The model of boxes is a good help in explaining some behaviors in terms of the nervous system. Some advantages of the model of boxes are that it can account for

-- autonomy of the nervous system (some outputs do not have to be triggered by anything from the outside of the nervous system.) For example, this model can explain why a person wakes up in the morning happy or sad, if nothing from the outside have caused it. Apparently, something inside of the nervous system is responsible for this.

-- different outputs-responses to the same input-stimulus. The model provides different ways the boxes are connected and it allows to have different outputs for the same input, or no output at all. An example of this phenomena is the person's response to the same song playing over and over again. A person can listen to it for the first time, dance to it for the second time, sing along for the third time, and completely ignore it the forth time.

-- an output reflecting many different inputs. For example, if a person is hungry, he will go and eat. If the person is sick and hungry, he might not feel like eating.

-- parts of the nervous system able to function independently. The model shows that the smaller boxes can receive inputs and outputs independently of the bigger boxes. This also helps me to understand the behavior of the earth worms: as it is known parts of the earth worm separated from the rest of its body are able to move. This illustrates that due to the structure of the worm's nervous system, each part of the worm has sufficient nervous system piece (a small box) that enables it to move without regard to the rest of its body.

-- many other examples

So, as a whole this model is successful in explaining many mechanical concepts of the nervous system and behavior, while it does not help to explain the questions of the mind and personality.

Like your earthworm extension, an apropriate and clear illustration of boxiness. And your advantages in general (though need to be clearer about how this allows for different outputs for the same input). Interesting remaining uncertainty about "mind" and "personality". Because these don't have any "boxy" character to them? PG