May 28 2009

Are We All Synesthetes?

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Comments: 38

Synesthesia is a rare and interesting neurological phenomenon in which one sensory modality crosses over into another. Synesthetes therefore may see sounds, or taste colors. Abstract concepts may also evoke sensory experiences. In color-graphemic synesthesia letters or numbers evoke the perception of a specific color (for each individual the same number will always evoke the same color). In ordinal linguistic personifcation, days of the week or months of the year convey a specific personality. Other forms of synesthesia involve spacial relationships and size. Over 60 forms of synesthesia have been reported.

What is happening inside the brain in synesthetes is currently under study, but early evidence suggests that their brains are hardwired for the experience – literally there is a cross-wiring where one type of sensation or information processing leaks over into another.

A recently identified form a synesthesia is visual motion to sound synesthesia – people can hear visual motion or flickering images. While the overall prevalence of synesthesia is estimated at less than 1%, visual sound synasthesia may be more common. On a personal note, I have experienced this myself on several occasions when I was profoundly sleep deprived. Every time I blinked my eyes or scanned my eyes across different levels of lighting I would hear a distinct “whooshing” sound.

Charles Spence, a professor of experimental psychology, performs crossmodal research at Oxford University. He is looking at the effects of processing multiple sensory modalities simultaneously in the normal population – and he thinks that to a certain degree we are all synasthetes. On his website he writes:

Synaesthesia is a rare condition in which people report, for example, ‘seeing’ a colour when they hear certain words, like the days of the week, or numbers. Everyday language also uses cross-modal correspondences to describe a variety of sensory experiences – tastes can be ‘sharp’ and colours can be ‘loud’, for example. But can such synaesthetic correspondences be demonstrated in normal individuals for simple stimuli, such as brightness, size, colour, motion etc. This project investigates a number of questions in this line.

He explores things like, for instance, what name people think fits an abstract visual image. For example, which of these two shapes do you think is called “bouba” and which is called “kiki?”Most people will say the purple shape is bouba and the orange shape kiki. Why?

He argues that everyday speech is full of such multimodal associations. We might describe a bright color as “loud” or the taste of a food as “sharp.” The question is, do these associations have anything to do with synasthesia?

Even given Spence’s research findings, I am inclined to think that these are discrete phenomena and are not analogous to synesthesia. For example, what names we would give shapes and tastes may be a predilection hard-wired into our language cortex. Words do sometimes sound like what they mean. The sounds of words can sometimes convey emotion or give a clue as to what the word might mean. Is it a pleasant word or a harsh one? Such built in associations would help us understand and remember language – it gives us a feel for a language we would not otherwise have.

Yes, this involves visual information being accessible to our language cortex – which is also necessary for reading. The different parts of the brain do communicate with each other. I think, however, we should no conflate all such processing with synesthesia, otherwise the concept of synesthesia will lose its specific meaning.

I like the term multimodal processing better. It suggests a higher order processing that brings together multiple modalities of thought or sensation and combines them into a unified experience, or makes associations among them. Synesthesia, on the other hand, is more of a direct involuntary connection between primary sensory or processing modalities, causing one to actually see a color in a number, or hear a sound in response to visual stimuli.

In other words, the evidence (and everyday experience) does support the notion that we all engage in multimodal processing. Charles Spence’s research is exploring how this type of processing is used to enable us to navigate our complex sensory world. For example, he talks about putting a voice and a face together in a crowded and noisy room. Mere temporal and spacial coordination is not enough, there needs to be a multimodal connection linking the sound of a person’s voice with their image. This is a plausible hypothesis for the advantage of such multimodal processing.

But this is not the same thing as synesthesia. At least I don’t think so, but I may be wrong. Research, including that of Charles Spence, will likely shed light on this questions. Spence thinks that normal multimodal thinking is a tiny bit of synasthesia, and synesthesia is an exagerated version of this more typical processes. This may turn out to be correct, and may explain why synesthesia occurs at all. Many neurological phenomena are simply exaggerated or atypical versions of more typical hardwiring.

It is therefore a common question in neurology – is a specific neurological syndrome an entirely new type of phenomenon or is it an exaggerated version of an existing typical phenomenon? An anxiety disorder may simply represent adaptive anxiety unhinged. Or is it a pathological state – wiring that does not normally exist, or a mutation in the gene for a neurotransmitter?

What about the fact that I will display one type of synesthesia only when sleep deprived. This suggests the potential is always there, and only manifests when my brain is stressed. Is this typical, or am I in the 1%? Maybe the 1% figure would be much higher if more people were assessed for sleep-deprived manifestations.

At present it is an open question whether we are all mild synesthetes or if synesthesia is truly a discrete variant of hardwiring. I don’t think Spence’s research has yet settled this question, although it is very interesting – in a very lavendar way.

38 responses so far

38 Responses to “Are We All Synesthetes?”

  1. banyanon 28 May 2009 at 1:32 pm

    Synesthesia is one of those freaky things that really drove me to get my Bachelor’s in Psychology.

    I knew a girl in high school who claimed to see numbers as colors and claimed to be completely consistent with the number/color pairings. She said that if you gave her a completely novel number, something with 6 or 7 digits, she could give you a color for it, and that color would be the same anytime in the future even if she couldn’t remember what she had said the first time. I never tested her, but that seems pretty useful if it would really work. Does that seem plausible to you?

  2. superdaveon 28 May 2009 at 1:38 pm

    In Musicophilia, Oliver Sacks has a really interesting discussion of synethesia, some people with perfect pitch have a different color for every tone.

    I too have mild synethesia when I am sleep deprived. If I am very tired and trying to get to bed, as I drift off to sleep if there happens to be a loud bang or crash I will see a flash of light.

  3. HHCon 28 May 2009 at 1:51 pm

    “Atlthough it is very interesting- in a very lavendar way”. Translation using Russian word meanings for colors would be “although it is very interesting- in a search for wisdom way”.

  4. pecon 28 May 2009 at 2:00 pm

    I see very definite colors for each letter and number. Until I heard about synesthesia I thought everyone saw letters and numbers in color. But I see these “colors” with my mind, not with my eyes. I can see that letters are, usually, black. I could describe exactly what the colors are and they have never changed. They are mixed colors, not simple primary colors.

  5. jbrydleon 28 May 2009 at 2:26 pm

    I’ve never liked the ‘loud colour’ or ‘sharp taste’ distinction. If I say a colour is loud I mean something like “if that shirt were a noise, it would be a loud one.” It’s completely metaphorical, in the same was as I can say “if I were a tree, what tree would I be?” I certainly don’t *hear* a loud noise. There is no qualia. My understanding of synesthesia is that people experience the actual stimulus as if it were real.

  6. MollyNYCon 28 May 2009 at 2:54 pm

    Every time I blinked my eyes or scanned my eyes across different levels of lighting I would hear a distinct “whooshing” sound.

    That’s interesting; when my eyes hurt, I also hear a whooshing sound.

    For years, decades, I thought it was normal–something to do with wearing contact lenses. Then I asked another lens-wearer about the sound. His reply was unintentionally illuminating: “What the hell are you talking about?”

    Is it possible that everyone’s (or most people’s) sensory input has these idiosyncrasies? You experience, say, the color blue or middle C the way you experience it. If it’s accompanied with another sensation, one that’s transitory or otherwise has no practical effect, it might not occur to you that there’s anything unusual about it, let alone that it’s worth describing to someone else.

    (No, Molly. It’s just you.)

  7. tmac57on 28 May 2009 at 3:16 pm

    For a remarkable and extreme case of synesthesia, Read “Born On A Blue Day”, the biography of Daniel Tammet.He was able to memorize the value of Pi to over 22,000 places largely using synesthesia. From Wikipedia:”the detail and specificity of Tammet’s mental imagery of numbers are unusual. In his mind, he says, each integer up to 10,000 has its own unique shape, colour, texture and feel. He can intuitively “see” results of calculations as synaesthetic landscapes without using conscious mental effort, and can “sense” whether a number is prime or composite.”

  8. mdcatonon 28 May 2009 at 3:54 pm

    We are all synesthetes. Case in point, the McDonald-McGurk effect, where the phoneme you hear actually changes in response to visual input (watch this alternately with eyes open and closed – unsettling).

    Speech is processed in a specific way, but the same is plausibly true for all sound and vision. If you think that we experience sound and vision pre-integration, as distinct inputs, then try listening to a periodic rustle in a forest and trying to decide whether the rustling is coming from that squirrel over there, or that quail, or from behind that bush. It’s very different than hearing the sound once you know the object in your visual field that it’s coming from. Sound and visual input are integrated in the dorsolateral prefrontal cortex (DL-PFC), which, interestingly enough, is loaded with HT2A receptors, which agonized by the highly synesthesiagenic molecule LSD. Coincidence?

  9. artfulDon 28 May 2009 at 3:59 pm

    In case you missed it, here’s an article that discusses another book on the subject, Wednesday is Indigo Blue:

  10. dcardanion 28 May 2009 at 5:17 pm

    This has always fascinated me. Like pec, I get certain visual sensations that I associate with other things, but it’s not the same as seeing them. (With me it’s mainly sound that causes the visual sensations, but I used to also have colors for each number and day of the week, though that seems to have waned as I’ve gotten older. I’m also a computer programmer, which I think pec said she was, as well. Wonder if there’s any correlation there?)

    But what’s weird is that when I was in music school, we were taught relative pitch. That is, when hearing two notes either one after the other or at the same time, you would learn to distinguish the interval between them. So you might not know that a C and an E were played, but you could tell that it was a major-third. Our teach would quiz us at the end of every class, and for extra credit, he’d play one or two chords and we had to guess the absolute pitch. I learned the relative pitch as well as other students, but there were a few who clearly had absolute pitch. But one day, he played a root inversion F# Major chord, and I sat bolt upright in my chair. I knew exactly what he was playing for some reason, completely out of context. And it was purple in my mind. I couldn’t do it with any other chord, though (at least not consistently). Only that one for some reason. I don’t know if that counts as synesthesia or not. It seems like it’s somewhere near the border, at least.

  11. sbgon 28 May 2009 at 6:06 pm

    I have time-space/number form synesthesia and only realized it in the past year. I learned to shut up about how I feel time & numbers (or any quantity/sequence) sometime in my 20’s when I realized that not everyone experiences this. I thought that it was a learning disability and still feel that way sometimes.

    Few points.

    First, I think that I read somewhere that the majority of synesthetes (by research reports) experience their synesthetic perceptions in their mind’s eye or that they can tell the difference between the synesthetic ‘hallucination’ and a real perception. Just important to clarify, I think.

    Second, once I had some insight into the multimodal processing, I realized all sorts of things about my synesthesia that I’d never understood before. So I do think that there are synesthetes who just don’t know it because it is so instinctual and they are aware that it is in their mind’s eye and that once you catch on, you may begin to use such internal metaphors to enhance functioning. I think that it can be learned to some degree.

    Third, there are some deficiencies with synesthesia. So while we all may have the ‘ability’ and we have cultural metaphors for some types of synesthesia (e.g., representing time with a clock or calendar) — I believe that Cytowic has reported the prevalence of allochiria and trouble with certain types of maps (which I have both). while we all might have some synesthetic leanings, there is clearly something different about the processing or connectivity within the synesthetic brain.

  12. ianmon 28 May 2009 at 6:15 pm

    “Bouba” is written using rounded characters, while “Kiki” has acute angles everywhere.

  13. artfulDon 28 May 2009 at 6:36 pm

    pec writes: ” I could describe exactly what the colors are and they have never changed. They are mixed colors, not simple primary colors.”
    This suggests you may associate the letters and numbers with the colors used with some methods of teaching the alphabet in pre-school, or maybe homeschool. Like where Aa is shown on a card with a big red apple (and with mixed colors used as well, of course).

    If so, that’s not likely to be a function of synesthesia.

  14. sbgon 28 May 2009 at 6:57 pm

    artfulD writes : “This suggests you may associate the letters and numbers with the colors used with some methods of teaching the alphabet in pre-school, or maybe homeschool. Like where Aa is shown on a card with a big red apple (and with mixed colors used as well, of course).

    If so, that’s not likely to be a function of synesthesia.”

    the synesthetic perception or what we ‘see’ it as is a product of our cognition and experience, as much as any perception is. Our brains are not machines that take in an input and send out an output from day 1. We learn how to perceive and how to cognate our perceptions. This is very clear for the synesthetic experience. All circuits are shaped by experience in everyone’s brain.

    For me, I propriocept time and quantities, anything in sequence and some of my proprioceptive sensations reflect what I understand of time, for example, while others have been strictly adopted from cultural forms. To think that I should’ve been born with this circuitry to produce these sensations just doesn’t make any sense. What pec describes is clearly synesthesia and it might be influenced by his experience in grade school or not.

  15. artfulDon 28 May 2009 at 7:12 pm

    Synesthesia is distinguished by the uncommonness of the phenomena, not the commonality. That was one of the reasons for posting this material to begin with. Read the articles cited by the various posters. Otherwise you are just making up your own definition.

  16. sbgon 28 May 2009 at 7:51 pm


    What is common about seeing colors in your mind’s eye when you see or think of letters?

    For my type of synesthesia, number form, many represent digits 1-12 in a clock-face and then, the numbers take-off in different directions. There is both common and uncommon representation there but it is clearly synesthetic.

    This is detailed in one of the earliest publications on synesthesia by F. Galton (1881). I’ve read quite a bit on the topic.

  17. artfulDon 28 May 2009 at 8:33 pm

    If it’s an experience common to many if not all who learn to read in a certain manner, then it’s not “clearly” as you put it an experience caused by the unique makeup of that individual or otherwise unique to a limited number of people.
    That doesn’t mean you don’t have a type of such, just that pec is not likely to have a rare form of such cognitive perceptivity if rarity is not part of the diagnosis.
    You wrote that “To think that I should’ve been born with this circuitry to produce these sensations just doesn’t make any sense.” And yet you had previously written “there is clearly something different about the processing or connectivity within the synesthetic brain.”
    But maybe you use the word clearly to add color to a phrase rather than meaning. Not at all uncommon.

  18. Sabioon 28 May 2009 at 8:43 pm

    And with the delusion of duality, we often interpret these strange mixing of senses as mystical. I think this is one feed for religious thinking. It has been for me.

  19. CrookedTimberon 28 May 2009 at 11:34 pm

    In his book (A Brief Tour of Human Consciousness), VS Ramachandran offers the hypothesis that synesthesia may be caused by a glitch in the pruning process. Apparently we are born with many more neural connections and then some are pruned away. Sounds plausible. Also, I believe he states that synesthesia is significantly more common in artistic people which may explain some of their talents for metaphor and odd juxtapositions. Not sure how to test his idea though.

  20. eiskrystalon 29 May 2009 at 3:29 am

    So 2 questions that need asking.

    If the more information you have connected to an event helps you remember it, does that mean that synesthetes have better memory and recall.

    and can you train yourself to do it?

  21. TimMillson 29 May 2009 at 4:23 am

    ianm is right – there are other factors in the bouba/kiki thing, specifically to do with the orthographic (written) forms. Experiments are ongoing about what exactly explains this phenomenon (including here at the University of Edinburgh – I was recently at a conference where some work on the bouba/kiki phenomenon was presented). It’s a fascinating behaviour, but it’s definitely a multi-modal thing rather than a synaesthesia thing.

  22. sonicon 29 May 2009 at 5:07 am

    You can train yourself to use memory tricks ala Jerry Lucas. These tricks are similar to synesthesia but may not fit the definition due to the fact the user is using the tricks knowingly and purposefully and can therefore not use the tricks. I’m not sure that fits the definition of synesthesia as discussed.

    Lack of sleep and psychoactive drugs can cause these sensations. Because of that I would think that we all experience synesthesia from time to time. How often and under what conditions would be the variables in that case.

    It is true that drug induce synesthesia can produce vivid memories as well, but it is not a reliable method of memory creation.

    Crooked Timber-
    It is true we are born with more connections. They get trimmed and altered throughout our lives. This is the basic of nueroplasticity.
    “The Mind & The Brain” by Jeffrey Schwartz is an excellent book on this very interesting topic.

  23. cesareon 29 May 2009 at 6:49 am

    there’s a bit of confusion here; it seems here that multisensory processing, synesthesia and synesthetic associations in non synesthetes have been confounded and put all together in the same couldron.

    Synesthesia and synesthetic associations are quite different phenomena and both are instances of multisensory processing.

    Synesthesia is a rare neurocognitive condition in which stimulating a sense modality may elicit automatically an additional experience in another sensory modality.

    Synesthetic associations, on the other hand, are simil-synesthetic phenomena experienced also by non synesthetes. The kiki-bouoba effect, for instance, is considered as an example of synesthetic phenomena in non synesthetes.

    Whereas language-related explanations may account for the kiki-bouba effect, they don’t really seem satisfactory when we move to elementary or meaningless stimuli.

    I work with Prof. Charles Spence and I am the co-author of the paper on synesthetic associations that inspired this discussion. Our claim is (1) that all individuals experience synesthetic associations (2) synethetic associations are cues for combining multisensory information. Note that no linguistic stimuli have been used in our research. If you are interested you can find the original paper here:

  24. Steven Novellaon 29 May 2009 at 8:17 am

    Cesare – thanks for the clarification. The reports that I read did not make the distinction between synesthesia and synesthetic associations clear – in fact some directly conflated them. I am glad to hear that Spence is making this distinction – because that is exactly what bothered me about the reports that I read.

  25. pecon 29 May 2009 at 9:46 am

    [pec writes: ” I could describe exactly what the colors are and they have never changed. They are mixed colors, not simple primary colors.”

    This suggests you may associate the letters and numbers with the colors used with some methods of teaching the alphabet in pre-school, or maybe homeschool. Like where Aa is shown on a card with a big red apple (and with mixed colors used as well, of course).]

    No, the colors used in pre-school are almost always bright primary and secondary colors, not complex mixed colors. Most of my letter and number colors are complex. And my sister has a very different set of colors than I do, and she probably had similar materials in pre-school.

  26. pecon 29 May 2009 at 9:48 am

    “I’m also a computer programmer, which I think pec said she was, as well. Wonder if there’s any correlation there?)”

    I think synesthesia might be helpful in computer programming, since most of the abstract symbols are colored and therefore easier to remember. But I can’t use syntax highlighting!

  27. Gaius Corneliuson 29 May 2009 at 10:52 am

    superdave said: “I too have mild synethesia when I am sleep deprived. If I am very tired and trying to get to bed, as I drift off to sleep if there happens to be a loud bang or crash I will see a flash of light.”

    I get exactly that too, perhaps it is quite common?

  28. pecon 30 May 2009 at 2:54 pm

    And the answer to the question of whether we are all synesthetes is not a simple yes or no, because of course it’s a matter of degree. Not many people have the kind I have, which is clear and definite and constant. I also have very strong emotional preferences for some letters and numbers over others. And I have colored visual-spatial time and date structures.

  29. HHCon 31 May 2009 at 8:19 pm

    cesare, Thank you for your link to your study. I note that you use abstractions for comparisons. If you used human forms would the same methodology work? For example, using a opera singer as a stimulus, would pitch association and size of the human form obtain the same results?

  30. HHCon 31 May 2009 at 8:40 pm

    Continuing along the idea of operatic presentation, I am curious if the pitch and waveform shapes could explain the acceptance of a particular stage set, or if auditory placement of the orchestra impacts the overall appeal of the acoustic musical presentation to an audience.

  31. badrescheron 01 Jun 2009 at 2:58 am

    I have been rather frustrated with much of the literature in the cognitive psy field. Authors often confuse synesthesia with simple associations (such as music with colors), even citing literature about the neurological condition, yet their work is still published.

    I greatly appreciate the way in which you’ve described it here and the comment by cesare.

    A few years ago I saw Ramachandran talk about his work with synesthetes. He has devised tests which distinguish them from normals and rely on what we know about normal processing. For example, if one sees colors when presented with numbers, like the friend banyan described, we could find out by using a simple search task in which a person would demonstrate the pop-out effect Treisman discovered, but only if they were a synesthete.

    The pop-out effect can be shown by a set of trials in which the participant is asked simply to indicate if a target is present as quickly as possible. Reaction Time among conditions is compared. In a simple feature search, such as a blue circle (target) among red circles (distracters), the number of distracters does not affect RT. If the target is present it is easy to see, regardless of how many distracters are present. It is said to “pop out” because it has a feature which is unique.

    If, however, the distracters are both red circles and blue squares, then only the conjunction of two features (circle/blue) distinguish the target from the field. RT becomes a function of the number of distracters – the more distracters, the longer it takes to find the target.

    It is difficult to find a 2 (target) in a field of 5s (distracters). As the number of distracters goes up, RT goes up because the target & distracters are similar. However, if one experiences numbers as colors, a 2 in a field of 5s will pop out, and RT will remain flat regardless of the number of distracters.

    A simple, yet powerful test which cannot be faked. It won’t work for all types of synesthesia, but the most common are things like number/color crosses.

  32. BayAreaGuyon 01 Jun 2009 at 5:38 pm

    I have the strangest type of synesthesia yet. Mine is that I experience numbers and letters as having gender and relationships to one another. People think I’m insane when I tell them that 1 and 2 are an old man and an old woman (respectively), and that their grandson (3) and his best friend (4) hang out together. Forks and knives are male, while spoons are female. Plates are decidedly male, while bowls and glasses are female. This has nothing to do with language, as my native tongue is English, and language that doesn’t assign gender to nouns…but it’s made me wonder whether this tendency is responsible for the languages that do (Italian, Spanish, French, German, etc.).

    Oh, and I had that “eye movement whooshing sound” thing for a few weeks and it drove me mad!! So glad to hear that someone else has experienced it! : )

  33. artfulDon 02 Jun 2009 at 12:33 am

    Don’t look now, but I think your dish just ran away with your spoon.

  34. catgirlon 02 Jun 2009 at 3:15 pm

    Pec, when I read your first comment, I knew exactly what you were talking about. That’s how it happened for me. I was surprised to find out that other people were surprised when I said that 2 is yellow or 5 is grey. I always assumed it was normal and that everyone felt that way. When I read about synesthesia as a teenager, I knew right away that that was the explanation for my experiences. I’m generally glad to have it because it makes arithmetic easier for me to remember. If I think of the wrong answer to a multiplication fact, it just doesn’t feel right. Like you, I don’t actually see written numbers as their colors, and I don’t see auras around them. The numbers appear black but they feel green, white, blue, etc.

    I also see faces in everything, and I wonder if that is related to my synesthesia. I have only met one other person with synesthesia, and he does the same thing.

  35. pecon 03 Jun 2009 at 8:16 pm


    I don’t usually ask people if they see letters and numbers in colors because anyone I asked just looked at me as if I’m strange. And, as I said, I always thought everyone had the same thing. It was less than ten years ago when my sister suddenly found out about it from the internet and she called me and asked what color the number 5 is. I said well of course it’s green, and she said I was nuts — because she thought everyone knew that 5 is pink!

    I think I have a very good memory for phone numbers as a result, and I don’t program my phone with names. I would rather just use my colorful memory.

    And I think it helps with computer programming, as I said before, because you can find and remember things more easily in a program when all the symbols are in color. There is also the spatial aspect which might be helpful — I sort of see and feel the loops and branches swirling around.

  36. Matt S.on 04 Jun 2009 at 5:22 am

    It would be interesting to see this study with control groups for different variables.

    Could the result depend on the language one is brought up in, or is it universal to all humans? What influence has the shape of the letters with which the word is written?

    This research immediately reminded me of onomatopoeia in the Japanese language (which is much more commonly used there). For example “kirakira (キラキラ)” means sparkling, while “botabota (ボタボタ)” is the heavy dripping sound of a liquid. Also interesting in this example, the shape of the letters shouldn’t play a roll, because one isn’t much “sharper” than the other.

    I don’t know a lot about linguistics, but our alphabet is, as far as I known, a visual representation of the phonemes that make up the language. Each letter of our alphabet (or rather the Greek alphabet) represents one phoneme and since it represents a sound, the shape of the letter is reflected in that.

    In comparison the Japanese syllabary (hiragana/katakana) is derived from the Chinese characters (Kanji) which are mainly pictographic or ideographic and do not resemble the sound. This would support the idea that it is not the written representation that influences our choice, but the sound itself.

  37. synesthesia « zooeyon 10 Jul 2009 at 2:21 pm

    […] post I quoted from Ahern’s book, and linked to another interesting blog post on synesthesia, Are we all synesthetes? (Scroll down past the Swedish […]

  38. MrGammaon 26 Aug 2013 at 2:21 pm

    Interesting, I believe you are onto something. Not quite mirror neurons, but yeah, the capacity for all of us in sensing the world of the synesthese. If one person is able then we must all have the capacity for this phenomenon. ASMR is most likely closely related. Here

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