I find that the various terms currently being bandied about (Larks and Ravens, Jets and Rubies, etc.) create an additional level of confusion for both experienced and new dancers. Not only do you have to process in a split second WHAT to do, you now also have to process which role is yous. If you're going to call dances in which it matters (e.g.,contra dances, rather than beginner-level community dances where it doesn't matter which role is on the right or left), then I prefer Reds and Yellows for R and L terms that relate to the right and left positions. (I know, yellow doesn't START with L, but the double L in the middle serves the purpose). I then use red and yellow wrist-bands as visual cues. Red on the right wrist for the person on the right; yellow on the left wrist for the person on the left. It's cheap and easy to buy a skein of yarn in each color, and cut them up into appropriate lengths. It's then easy to say upfront that if the wrist-bands are next to each other (on your joined hands), you're on the wrong side and need to quickly switch, assuming you want to dance the same role consistently, because switching is much more challenging. I don't have hard data, but my personal experience is that the visual cue makes a BIG difference in response time for all dancers, and there is a higher level of success, and therefore fun.