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Steven Pinker -- How the Mind Works - Hampshire High Italian ...

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Thinking Machines 103do it. Mechanically speaking, <strong>the</strong> more clue units <strong>the</strong>re are that areturned on, <strong>the</strong> greater <strong>the</strong> activation of <strong>the</strong> conclusion unit. We couldimplement different statistical procedures in <strong>the</strong> network by designing<strong>the</strong> conclusion unit to integrate its inputs in different ways. For example,<strong>the</strong> conclusion unit could be a threshold unit like <strong>the</strong> ones in crisp logicgates; that would implement a policy to put out a decision only if <strong>the</strong>weight of evidence exceeded a critical value (say, "beyond a reasonabledoubt"). Or <strong>the</strong> conclusion unit could increase its activity gradually; itsdegree of confidence could increase slowly with <strong>the</strong> first clues tricklingin, build quickly as more and more are amassed, and level off at a pointof diminishing returns. These are two of <strong>the</strong> kinds of unit that neuralnetworkmodelers like to use.We can get even more adventurous, and take inspiration from <strong>the</strong> factthat with neurons, unlike silicon chips, connections are cheap. Why notconnect every unit to every o<strong>the</strong>r unit? Such a network would embodynot only <strong>the</strong> knowledge that greenness predicts vegetablehood andcrunchiness predicts vegetablehood, but that greenness predicts crunchiness,crunchiness predicts leafiness, greenness predicts lack of mobility,and so on:

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