【AnExtensionoftheHumanBrainOtherpeoplecanhelpuscompensateforourmentalandemotionaldeficiencies（欠缺），muchasawoodenlegcancompensateforaphysicaldeficiency．Tobeexact，otherpeoplecanextendourintelligenceandhelp】

　　An Extension of the Human BrainOther people can help us compensate for our mental andemotional deficiencies （欠缺），much as a wooden leg can compensate for a physical deficiency．To be exact，other people can extend our intelligence and help us understand and adjust our emotions．When another person helps us in such ways，he or she is participating in what I've called a"social prosthetic （义肢的）system．"Such systems do not need to operate face-to-face，and it's clear to me that the Internet is expanding the range of my own social prosthetic systems．It's already a big bank of many minds．Even in its current state，the Internet has extended my memory and judgment．

　　Regarding memory：Once I look up something on the Internet，I don't need to keep all the details for future use-I know where to find that information again and can quickly and easily do so．More generally，the Internet functions as if it were my memory．This function of the Internet is particularly striking when I'm writing； I'm no longer comfortable writing if I'm not connected to the Internet．It's become natural to check facts as I write，taking a minute or two to dip into PubMed，Wikipedia，or other websites．

　　Regarding judgment：The Internet has made me smarter in matters small and large．For example，when I'm writing a textbook，it has become second nature to check a dzen definitions of a key term，which helps me dig into the core and understand its meaning．But more than that，I now regularly compare my views with those of many others．If I have a"new idea，"I now quickly look to see whether somebody else has already thought of it，or something similar-and I then compare what I think with what others have thought．This certainly makes my own views clearer．Moreover，I can find out whether my reactions to an event are reasonable enough by reading about those of others on the Internet．

　　These effects of the Internet have become even more striking since I've begun using a smartphone．I now