The “global workspace” theory of higher-level human reasoning is the idea that the brain is divided into specialized cognitive modules, which compete to broadcast information in a shared conscious “workspace.” The limited workspace acts as an information bottleneck. This information is then globally broadcasted to be stored in short-term Memory, and actions and perceptions.
From 2022-sfi-embodied-situated-and-grounded-intelligence:
Because different modules can take alternatively take the mic, so to speak, this also pushes cognition toward sequential processing. Further, individual modules must encode their outputs in a way that allows other modules to utilize these outputs. The result is that cognition combines thoughts into a task-appropriate sequence for processing incoming information.
The bottleneck forces sequential processing like that associated with System 2 thinking, which includes conscious reasoning, planning, and imagination.