That is to say, if the arrow between Orient and Act were removed altogether, the diagram would make more sense to me. Alternatively, if Orientation is sometimes a kind of Act, then the looping could be something like:

Observe — Orient/Act — External World
…
……
…..Orient — Decide — Act — External World
…………………..
…………………….
…………………..Observe

The Orient-Act link (called “implicit guidance and control” [1] ) is the hardest part of the OODA loop to get. My first post on 5GW,for instance, contained a misleading depiction of the OODA loop [2] that I later corrected [3]. To quote myself from that article

“That is, the flow from Observe to Act is the primary link out of Observe. Most actions are not “decided” upon, so the Observe-Decide flow is a secondary link.”

Or to quote Chet Richards [4]

“In a real-time operation, the “Implicit guidance and control” link from Orientation to Action should control, most of the time (95-99%). Important to recognize, though that this is not a reflex, not a direct Observation – Action link. It goes through Orientation, which is where previous experience and intuitive analyses/synthesis come into play.

The key to the Decision box is the subtitle, “Hypothesis.” The Decision block is the learning phase, where you try things out and learn from the result. It is part of how the loop shapes future Orientation. What you learn becomes a part of your (previous) experiences as well as affecting the types of analyses and syntheses you are able to perform. It is still operating even in the middle of a fight, although at a reduced level, since you will learn somethings about your opponent in the contest. However, it is most active in training, where you can try new things and learn without getting killed. All the hours of training that the martial artists go through is to program their Orientations so that the vast majority of the time, effective actions flow smoothly and rapidly from Orientation. A formal decision mechanism would be too slow. In fact, one thing you would like to do is force your opponent to make explicit decisions, i.e., force him out of what he can handle intuitively. Operating inside his/her OODA loops is one way to do just that.”

I hope this helps.

I saw the little arrows going down in the email notification of your comment, so I'm not sure why they're not displaying other than a blogspirit bug.

[1] http://www.mindsim.com/MindSim/Corporate/OODA.html
[2] http://www.tdaxp.com/archive/2005/07/18/go-deep-ooda-and-the-rainbow-of-generational-warfare.html
[3] http://www.tdaxp.com/archive/2005/07/20/ooda-loop-as-flowchart-try-2.html
[4] http://www.tdaxp.com/archive/2006/02/08/chet-richards-on-formlessness-and-orientation.html#c545319

I also read that Slashdot [1] article on rat memory. I got your comment while I was finishing up the second part of this series, which used another study of rodents as part of its argument.

Interesting comment “fired in reverse order as if to etch the memory.” PISRR is something like OODA in reverse order.

I'm not sure if rats can reason enough to “decide,” but I'm pretty sure slime mold can't [2]. Then again, what about a purely logical predator… [3]

Coast to Coast AM had a guest [4] on this recently that's worth checking out, if you're a subscriber.

[1] http://science.slashdot.org/article.pl?sid=06/02/13/0614258
[2] http://www.newscientist.com/article.ns?id=dn8718
[3] http://www.newscientist.com/article.ns?id=mg18324642.800
[4] http://www.coasttocoastam.com/shows/2006/02/05.html