In various situations, sign language is used spontaneously by HEARING-ABLE people, e.g.
Drivers in vehicles signalling to each other. The only research into sign language I have been able to find 'on the NET' relates specifically to 'deaf' people. How/where would I find discussions about the other type - it would EX-clude 'Morse flag waving' and pennant flying, as these are not SPONTANEOUS.