In American Sign Language, the signs glossed as THAT and as YES also resemble each other. The sign YES is http://www.lifeprint.com/asl101/pages-signs/y/yes.htm

In American Sign Language, the signs glossed as THAT and as YES also resemble each other. The sign YES is http://www.lifeprint.com/asl101/pages-signs/y/yes.htm http://www.lifeprint.com/asl101/pages-signs/y/yes.htm which looks like a head nod, but also it is the general motion your hand takes when you spell Y-E-S in the manual alphabet. (Lots of ASL signs are lexicalized fingerspellings. They started off as just being fingerspelled, but over time they became words themselves) The sign THAT can be used to agree with someone emphatically (and also as backchanneling, as in THAT THAT THAT, is like "yeah, uh huh, oh, ok, mm") For an example see the second image on http://www.lifeprint.com/asl101/pages-signs/t/that.htm http://www.lifeprint.com/asl101/pages-signs/t/that.htm Notice that THAT is made with the Y handshape, same as the initial letter in Y-E-S, and moves like YES. Hmm!