Jims review of complexity theory is very nice, and links to the comments I made on Robin's preceding entry.
The "maybe" range may indeed be the best place to look for emerging order. Events are neither unstructured nor so tightly structured that they become rigid. They are in a fluid space of decision possibilities. These possibilities are further specified through interactions between ongoing "intrinsic" states and "extrinsic" events. The teetor-totter is in balance, indecision, potential transition, and so on.
If this "in-between" state could be defined and analyzed more thoroughly, then we would be on our way to understanding many outstanding issues, such as control specificity, local versus global brain/behavior processing, etc.
Obviously, as Jim notes, many human conditions (such as ADHD) might be understood more deeply if we view them as teetor-totter imbalance: either too little structure (diffusion) or too tight a structure (rigidity).
Many neurological disturbances are reflected through often paradoxical issues of a) too much interference through irrelevant channels and b) too little attention to relevant channels. [Of course we have to define what is relevant and irrelevant, not always easy.]
I am not a clinician ("a few of my good friends are"), so I shall have to leave the implications to those with greater expertise than I have. But Jim's evaluation of chaos, etc. does seem to provide a handle that may help bridge the clinical and a broad range of empirical issues.