 hmm oh yes a feature stimulus class I almost said crash I don't know why you know feature stimulus class look at the pretty camera I'm sorry I'm pointing at you but I'm actually looking at a camera you forget right sometimes you just completely forget that I'm actually looking at camera not at you but anyway don't tell anybody so a feature stimulus class is the a particular feature of a given stimulus is going to produce a standard response right you can teach this specifically so if the feature that I was interested in teaching you was blue I would show you an object and say say blue and you would say blue and I'd show you a different object and say say blue and you would say blue and I would show you a different shape of an object and say blue but so I can get you to say all blue in the presence of all sorts of different objects that happen to be blue and then we could generalize that and get you to come talk about the different shades of blue but that's a different issue that's not a feature stimulus class issue so then we can go back and we say oh well now that I've taught you blue we could focus on another feature that we could watch it once you learn about such as the shape square right so I could show you a square that's blue then I'll show you another square that's red another square that's green and it gets you to focus on that particular feature of the stimulus that way whenever you see the stimulus that's a square you say square not blue