The problem with perceptrons

But one thing that they couldn't learn was to count the number of objects in a picture. It's… just turned out that that was... because of rather obscure mathematical features of the concept of counting, that a reinforcement neural network of the type that we… many people were interested in just couldn't do that. In order to make a machine that can count, you need a machine that has internal loops inside of circular causality and you can't make a machine that just passes signals from one layer to another, processing them in a kind of linear form. Well, it took us several years to prove that for certain neural networks and… although we published all of this around 1970, there's still some more things to prove about it. And for some reason, nobody has developed... this was a field called perceptrons.