Suppose the soul has a capacity to develop only one unconscious model at the time. Suppose their is no feedback to the soul regarding the state of the uncoscious model. Suppose the only information the soul got available is the maturity of the brain. We would than have a computer program running through a sequence without any verification. This theory would explain the facts put forth in The Imperial Animal, by Robin Fox and Lionel Tiger.
To make the soul better and more complex one could add a function for verification of the succesful creation of the unconscious model. To make the soul even more complex one could allow several unconscious models to be put in place simultaneously. This way the soul could keep the idea for the unconscious model that has a problem to develop available for a long time before discarding it. This more complex soul would better explain humans development. An even more complex soul might be able to store ideas for the unconscious models and retrieve them when needed. It might be the case that the soul can create ideas for new unconscious models based on the input it gets from the brain. I seriously think my brain need a vacation.