The goal here is to describe some of the processes underlying how the auditory, tactual and visual modalities and their combinations convert sensory inputs into two- and three-dimensional objects. Those processes are a mixed bag: some depend on cells tuned to various sensory properties, some depend on rhythmic firing in the nervous system, some depend on our knowledge about the environment and some depend on our expectancies about future events. Those processes are interlocked and interactive, and it amazing to me that those objects emerge so quickly and seamlessly. We can take a...