Let's spend a few more minutes on our hidden agenda of the link between search and the mind before we return to technology and algorithms. So page rank as we've seen is quite intuitive and we rely on it more and more. How does this behaviour of ours affect the accuracy of page rank? Does page rank get better because we use it more and more to search? Does it get worse? Or are these two things completely unrelated? Let's think about it in this way. Page rank relies on hyperlinks between web pages. Well, why should we include hyperlinks in our web pages when it's easier to just Google anything? Increasingly, more and more people are putting fewer and fewer hyperlinks in the new material that they put up. This is bad for page ranks. Since we have fewer hyperlinks in the web, the accuracy of page rank gets worse and worse. The more we use page rank, the less we put in hyperlinks and the more inaccurate page rank will get. Now let's ask the reverse question. We find it hard to remember facts, so we increasingly use Google. How does this affect our ability to remember things? It's generally believed that our memories rely on building associations between words, incidents, facts. Each of these being strengthened every time we duress them during acts of recall. In this case, the more we use Google to remember things, the less we can remember, because we don't traverse our associations as much as we did before. This is actually the argument made by Nicholas Carr in his 2010 book, The Shallows, what the internet is doing to our brains. But, is there a positive side to the story as well? Let's talk about Google first. Mere indexing based on words and their occurrence in documents is quite poor at capturing deeper associations between documents, words and concepts. However, when we search and retrieve documents, we also divulge information on the relative relevance of the search results in comparison to our query. So for example, if we click on document which page rank returns to us, we are revealing that we are actually interested in that particular result as opposed to others. Exploiting such relevance feedback. From users. Can actually improve search. And be used to augment, page rank itself. So our use of search itself can be used to improve search. Even while page rank's original avatar might get less and less relevant as we use fewer and fewer hyper-links. But what about us and our memories. Well, exercising recall abilities is not the only time connections are built between synapses in our brain. We use and create fresh connections when reasoning about things as well. But reasoning relies on a lot of facts. And Google provides these facts abundantly and easily. Encouraging more reasoning, and so building more and probably deeper associations. Just think how much easier research has become when we can recall facts from Google, rather than relying on our own memories. Well we shall soon return to technology and search. But hopefully this diversion into our hidden agenda will spark some interesting discussions on the forum. I'm looking forward to it.