I nearly posted exactly this, but was wondering if a single instance of a thing [I read about cats and then saw an ad about cats] would be enough to qualify. I

I nearly posted exactly this, but was wondering if a single instance of a thing [I read about cats and then saw an ad about cats] would be enough to qualify. I agree that it does sound like a subjective bias and would need to know how many ads are seen that don't ring the bell.