Dear All,

It is fascinating how sometimes seemingly totally different aspects of life like engineering, science, human psychology and social behaviour come together as if all have the same underlying cause and structure. Take for example human behaviour, and global optimisation approaches which we use to solve many problems of image processing and computer vision.

In global approaches in order to interpret the data we usually have to minimise a cost function with two terms: the faithfulness to the data term and the model term. I like to call the latter the "prejudice about the world" term. The parameter that balances the two is of such crucial importance, that it effectively dictates the solution. Make that parameter heavy on the side of the model and you can produce any solution you want. Make the parameter heavy on the side of the data and you had it!

For example, have you ever wandered why people quarrel about things that to third parties seem blatantly clear cut? Have you ever come across people who insist on their views even when hard facts are presented to them about the opposite? I find it incredible that two people may read the same facts but come to exactly the opposite conclusions! This is because they use a model-based interpretation of the data. They have to, otherwise the world does not make sense, just like our data with no model are not interpretable. However, in model-based interpretation, one has to remember that the question asked is: "Do the data have a violent objection in being fitted by this model (my pet model)?" Most of the data can be fitted by many models, particularly if we bend them a little. Often the data obligingly answer: "No, I do not mind if you try to fit me with your pet model!" The trouble starts when in the excitement of the success and the narcissism of the "pet-model-fits-wel1" mood, the exact nature of the question is f`orgotten: The pet-model becomes religion, and takes the dimensions of THE model that fitted the facts! Then somebody else comes along with his own prejudices and loaded predispositions expressed by his own pet-model. He sees the same facts, the same data and asks them: "Do you mind if' I fit you with my own pet model my sweetie?" The data are obliging again: "Not at all! Suit yourself!" Put these two ecstatic by their success and foresight people in the same room, and you have a war! Am I exaggerating?

Maria Petrou

PS: Beware of my own prejudicial model of the world!