To express all of our thoughts (and probably some that we will never have), we combine a limited (20,000 to 200,000) words into sentences. The number of possible sentences is unlimited (infinite in number) so we cannot have memorized any but a few stereotypic phrases.
Not any stream of words makes a sentence. The string of words is only meaningful to listener's sharing a set of conventional rules about the structure conveyed by that string of words. (Many strings have more than one structure, hence are ambiguous.)
There are many functions of language; all require that the utterances (movements) express a meaningful idea. Learning speak includes learning the meanings associated with each of the utterances in the language.
Reference is one of the major uses of phrases and sentences -- describing and picking out objects --real, imagined, and abstract. I can essentially "name" or refer to a particular thought I'm having--e.g. the thought that this is a very hot day to be grading 401 exams -- and you all know which thought of mine that I am referring to. While it isn't quite mind reading, it is movment reading.
for the meaningful reference like the above example to work, my description has
to be understood by my listeners and tailored for their consumption --after
all, I already know what my thought is in this case.
Thus the audience and context must be considered in forming the appropriate movement, as well as the content of the thought itself.
Frege's example of difference between morning star and evening star.
Invented sign in young deaf children
What about blind vs sighted children? Surprisingly little differences despite enormous differences in information.
Probably animals can comprehend communication about relationships among objects and themselves -- actions that they engage in. Fetch! Roll over!
"If any of our children learned or used language the way Washoe or Sarah does, we would be terror-stricken and rush them to the nearest neurologist. p373"