A Distinguishing supervised learning from reinforcement learning in a feedforward model { 1, 1} and t = 1,, T, are projected onto a hiddenlayer h

In order to illustrate the main idea from our paper in a simplified context, we show in this section how observed hidden-layer activity in a linear feedforward network can be used to infer the learning rule that is used to train the network. Consider the simple feedforward network shown in Fig. S1. N (0, Σ) is noise injected into the network. This is similar to learning with Feedback Alignment [4], except that here we do not assume that the readout weights are being learned. Equations (11) and (13) provide predictions for how the hidden-layer activity is expected to evolve under either SL or RL.