The method was called 'empowerment'. Two ways to explain it...
From a mathematical perspective, we used Information Theory to model the world as an information theoretic 'loop'. The agent could 'send' a signal to the world by performing an action, which would change the state of the world; the state of the world was what the agent 'received'. This obviously relies on having a model of the world and what your actions will do, but doesn't burden the model with other biases.
Pore more colloquially, the agent could perform actions in the world, and see the resulting state of the world (in my case, that was the location of the agent and of the ghosts). Part of the principle was that changes you cannot observe are not useful to you.
From a mathematical perspective, we used Information Theory to model the world as an information theoretic 'loop'. The agent could 'send' a signal to the world by performing an action, which would change the state of the world; the state of the world was what the agent 'received'. This obviously relies on having a model of the world and what your actions will do, but doesn't burden the model with other biases.
Pore more colloquially, the agent could perform actions in the world, and see the resulting state of the world (in my case, that was the location of the agent and of the ghosts). Part of the principle was that changes you cannot observe are not useful to you.