A neural network, whether software-based, hardware-based, or wet-ware based (rat in this case, or human for that matter), can only spot patterns in a given set of data which are there. No patterns in the data means no predictability. You can have the coolest, most hyper-intelligent system ever devised, but that cannot see patterns which do not exist. Of course market data has patterns (sell on Friday, for instance), but it is always limited. Generally, I think you could even in principle never get more than 80% accuracy with any kind of neural network, because of the lack of complete patterns in market data, whether we are talking about a rat or a human or a whatever kind of neural network. Which brings me to a second point, since 100% accuracy or anywhere near that is not possible even in principle, applying electric shocks to test subjects when they are wrong is simply cruel and irresponsible.