ear training and octaves

Not sure if this goes in music theory or beginners, but I'm working on ear training at the minute and wondering if anyone else has had the same experience. I have difficulty identifying octaves, and I get the impression it should be easy, but all I really notice about them is that I don't notice anything about them. Or, to put it another way, given an interval I currently have to identify octaves by process of elimination. I'm hoping that this is an early learning curve thing and it'll sink in eventually, but in the meantime it'd be interesting to know whether other people find octaves easy.