Random variation is added to all weights.
The use of this explicit sensor-direction coupling creates a successful learning paradigm. In the beginning, the blank player will promptly suicide by crashing blindly into a nearby wall. But after some 20 games it will be able to play a good game against a human or a different artificial Tron player. This scenario leaves us however with the feeling that almost all that was to be learned was really known from the beginning. All the algorithm has done is adjusting the parameters to an equilibrium value.