In his recent excellent blog post, Yvain discusses a few "universal" (commonplace) human experiences that many people never notice they don't have, such as the ability to smell, see some colors, see mental pictures, and feel emotions.  I was reminded of a longstanding argument I had with a friend.  She always insisted that she would rather be blind than deaf.  I could not understand how that was possible, since the visual world is so much richer and more interesting.  We later found out that I can see an order of magnitude more colors than she can, but have subpar ability to distinguish tones.  And I thought she was just being a contrarian for its own sake.  I thought the experience of that many colors was universal, and had rarely seen evidence that challenged that belief.  

More seriously, a good friend of mine did not realize he suffered from a serious genetic disorder that caused him extreme body pain and terrible headaches whenever he became tired or dehydrated for the first three decades of his life.  He thought everyone felt that way, but considered it whiny to talk about it.  He almost never mentioned it, and never realized what it was, until <bragging> I noticed how tense his expressions became when he got tired, asked him about it, then put it together with some other unusual physical experiences I knew he had </bragging>

This got me thinking about when it is likely we might be having unusual sensory experiences and not realize for long periods of time.  I am calling these "secretly secret experiences."  Here are the factors that might increase the likelihood of having a secretly secret experience. 

1) When they are rarely consciously mentally examined: experiences such as the ability to distinguish subtle differences in shades of color are tested occasionally (when choosing paint or ripe fruit), but few people besides interior decorators think about how good their shade-distinguishing skills are.  Others include that feeling of being in different moods or mental states, breathing, sensing commonly-sensed things (the look of roads or the sound of voices, etc.)  Most of the examples from the blog post fall under this category.  People might not notice that they over- or under-experience or differently experience such feelings, relative to others.  

2) When they are rarely discussed in everyday life: If my experience of pooping feels very different from other peoples' I may never know, because I don't discuss the experience in detail with anyone.  If people talked about their experiences, I would probably notice if mine didn't match up, but that's unlikely to happen.  The same might apply for other experiences that are taboo to discuss, such as masturbation, sex (in some cultures), anything considered gross or unhygienic, or socially awkward experiences (in some cultures).

3) When there is social pressure to experience something a certain way: it may be socially dangerous to admit you don't find members of the opposite sex attractive, or you didn't enjoy The Godfather or whatever.  Depending on your sensitivity to social pressure (see 4) and the strength of the pressure, this could lead to unawareness about true rare preferences.  

4) Sensitivity to external influences:  Some people pick up on social cues more easily than others.  Some notice social norms more readily, and some seem more or less willing to violate some norms (partly because of how well they perceive them, plus some other factors). I can imagine that a deeply autistic person might be influenced far less by mainstream descriptions of different experiences.  Exceptionally socially attuned people might (perhaps) take social influences to heart and be less able to distinguish their own from those they know about.  

5) When skills are redundant or you have good substitutes:  For example, if we live in a world with only fish and mammals, and all mammals are brown and warm and all fish are cold and silver, you might never notice that you can't feel temperature because you are still a perfectly good mammal and fish distinguisher.  In the real world, it's harder to find clear examples, but I can think of substitutes for color-sightedness such as shade and textural cues that increase the likelihood of a color-blind person not realizing zir blindness.  Similarly, empathy and social adeptness may increase someone's ability both to mask that ze is having a different experience than others, and the likelihood that ze will believe all others are good at hiding a different experience than the one they portray openly.

What else can people think of?

Special thanks to JT for his feedback and for letting me share his story.

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The huge problem is that we lack vocabulary to talk about unique qualia. Our words come from talking to other people and if nobody around us has the same qualia as we are, nobody gave us a word.

At the moment I'm learning to distinguish colors better via an Anki deck. I use the CSS color name definition. Seeing the difference between navy and midnightblue is still hard for me but I'm confident that I can learn it with practice. Some day I will hopefully even be able to tell apart snow from floralwhite.

I like the particular deck and if someone wants to train their color perception I'm happy to share it. It's build in a way that you get progressively more difficult decisions and provides years of fun at 5 new cards per day.

I would also like to create a deck to train sound perception. Does anyone know of a good tool that can automatically produce sound files with a specific pitch for pitch training? At best a tool that can be used via the command line.

Regarding color you might want to have a look at the as usual funny and detailed XKCD color survey:
Even better than that is this series of blog posts, which talks about color identification across languages, the way that color-space is in a sense "optimally" divided by basic color words, and how children develop a sense for naming colors:
How well calibrated is your monitor? My wife recently had a "That's not what I wanted!" experience after discovering that the brightness levels which are optimal for watching movies are not optimal for designing artwork which looks the same after printing. Unless you've done some careful tweaking you might not be learning the colors you think you're learning. For sound generation, what operating system are you using? Alsa (at least on Ubuntu 13.10) comes with "speaker-test", a command line program which can be used to play specified frequency sine waves, and alsa itself can be configured to allow you to save sound output to files.
..And that's pretty much the story of how at work we ended up with a hideous orange conference table instead of the nice warm brown our department chair envisioned
Calibration is something I don't learn, at the moment I can more about fine color distinction. I use windows, but I might write a script and run it on a linux computer to get files, I will think about it.
You're teaching yourself to associate labels (e.g. "midnight blue") with particular colors. You seem to be doing the colors on your monitor and I doubt your monitor is color-calibrated. This implies that you're looking at a somewhat-randomized version of a true color. Your monitor also has a limited gamut (the set of colors that it can display) and for some monitors the gamut is very limited to the extent that they have to simulate some colors by dithering. Most uncalibrated monitors are too bright and too blue. Basically, display of proper colors on a screen is complicated and you must take active steps (e.g. color calibration) to make it happen.
Actually the css label is "midnightblue" without a space. For my purposes I don't think it's a problem to treat the word true as meaning whatever the hardware interprets it too mean. I want to get better at precision of color distinction. Having accurate labels is secondary.
Your sentence doesn't make sense, but keep in mind that we're talking about what your local, particular, individual hardware interprets it to mean. My hardware (my screen) will likely interpret it differently. Screens of random people will interpret it differently again. Also a lot of LCD screens use what's known at TN (twisted nematic) panels and the great majority of them are 6-bit panels, that is, they drive pixels at only 2^6 = 64 levels. So, for example, they can only show you 63 levels of blue (0 is off/black) even though the standard software treatment of color is 8 bits per primary for 256 levels. The TN screens mitigate this problem through dithering. Human vision is highly adaptive to ambient light, in particular its color temperature. We perceive colors differently in the sunlight, in the shade, or under a tungsten lamp. And these are full-spectrum light sources. Fluorescent lights are not, they have spikes and voids in their spectrum and that affects certain colors under them as well. As I said, it's complicated.
Yes, there should have been the word "problem" when I wrote the word "probably". I know that human vision is complicated. I however also know my bit about measurement theory. The important thing isn't that a measurement is "true" but that that it has features like sensitivity and specificity. Accuracy and precision are other words to speak about measurements. When dealing with a complex subject the important thing is whether your map of reality is good enough for the purpose for which you want to use it. I think the way my computer models colors is good enough to produce a valid training effect that helps me to get better at distinguishing colors. I could create a randomly generated filtered deck out of 100 mature Anki color cards and test it at the computer of someone else and see whether the particularities of my specific computer monitor produce a problem. It's a question that has an empiric answer and in a year when I have put more training into the colors I probably will do something like that. At the moment I have one day 70% correct cards and the next day 85% right cards, so it's not stable enough for good test. My notebook has a slightly different color profile than my 24" monitor. Switching between the two doesn't produce issues I can perceive. It doesn't feel like everything is suddenly wrong. My brain seems to be able to make the necessary adjustments that I can still answer the cards correctly.
What do you mean by that? Let's use meatspace examples. Do you want to be able to look at a wall and say "this is color X"? Do you want to to be able to look at two walls side by side and say "These are different colors"? Do you want to be able look at a wall, look at another wall the next day and say "This is the same color as I saw yesterday"?
Being able to answer the question: What color is this isn't very useful. It's not what separates the person who rather wants to be deaf from the person who rather wants to be deaf. I want is a cure for my partial blindness. I want to perceive more bits of information through the visual channel. I don't care for 'is' or 'true'. I'm post- aristotelean. To quote the constructivist Heinz von Foerster: Truth is the invention of a liar. Just in case you think, I'm off-topic, I'm not. Those Anki cards are a result of among other things reading Korzybski's Science and Sanity. To go back to questions I want to be able to notice if a website I visit changes their color scheme in a way that exchanges navy with midnightblue just as I'm now able to notice a change from red to green.
Ah. Well, this is useful to know. Given that your brain's processing bandwidth is severely limited I think it's mostly an issue of controlling your attention but experimenting is good.
I don't think there a good reason to believe that. I think quite often the limiting factor is time spent in deliberate practice and not lack of neurons or similar hardware problems.
Sounds like you want sox. To make an mp3 that plays an A 440 for 1 second you would do: sox -n a440.mp3 synth 1 sin 440 But note that most real world sounds are a combination of many frequencies, so training on sine waves may not be what you want.
I would think that training on them provides useful skills that generalize more broadly. It's probably not perfect but it's easy to create cards with binary choices that can get progressively more difficult. The goal is getting to a point where I engage into deliberate practice of distinguishing sounds and using Spaced Repetition to do it. If anyone who's good at sounds has better ideas about creating a Anki deck to train distinguishing sounds, I would be happy to hear ideas. I also try to train phonemes, but creating good cards for it proved to be hard. The first cards I created where simply to hard for myself as I'm not good at audio perception. I can hear a lot more in a Salsa song than I could hear 5 years ago. I think that it's worthwhile to invest significant time in getting to perceive more bits of reality in daily life. I'm still at the phase of experimenting about how to train myself and others to have richer qualia, but I think it's an area worthy of further investigation. Pitch seems to me like a very straightforward concept, but I'm also willing to learn other ways of distinguishing sounds.
Instead of phonemes in isolation, it should work to train on them in words as minimal pairs. For example, to train the difference between /b/ and /d/ you would test discrimination between /bog/ and /dog/, /cab/ and /cad/, /cabby/ and /caddy/, etc.
Under different light contexts an reflective object might be closer to either midnight blue or navy. Have you attempted using paint chips or something to test yourself under sunlight versus florescent light or anything? Also, for sound perception: sox(1)
I know at the moment it seems to me that the colors are far enough apart that light conditions at my PC are not the main problem. My notebook is slightly differently configured and I didn't judge many Anki cards wrongly when answering on the notebook instead of my main monitor.
Most things don't produce their own color though, they reflect varying amounts of the incoming spectrum. If that incoming spectrum is different, the outgoing spectrum is different. You can take advantage of that in various ways, but it might also confound the question of what color "is" this object. Or maybe you automatically take that into account by using the ambient light as a reference, I was wondering whether you had tested for that or not?
At the moment I haven't tested. I spent a total of 7 hours with the average of 5 minutes per day on the Anki cards and I seem to be getter better at color distinction. Every card provides a binary choice. I have cards that present me with two color words and a large circle that's filled with the corresponding color. The difference of the colors is at the beginning stage where I'm still at least a total 32 different hex values. I also have cards that ask for the hex value of the colors. There were some days were I traveled and used my laptop in other light conditions. They weren't a problem. For the time in 7 years I created cards to distinguish 4dc636 from 4dc637. That might run into issues with light conditions. I don't know whether it does and whether the human mind is trainable to distinguish colors as finely, but I will find out if I continue spending my 5 minutes every day. I don't like "is" anyway for the reasons Korzybski layd out. I want to increase the amount of bits I perceive through the visual channel. It's an open experiment. The outcome might be that I have color distinction in a few years that allows me to impress people with stunts. I might learn something valuable about colors that can be made into scientific paper or blog post. I also expect that I will get better at usability design even if I don't get superhuman color perception abilities out of the project. But you are right that having data about the light conditions would be good. I opened a thread on the QS forum about the search for a proper tool.

From time to time I hear about people going to their physician when they realise something is off about their body accidentally when someone mentions something that makes them realise they are unusual in some respect. I am then often surprised that these people report the physician saying something along the lines of the phenomenon being well documented and benign.

Personally, I have a couple of tones in my ears for the first two decades of my life without realising that tinnitus is unusual and I do not know what absolute silence is. Ironically, I also have exceptionally great sensitivity to quiet sounds. And, again ironically, I have trouble understanding human speech when there is background noise.

I was surprised when I first moved in with roommates to see how one of them and some of the neighbours were just absolutely noisy. After some inquiry I realised that they are just not as bothered by noise as I am. Oh and apparently they are unable to hear as sensitively as I do.

Further, I hate background music above a certain, quite low, threshhold if I want to maintain a conversation. Other people's conversations are similarly challenging. These facts do explain quite nicely why so many people like clubs, bars or pubs but I do not.

There are plenty of these little things and it maddens me every time I see psychological studies or policy assuming homogenity in the human population. We are different in so many often quantifiable ways. I am not sure yet of the practical use of these little facts but I am sure there is.

Now that I have read all the comments on the linked blog post I have some thoughts to share that I want to have judged seperately. This seems like it would be easy to test. What is the relevant literature to design a suitable experiment for this? Similar to the other case, I would like to test for a correlation between enjoyment of music and this. I am not sure what the practical use of this data is but I am interested in it anyway. Reading these I wonder about how these discrepancies arise. Are they usually genetic in nature as in that some genetic factor determines certain neurological structures or are they the result of some environmental factor too? The jasmin example sounds more like a defective connection between the brain and receptors in the nose. Then again, only some part of the population is able to smell some metabolic product of asparagus in urine and we know this is a single gene mutation. The faceblind example sounds like some environmental factor being absent such as plenty of faces. The art experience thing I don't know. Do high IQ people have more of these unusual structures? In my experience more intelligent people report such strange stuff more often and/or are able to empathise with me more. Then again, it could be that intelligent people in general are just more aware of these things and such more considerate. Anyway I am very happy to see that other people have plenty of these little stuffs and I am not alone in this. I am very happy to be able to participate in this community.
Perhaps high IQ people are better at describing them?
Jasmine, especially the bulbs have a strange, sickly unpleasant smell for me (similar to some of the smells in old toilet rooms, maybe - not the urine part, more like a mushy, fungus smell). I could never find any mention of other people having the same perception.
Me too! I learned that there's a gene related to oxytocin receptors, Rs53576, that affects auditory processing. Those with G;G are optimistic and empathetic, handle stress well, and are good at understanding speech in noisy environments, while the other genotypes don't possess those qualities. (Please note that this information comes from only a few studies, and should be taken with skepticism for publication bias and other errors. And of course even if it's correct, there could be plenty of other reasons to have difficulty understanding speech in background noise other than this particular gene.)
This lends some credence to the hypothesis that quite some part of the variation in population is due to genetic mutation.
Huh. I'd describe myself as optimistic, empathetic, and handling stress well, but I am terrible at understanding speech in noisy environment.s

The presence of an object (or even my own finger) near the center of my forehead causes a tingling sensation, which can even shift directions (but still, always centered on my forehead) as the object moves.

Does it happen if you do not know that it is there?
Yes. (Edited: will re-test.)
Same, well, in my case, right above the nose, between the eyes would be the epicenter (so around the parietal eye?). I have no good explanation for it either. When I was a child I assumed it might be a magnetic sense, though that wouldn't fit well with any random (non magnetic) material triggering it. I observed too that it tends to get stronger and the zone where it triggers gets larger over time if I keep the stimulus going, to eventually plateau after maybe around 10s. It especially gets stronger if I concentrate on it, and if I gently move the object around, and may not trigger sometimes, if I am not paying attention to it. Another hypothesis was that it's muscles tensing (like a frown) because you're bringing something in range of a dangerous zone (between the eyes. For some reason it often made me think about how you kill octopi, with a stab between the eyes). But this doesn't appear to be triggered in other similarly dangerous zones.
It doesn't have to be a primary physical sensation coming from your nerves for you to experience it. Note that you are always aware of the things near your face causing this sensation via other senses or intentions. Also, humans don't have a specialized parietal eye and the pineal gland in a primate is buried deep within the brain by the growth of the cerebral hemispheres up and around it. If anything it's slightly to the back. Still probably has photoreceptors but they are not capable of any directionality and any light that got there would need to pass through several inches of scalp and skull and brain. I'd believe that the half a dozen or so cryptic rhodopsins recently discovered expressed throughout muscle tissue had something to do with response to light in a human sooner than that.
Oh my god I thought I was the only person. It goes away if they make contact. Is it static electricity?
It happens with all kinds of material, so I don't suspect it's electrical. My hypothesis is that the photosensitive cells in my pineal gland are playing games with me.
That thing's dead center in the middle of your head, no particular spot would be terribly much more sensitive (other than shooting bright light in through your ears).
I have the same, though it seems to be stronger when the finger is right in front of my nose. It always stops if the finger touches me.

I suspect I'm a supertaster. I'm extremely sensitive to bitter flavors, to the point where I can't eat olives or drink beer or coffee. It's torture for me. My father always complained that I put too much sugar into the coffee I made for him, but whenever I tested it I couldn't imagine how anyone was able to stand it without at least four spoonfuls. Every single person I know will swear to me that bell peppers are sweet, but in my mouth they taste a murderous bitter. Celery is out of the question for the same reason.

I am sure this can be tested by 23andme.
It is, yes. Doesn't seem to be the whole story, though -- according to my 23andMe data I have two dominant alleles at that site, but I don't find bitter flavors particularly aversive.
I don't know how high or low 23andme's error rate is but it has to be taken into account. And of course, as always with genetics, environmental factors play a role.
And a couple thousand other genes with many many many variants apiece that affect some part of your nervous system from your tongue to your brain, or a variant of the gene that 23andme sees as a known variant from part of its sequence that the microarray binds to but has a rare or unique difference elsewhere in the same gene that isn't in the catalog.

Both my eyes may from time to time perceive colors in a different way. When they do, one would see everything in more greenish-blue hues, the other in more red-yellowish hues. It's often the case when I closed one eye for a moment, or when that eye was on the pillow side after resting. So I assume it's either temperature-related, or simply that one of my eyes' cone cells were too exposed to, say, red, because of red light filtering through my closed eyelid, and therefore were less sensitive to it afterwards.

(I scored 3 on

I have observed different color temperatures in my left or right eyes some times and observed that these can be changed after wearing red/blue glasses; by swapping which lens covered which eye, I could correct them both back to a more balanced condition.
I have this too. Also occasionally when I am reading a dead-tree book in the sunlight, in one eye the text will appear red or green instead of black.
I have this too.

I think I have qualia associated with small numbers.

The closest analogy I can think of is "butterflies in your stomach, but with a pitch". I say pitch not because it's auditory (it's not), but because it seems to be the same feeling but higher or lower for different numbers (not in intensity, but in ... pitch).

I associate genders with digits, based on their shapes. 1, 4, 5, and 7 are distinctly male. 0, 2, 6, 8, and 9 are distinctly female.
Is it possible that this has something to do with how rounded the shapes are? I noticed that the ratio of cusps to rounded edges (a circle counting for two) is 1:0, 2:0, 3:1, 2:0 for the male digits and 0:2, 1:1, 0:3, 0:4, 0:3 for the female digits. Though obviously this can change with typeface it often remains more or less true.
Yes, I think that's where the association comes from.
Thank you. People with number form synesthesia sometimes have the first twelve digits in the form of of a clock face, I was wondering if something similar was going on with male bodies usually being relatively angular in comparison to female bodies.
I doubt it. For me, 1, 3, 8, and 9, are all male, whereas 0, 2, 4, 5, 6, and 7 are all female.
3? 15? 26? 52? -1?
I associate genders with digits, not numbers - so 15 is 1 and 5, 26 is 2 and 6, and so on. 3 is female.
Neat; thanks!
These experiences sound like synesthesia, in case anyone's unfamiliar with the concept and wants further reading.
This reminds me of people that say that (small) numbers are not on a straight, equidistant line for them but on some kind of curve where numbers do bunch together or take turns.

I think that I lack a precise sense of relative pitch over time - as in I can only easily compare tones that are simultaneous or directly one after the other. Give me three tones where pitch first, say, raises and then lowers again, unless they are either identical or a good octave apart I have a hard time telling if the first or third is higher in pitch.

There is a word for the opposite of that (perfect relative pitch), so you're probably in the majority here.
Not so sure about that... here, example: I can't tell if the first or third chime is higher pitched. I can tell it goes up and down but even separated by two seconds I can't leap over the middle one. At least compared to several of my friends from college onwards, this seems unusual.
If you can, try testing your ability to determine whether the chimes are being played in the normal order or backwards.
No. I don't have perfect pitch, but I can perfectly well tell apart... Hm. Looking at Wikipedia, maybe I do have perfect pitch. Huh. This bears looking into.
There are a couple varieties of perfect pitch; "true" perfect pitch (perfect absolute pitch) is rare, but perfect relative pitch, which is being able to recognize precise intervals, is fairly common among musical people. IIRC, my intro music theory class at a not-musically-distinguished liberal arts college had the professor and ~5 students in a class of 40 who had perfect relative pitch.
Seems I have perfect relative pitch. I never knew!

I have a friend who was surprised to discover the concept of a "lucid dream". It turns out all of his dreams are lucid and he assumed it's the same for all people.

A psychological experience I have (albeit very rarely). I suddenly realize that I am really me. In comparison, all the rest of life feels like watching a movie in which I am just one of the characters. Sorry if it came out confusing, it's a bit hard to explain! With age the occurrence seem to have become even rarer (I don't remember when I had the last one but it might have been over 10 years ago).


When I am in familiar surroundings, I feel like I can very easily go to the next room or out of the building at all, and it's a bit like I have already gone there. I don't mean any kind of 'out of body experience', just that there's some fuzziness in my mind about where exactly I am. In contrast, when I got stuck in an airport halfway across North America, with some uncertainty as to whether I would reach my destination the next day or the day after that, I felt very clearly that I was exactly bound by my body. The world began, sharply, just outside my eyes. Has anybody felt the same?

Ability to distinguish taste varies quite a bit, with some people only really tasting strong flavors.

I can distinguish patterns in higher tones in music better than low tones. All drum and bass music sounds indistinguishable to me.

Vocal patterns have a bigger influence on interpersonal communication than generally assumed. Interruption vs waiting, deeper vs higher tone voices, pace, non-word vocalization, physical expressiveness (hands, face, body) etc. Some people find certain patterns attractive/aversive and this influences how seriously you take the speaker.

I have two such perceptions which may or may not be related.

Since I am very young every now and then I have had an temporary alternation of vision. Suddenly everything looks much farther away than it is and as if I'm looking through a tunnel with dark and/or blurry sides. When I was young, maybe 12 years old and told my parents this the thought I were tired. But I wasn't. It happens during the day. It is distracting but it goes away after closing the eyes for some time and resting. Or whatever. Doesn't stay longer than an hour.

The other thing is a highte... (read more)

I AM NOT A DOCTOR AND MY OPINION IS QUESTIONABLE. But your visual symptoms suggest something like this:
Duely noted. Thanks for the links. That about fits it. I remember seeing that hit but the name implied something too much out of proportion. I guess that I have had very mild cases of Alice in Wonderland syndrome. Seldom. No migraine. No other effects. The touch effects may have the same source but occurred independently. This is just a generic term containing Alice in Wonderland syndrome. This doesn't fit it because I didn't see less. It was just like looking at the same scene but distorted. Somewhat like the effect of the telestereoscope I guess .

Human genetic diversity is huge and still increasing quickly:

I bet half of the 'deleterious' mutations mentioned in the article relate to more or less unusual experiences.

Still ongoing? Of course. Huge? Not at all. We had a population bottleneck a few thousands of years ago, and our diversity suffered as a consequence. An extended family of chimpanzees displays more genetic variation than the entire human species:

Interesting. That puts it into perspective. ADDED: Thinking about it some more I wonder what that means. Whats huge in human diversity is not the total diversity (at least as compared to chimpanzees) but the amount of increase in diversity over time. It would appear that selection pressure is lower on humans than on champanzees at least in the last centuries.
It's interesting to think about what society might have been like, if it wasn't. You'd expect a lot more variation in intelligence along with everything else. Potential novel fodder.
Please someone write it. I love alternate history.