Mind Out


Sounds 1-6, Patrick Hartigan, 2006. Via

From The New York Review of Books:

Kurzweil has honors from three US presidents (so says Wikipedia) and was the “principal inventor of the first CCD flatbed scanner” and other useful devices, as well as receiving many other entrepreneurial awards. He is clearly a man of many parts—but is ultimate theoretician of the mind one of them? What is this grand theory? It is set out in chapter 3 of the book, “A Model of the Neocortex: The Pattern Recognition Theory of Mind.” One cannot help noting immediately that the theory echoes Kurzweil’s professional achievements as an inventor of word recognition machines: the “secret of human thought” is pattern recognition, as it is implemented in the hardware of the brain. To create a mind therefore we need to create a machine that recognizes patterns, such as letters and words. Calling this the PRTM (pattern recognition theory of mind), Kurzweil outlines what his theory amounts to by reference to the neural architecture of the neocortex, the wrinkled thin outer layer of the brain.

According to him, there are about 300 million neural pattern recognizers in the neocortex, with a distinctive arrangement of dendrites and axons (the tiny fibers that link one neuron to another). A stimulus is presented, say, the letter “A,” and these little brain machines respond by breaking it down into its geometric constituents, which are then processed: thus “A” is analyzed into a horizontal bar and two angled lines meeting at a point. By recognizing each constituent separately, the neural machine can combine them and finally recognize that the stimulus is an instance of the letter “A.” It can then use this information to combine with other letter recognizers to recognize, say, the word “APPLE.” This procedure is said to be “hierarchical,” meaning that it proceeds by part-whole analysis: from elementary shapes, to letters, to words, to sentences. To recognize the whole pattern you first have to recognize the parts.

The process of recognition, which involves the firing of neurons in response to stimuli from the world, will typically include weightings of various features, as well as a lowering of response thresholds for probable constituents of the pattern. Thus some features will be more important than others to the recognizer, while the probability of recognizing a presented shape as an “E” will be higher if it occurs after “APPL.”

These recognizers will therefore be “intelligent,” able to anticipate and correct for poverty and distortion in the stimulus. This process mirrors our human ability to recognize a face, say, when in shadow or partially occluded or drawn in caricature. Kurzweil contends that such pattern recognizers are uniform across the brain, so that all regions of the neocortex work in basically the same manner. This is why, he thinks, the brain exhibits plasticity: one part can take over the job performed by another part because all parts work according to the same principles.

It is this uniformity of anatomy and function that emboldens him to claim that he has a quite general theory of the mind, since pattern recognition is held to be the essence of mind and all pattern recognition is implemented by the same basic neural mechanisms. And since we can duplicate these mechanisms in a machine, there is nothing to prevent us from creating an artificial mind—we just need to install the right pattern recognizers (which Kurzweil can manufacture for a price). The “secret of thought” is therefore mechanical pattern recognition, with hierarchical structure and suitable weightings for constituent features. All is revealed!