From the Phenomenology to the Mechanisms of Consciousness: Integrated Information Theory 3.0
Figure 5
A mechanism generates information only if it has both selective causes and selective effects within the system.
(A) Element A receives input from the system and specifies a selective cause repertoire. However, since it has no outputs to the system it does not specify a selective effect repertoire. (B) Element A receives no input from the system and therefore it does not specify a selective cause repertoire. In both cases the cause-effect information cei generated by mechanism A is zero (the minimum between cause and effect information).