I have seen scholars claim that...

"sign languages are simultaneous whereas spoken languages are linear".

In my opinion, however, the notion of "linearity" vs. "simultaneity" is misleading at best.

Sure, the modality of sign languages, the "optical signal", makes it possible to view the articulatory gestures directly, whereas in spoken languages they are mostly invisible and only indirectly "transmitted" through the acoustic channel by means of speech signal.

Yet from the speech signal, by means of a complex bundle of frequency and amplitude information (which is an awful simplification, admittedly), quite a lot of meaningful linguistic information can be extracted simultaneously, such as vowel quality, pitch etc.

When we move on to morphology, we can clearly refer to the many kinds of non-concatenative/nonlinear morphology, such as apophony, be it manifested by tone and/or stress patterns, vowel/consonant gradation etc.

I have also seen people claim that...

spoken languages are 1D (one-dimensional), while sign languages are 3D (spatial).

That, too, seems somewhat strange to propose: apart from the reasons mentioned above, do articulatory gestures not occur in space? True, they cannot be seen, but we could just as well say that the articulatory gestures of sign languages cannot be heard.

I am not a user of a sign language and my knowledge of sign languages is extremely limited, but my impression has been that the options for employing simultaneity may well be considerably wider only thanks to the character of the communication channel, and that the options can be compared, albeit loosely, imperfectly and a bit ad hoc, for example, as follows:

  • laryngeal / jaw angle / velum lowering ~ facial
  • labial ~ left hand
  • bilabiality / labiodentality / protrusion / compression ~ left-hand fingers and their configuration
  • coronal ~ right hand
  • tongue-tip/blade configuration ~ right-hand fingers and their configuration
  • consonants ~ locations
  • consonant transients in vowels ~ movements between locations

And so on... Just like with spoken language we may refer to the notion of tiers and autosegments, even if the feature geometries are largely, if not completely, different.

Would both experts on spoken and sign language agree if I stated that...

spoken languages are articulated internally and thus transmitted indirectly, while sign languages are articulated externally and thus transmitted [more] directly?

It could also be this very directness that would make iconicity easier to employ and, indeed, employ it more widely, transparently and systematically, whereas the indirectness of the spoken languages would make the use of iconicity more constrained and difficult to utilize.

On the other hand, I have also come across an article mentioning something that may, indeed, be unique to sign language, and even truly three-dimensional: spatial deixis. Although it effectively weakens, if not cancels, my anti-3D stance, we can still keep it apart from simultaneity and say that sign languages can employ the external 3D space to express spatial deixis, which spoken languages cannot.

I will be grateful for any relevant suggestions, references or simply comments.


P.S.: I have just discovered the question Simultaneity in natural languages? discusses somewhat similar issues, but, hopefully, mine is still different enough to deserve its existence. :-)

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    Hmm. I agree with you that spoken languages are not strictly linear. However, the fact that we can communicate with writing like this does show that they can be "compressed" to an essentially linear representation without much trouble. The same seems to be basically true for sign languages though, based on what little I know of them. Aug 10, 2015 at 1:09
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    Also, I think most advocates of the idea that sign languages are "simultaneous" or "3D" would agree with you that it's "thanks to the character of the communication channel," but perhaps disagree about the significance. Aug 10, 2015 at 1:10
  • Thank you for your comment, @sumelic. I guess you are right. I am aware of the fact that the specifics of the sign language articulation make it easier to employ, for instance, larger degree of iconicity, especially with respect to size, space and the like. On the other hand, the alphabetical(ish) linearization of the "compressed" signal is, I believe, nothing but a discrete (and, to an extent, artificial) abstraction of a continuous signal composed of partially and fully overlapping events. Aug 10, 2015 at 12:53
  • So, I would simply conclude, perhaps, by saying that the optical channel makes it possible to transmit (and perceive) a larger amount (in a few more tiers, maybe?) of simultaneous information, although I am not sure this would be a satisfactory conclusion to sign language experts. Aug 10, 2015 at 12:56
  • It could be added that the linearity of writing depends largly on the script, orthography, language atc. We do utilize various diacritics to mark suprasegmentals, don't we? Aug 14, 2015 at 22:52

2 Answers 2


Simultaneity just means producing two or three signs simultaneously. It is common in British Sign Language, of which I have a very incomplete knowledge. All you have to do is pick two one-handed signs and add a facial expression (many facial expressions are signs in themselves), and you can easily produce three signs simultaneously, which is like saying three words simultaneously in a spoken language.

Example: raise your left index finger: that can represent a person. Hold it there while pointing at it with your horizontal right index finger. At the same time look at it with a puzzled expression on your face. Literal translation: "Person there puzzling"; natural translation: "That person is puzzling/strange." The left hand, the right hand and the facial expression are three independent signs - independent because each can be done on its own without altering its meaning; and the left hand and the facial expression can both be replaced by a different sign, such as a horizontal flat left hand to denote a car and a facial expression of amazement. Literal translation: "Car there amazing"; natural translation: "That car is amazing!" Simultaneity doesn't happen all the time, but I think it does happen a lot, especially in the form of a facial expression plus one manual sign.

Simultaneity is not mysterious or difficult, but it makes a startling contrast with oral languages that are limited to producing one phoneme at a time in a linear fashion. Hence sign linguists often contrast the simultaneity that comes so easily to sign languages, with the strict linearity of oral languages.


It seems to me that your argument about the simultaneity of articulatory gestures in speech is mostly irrelevant, because the hearer does not perceive these various gestures, but the (single) resulting auditory stream. It is true that in general each such gesture will have an effect on the stream (though in some cases barely detectable) but there is no reason to posit that the hearer reconstructs the articulatory gestures.

In sign language, on the other hand, the simultaneous gestures are directly perceivable, and decomposable.

It is true that vocal speech does not in practice consist of a linear string of independent signals, but that the phones are spread along the speech stream and both overlap in time, and alter one another. It is true also that suprasegmental features can be independent of segmental ones, and thus give a limited degree of parallellism in vocal speech. But this seems very different from the immediately visible (multiple) parallellism and decomposability that is possible with sign language.

  • You couldn't be more wrong. Here is some background on the motor theory of speech perception from Wikipedia: en.wikipedia.org/wiki/Motor_theory_of_speech_perception
    – Greg Lee
    May 18, 2016 at 17:08
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    First, be a little more diplomatic, @GregLee. Second, motor theory of speech perception is not very widely accepted these days. May 18, 2016 at 21:05
  • I wasn't aware of that at all, Greg. I will look at it.
    – Colin Fine
    May 19, 2016 at 7:52

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