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

Thinking Machines 105A second selling point, called "graceful degradation," helps deal withnoisy input or hardware failure. Who isn't tempted to throw a shoethrough the computer screen when it responds to the command pritnfile with the error message pritn: command not found? In WoodyAllen's Take the Money and Run, the bank robber Virgil Starkwell isfoiled by his penmanship when the teller asks him why he wrote that heis pointing a gub at her. In a Gary Larson cartoon that adorns the officedoor of many a cognitive psychologist, a pilot flying over a castaway on adesert island reads the message scratched in the sand and shouts into hisradio, "Wait! Wait! . . . Cancel that, I guess it says 'HELF'." Real-lifehumans do better, perhaps because we are fitted with auto-associatorsthat use a preponderance of mutually consistent pieces of information tooverride one unusual piece. "Pritn" would activate the more familiar pattern"print"; "gub" would be warped to "gun," "HELF" to "HELP." Similarly,a computer with a single bad bit on its disk, a smidgen of corrosion inone of its sockets, or a brief dip in its supply of power can lock up andcrash. But a human being who is tired, hung over, or brain-damaged doesnot lock up and crash; usually he or she is slower and less accurate butcan muster an intelligible response.A third advantage is that auto-associators can do a simple version ofthe kind of computation called constraint satisfaction. Many problemsthat humans solve have a chicken-and-egg character. An example fromChapter 1 is that we compute the lightness of a surface from a guessabout its angle and compute the angle of the surface from a guess aboutits lightness, without knowing either for sure beforehand. These problemsabound in perception, language, and common-sense reasoning. AmI looking at a fold or at an edge? Am I hearing the vowel [I] (as in pin) orthe vowel [e] (as in pen) with a southern accent? Was I the victim of anact of malice or an act of stupidity? These ambiguities can sometimes beresolved by choosing the interpretation that is consistent with the greatestnumber of interpretations of other ambiguous events, if they could allbe resolved at once. For example, if one speech sound can be interpretedas either send or sinned, and another as either pen or pin, I can resolvethe uncertainties if I hear one speaker utter both words with the samevowel sound. He must have intended send and pen, I would reason,