more important to check hers! It was approx 25 metres away, was dark and there was prob 1 or 2 seconds for him to capture it as it drove left to right and at a speed of 30/40kmph $\endgroup$ – Claire Feb 18 '15 at 21:16
  • $\begingroup$ @AliceD, Why did you protect this thread for? It's only 2700 views. $\endgroup$ – Pacerier Sep 29 '15 at 12:15
  • $\begingroup$ @Pacerier - not so much because of #views, but it has received multiple good quality answers and it was drawing in low-quality answers (since deleted and hidden from your view). $\endgroup$ – AliceD Sep 29 '15 at 12:18
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He may have extreme acuity, or he may even have an extra cone type that allows him to see extra colors (and more color attunement may allow easier reading of those particular plates). But, you won't know anything for sure by asking on here. Take him to an ophthalmologist and let us know what the doc says! If you aren't 40+ and have 20/20 vision and he's seeing things better than you, then yeah, he probably is special!

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  • $\begingroup$ Thank you for your reply! My daughter is 8 and she could just see a blur and the 18 guy sitting next to us just laughed and said no chance he could see either but yes as per other responses above, I hadn't thought that everyone else compared may have particularly poor eye sight! I think I shall pop to have his eyes tested and will post on here the results $\endgroup$ – Claire Feb 18 '15 at 20:57
  • $\begingroup$ @Claire you should get in the habit of upvoting answers that have helped, some of us crave unicorn points $\endgroup$ – hello_there_andy Feb 19 '15 at 2:05
  • $\begingroup$ @hello_there_andy......how do I do that apart from singing praises in comment box!? $\endgroup$ – Claire Feb 19 '15 at 3:23
  • $\begingroup$ @Claire Just click the up arrow at the top left of the answer - but you need to collect some amount of points yourself first - so maybe it does not work yet - there would be a message explaining it when you try. You have 36 points "rep" ("reputation") currently. Three upvotes on your question would get you to 51, for example. $\endgroup$ – Volker Siegel Feb 19 '15 at 7:16
  • $\begingroup$ A functional male tetrachromat has yet to be found. Finding one might count as "superhuman" vision, as much as any trait possessed by a human could be called such. $\endgroup$ – Dan Hook Feb 19 '15 at 18:45

protected by AliceD Feb 24 '15 at 12:48

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