the hidden representation it would kind of become a cat dog maybe you do it 50/50 but then you would also mix the labels of cat and dog 5050 and tell the net well this is a mixture of 50% cut 50% dog and then you would train the network to predict that 50/50 coefficient so they do this the question is at which layer do you do this and they simply I think for each mini batch sample one hidden layer at random they might have someone waiting or something but the way they describe it is they simply sample one layer or mean per mini