It's a pretty easy test - they just said "cat food" a bunch of times and ads for cat food came up in their feed the next day. I'm sure if you were interested you could probably do the same experiment with some other product you've never posted about or talked about online and come up with similar results. It seems strange that you would just assume that the people who are bringing up this issue are simply misinformed, or do not also know that facebook also looks at other parts of their data. I think most lay people understand how data mining is leveraged these days.
It's a pretty easy test - they just said "cat food" a bunch of times and ads for cat food came up in their feed the next day. I'm sure if you were interested you could probably do the same experiment with some other product you've never posted about or talked about online and come up with similar results. It seems strange that you would just assume that the people who are bringing up this issue are simply misinformed, or do not also know that facebook also looks at other parts of their data. I think most lay people understand how data mining is leveraged these days.