A group of cloaked smugglers and thieves use an unspoken language of hand signals, like ASL. However, I was imagining they use finger digits, the position of the thumb, and the rotation of the hand instead of hand motions (that may require whole arm movements), though this is just an idea; I'm open to others.

The goal is to make the signals as quick as possible and with as little effort as possible, so that if they get in tight situations they can communicate efficiently. Under these constraints, what are the bare minimum concepts required for adequately communicating? By this I mean either having very few things that one is able to say in the language (and therefore my question is what would those be), or possibly having a set of very vague and very precise concepts that work together (and therefore what would those be).

Because the signals are just a combination of finger positions it could be easy to mix up signs and misunderstand. Depending on the answer to the first question, there may be enough concepts assigned to each finger combination that misunderstandings would be caused. If this is true, what should be changed in order to quickly, with little movement, convey the same ideas?

  • $\begingroup$ Aren't there real systems like that? Also look at other improvised communication systems like "tap codes" used by prisoners. $\endgroup$ – JDługosz Jun 1 '15 at 1:16
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    $\begingroup$ I don't think what you're looking for is a full-fledged language. If they're just using it during their robberies, you can probably get away with a few hundred "words" carefully chosen, compared to the thousands used for proper everyday communication. $\endgroup$ – evankh Jun 1 '15 at 1:28
  • $\begingroup$ @JDługosz I am unaware of real systems like this. Could you list some? $\endgroup$ – Towell Jun 1 '15 at 1:29
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    $\begingroup$ TV portrails of military operations always show sign language. If that is real, I would think that it's close to what you want. It would be contextual because they know the plan and contingencies, and could "spell out" specific words (slowly) if necessary. I recall the real survivors of The Great Escape explaining the use of a "knock code" to track guard movements and otherwise communicate to the hidden wokers. $\endgroup$ – JDługosz Jun 1 '15 at 1:35
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    $\begingroup$ I don't know how accurate TV shows like Stargate SG-1 are in portraying it, but there is a standard set of military hand signals, for example here: i.imgur.com/0NDiIPd.jpg $\endgroup$ – Caleb Hines Jun 1 '15 at 4:16

Have you ever heard someone speak Spanish or Chinese? To an English speaker, Chinese sounds slow and Spanish sounds fast. This is due to something that I will refer to as the information density of a language (ID). This is how much information is in a syllable or motion in the language. Spanish has a low information density. This leads to an observation: ID × rate of speech/motion = c. The value c is a constant. This is why Spanish is spoken quickly. Chinese has a high information density. Each word has very few syllables, and each word denotes its own object (i.e. Chinese has no the's, a's, or an's, etc.). This is why Chinese sounds slow to English speakers. Spanish has low information density because of all the el's and la's. (English's ID is lower due to the's and a's and an's) Because c is constant, making the language quick is hard. The constant c is not a limitation of our tongues or hands but rather our minds. If your robbers where all geniuses, c might be higher for them. Also, we could try assigning an extremely high information density. Raising your hand could mean something arbitrarily specific, such as "Jim walked by the meadow during the Summertime." Such a specific, informationaly dense language would not be practical, but it could work as a code only for the robbery and not for everyday life. In that case, the above equation does not apply.

Here is some more information on ID.

  • $\begingroup$ Could you go a little further in depth about information density, with examples? $\endgroup$ – Towell Jun 1 '15 at 0:18
  • $\begingroup$ @XosMel I will add more examples. $\endgroup$ – Jimmy360 Jun 1 '15 at 0:20
  • $\begingroup$ The link provided expands your explaination some, but it does not help me create a language. Do you know more about how to pack information into a syllable? $\endgroup$ – Towell Jun 1 '15 at 1:36
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    $\begingroup$ @XosMel However, you should just use a code to get around the dreaded constant c. $\endgroup$ – Jimmy360 Jun 1 '15 at 3:11
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    $\begingroup$ Also recall that language is a compromise between information density and information redundancy. The redundancy allows you to figure out the meaning if bits of the information are lost in the conversation. Languages with higher information content are more likely to induce misunderstandings, especially in places that make it hard to hear. $\endgroup$ – Jim2B Jun 1 '15 at 3:30

Because you need it for thieves, and only for emergency situations like when they are on a job and need to be quick about it, I don't think you need a 'full' language.

I would make it so that to communicate they need to put their hand(s) in a certain spot, like in front of your chest or something. This way you will always understand the 'up' and 'down' of a certain sign. Less chance to get confused.

I would also make the signs stand for commands or ideas instead of words. For example instead of 'speaking' in the sign language that a thief is going to do x, a thief could just use a single sign that stands for x. I reckon that there are only so much things they need to be able to communicate in the heat of a job/ battle.

Things that spring to my mind are basic military signs like 'halt', 'march', 'covering fire' and such; and more job specific things like 'Guard the way out' or 'Rendezvous here in n minutes'


There are three ways to go with inventing a language, signed or otherwise:

  • Sign = letter/sound. The English alphabet captures most sounds as a single character. To make a word, the sounds are strung together; a single word will have lots of characters. In ASL, it's possible to spell any words using finger spelling, but it's quite slow. Also, a direct correlation between an alphabet and a hand sign could be fairly easy to spot and decipher. On the positive side, any word could be communicated, and there are only 26 signs (assuming they mirror the English alphabet) to memorize, and it would only take a single hand to communicate.
  • Sign = word. ASL, for the most part, uses a single sign for each word. It also leaves out words; articles (the, a, etc), many prepositions, any other "low information" words are left out. That makes signing in ASL fairly fast. However, there are a lot of signs to memorize, and new signs will need to be invented for new words. Plus, many signs in ASL are two handed.
  • Sign = phrase. If there are fairly few phrases, a single sign can be used as a whole phrase, especially if different fingers man different words: index finger raised means Alice, halfway up means Bob, and down means both; pinky up means go forward, pinky halfway up means left, down means right. Essentially, each finger position becomes a trinary bit (or binary, for up/down only). Many complex phrases could be boiled down to a single, easy-to-learn sign. Of course, it would be difficult to have a real conversation, but perhaps a secondary method of communication could be used for that.

For covert communication, signed "hytes" (hand bytes) would not only be easy to learn quickly, but could be expanded to include written signs, too. A hand sign, from thumb to pinky, for example, may be up-up-down-up-down. It could also be written !!.!. or 11010.

A single hand, using two-position fingers, would communicate up to 32 different signs. Using three-position signs results in 243 signs! Adding hand up/down/sideways and facing/reversed multiplies the total by six.

Obviously, other methods of "count-signing" could be used, like joint counting, pointing at various locations (ear, nose, etc.), or even tapping, or a combination of all of the above.


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