Different size needles?

Could someone explain to me about a pattern that uses recycled cotton using a size 6 & 7 circular needle, which is a smaller needle that is recommended for that yarn? I understand about doing a gauge for getting the size correct, but if the needle recommended is larger why is it being recommended to use a smaller needle?
If I am not making sense here let me know…LOL:woot:
Since I have mastered shawls and scarfs I am trying to move on to patterns…

The needle size on the yarn label is not really a recommendation, it’s to show the gauge on a needle so it can be classified into a weight range. Many yarns will say ‘5 sts/in on size 6-9’ to take into consideration that some people will need the larger needle if they knit tight or the smaller one if they loose. But that gauge and needle also depends on how loose or tight the factory knitter made the gauge. However, patterns will often use a different size needle than on the label. The designer of your pattern either wants a really tight gauge or she knits looser and she got the gauge she wanted on smaller needles. You can use a larger needle and see if you get the same gauge, or if it’s for something like a dishcloth, use whatever you’d like.