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A first implementation of such a "parallel" activation of nodes might be found in WAIS-style search engines (e.g. Lycos), where one can type in several keywords and the engine selects those documents that contain a maximum of those keywords. E.g. the input of the words "pet" and "disease" might bring up documents that have to do with veterinary science. This only works if the document one is looking for effectively contains the words used as input. However, there might be other documents on the same subject using different words (e.g. "animal" and "illness") to discuss that issue. Here, again, spreading activation may help: documents about pets are normally linked to documents about animals, and so a spread of the activation received by "pet" to "animal" may be sufficient to select the searched-for documents. However, this assumes that the Web would be linked in an intelligent way, with semantically related documents (about "pets" and "animals") also being close in hyperspace. To achieve this we need a learning process.
However, this process would be much more efficient if it could work automatically, without anybody needing to manually create links. It is possible to implement simple algorithms that make the web learn (in real-time) from the paths of linked documents followed by the users. The principle is simply that links followed by many users become "stronger", while links that are rarely used become "weaker". Some simple heuristics can then propose likely candidates for new links, and retain the ones that gather most "strength". The process is illustrated by our "adaptive hypertext experiment", where a web of randomly connected words self-organizes into a semantic network, by learning from the link selections made by its users. If such learning algorithms could be generalized to the Web as a whole, the knowledge existing in the Web could become structured into a giant associative network which continuously adapts to the pattern of its usage.
Imagine the following situation: your dog is continuously licking mirrors. You don't know whether you should worry about that, or whether that is just normal behavior, or perhaps a symptom of some kind of disease. So you try to find more information by entering the keywords "dog", "licking" and "mirror" into a Web search. If there would be a "mirror-licking" syndrome described in the literature about dog diseases, such a search would immediately find the relevant documents. However, that phenomenon may just be an instance of the more general phenomenon that certain animals like to touch glass surfaces. A normal search on the above keywords would never find a description of that phenomenon, but the spread of activation in a semantically structured web would reach "animal" from "dog", "glass" from "mirror" and "touching" from "licking", thus activating documents that contain all three concepts. This example can be easily generalized to the most diverse and bizarre problems. Whether it has to do with how you decorate your house, how you reach a particular place, how you remove stains of a particular chemical, what is the natural history of the Yellowstone region: whatever the problem you have, if some knowledge about the issue exists somewhere, spreading activation should be able to find it.
For the more ill-structured problems, the answer may not come immediately, but be reached after a number of steps. Just like in normal thinking, formulating part of the problem brings up certain associations which may then call up others that make you reformulate the problem in a better way, which leads to a clearer view of the problem and again a more precise description and so on, until you get a satisfactory answer. The web will not only provide straight answers but general feedback that will direct you in your efforts to get closer to the answer.
First, there have already been some experiments in which people steer a cursor on a computer screen simply by thinking about it: their brain waves associated with particular thoughts (such as "up", "down", "left" or "right") are registered by sensors and interpreted by neural network software, which passes its interpretation on to the computer interface in the form of a command, which is then executed. (see also Gregory Kovacs's Neural Interface Project) If such direct brain-computer interfaces would become more sophisticated, it really would suffice that you just think about your dog licking mirrors to see the documents explaining that behavior pop-up on your screen.
Second, the search process itself should not require you to select a number of search engines in different places of the Web. The new technology of net "agents" is based on the idea that you would formulate your problem or question, and that that request would itself travel over the Web, collecting information in different places, and send you back the result once it has explored all promising avenues. The software agent, a small message or script embodying a description of the things you want to know, a list of provisional results, and an address where it can reach you to send back the final solution, would play the role of an "external thought". Your thought would initially form in your own brain, then be translated automatically via a neural interface to an agent or thought in the external brain, continue its development by spreading activation, and come back to your own brain in a much enriched form. With a good enough interface, there should not really be a clear boundary between "internal" and "external" thought processes: the one would flow over naturally and immediately into the other.
Though individual people might refuse answering requests received through the super-brain, no one would want to miss the opportunity to use the unlimited knowledge and intelligence of the super-brain for answering one's own questions. However, normally you cannot continuously receive a service without giving anything in return. People will stop answering your requests if you never answer theirs. Similarly, one could imagine that the intelligent Web would be based on the simple condition that you can use it only if you provide some knowledge in return.
In the end the different brains of users may become so strongly integrated with the Web that the Web would literally become a "brain of brains": a super-brain. Thoughts would run from one user via the Web to another user, from there back to the Web, and so on. Thus, billions of thoughts would run in parallel over the super-brain, creating ever more knowledge in the process.