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 dozen 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 regularly pull out my phone to check a fact, watch a video, read weibo. Such activities fill the spaces that used to be dead time (such as waiting for somebody to arrive for a lunch meeting).

　　But that's the upside (好处). The downside is that in those dead periods I often would let my thoughts flow and sometimes would have an unexpected insight or idea. Those opportunities are now fewer and farther between.

An Extension of the Human Brain A prosthetic nature ●The 　1　can help make up for our mental and emotional deficiencies as a wooden leg can compensate for a bodily deficiency.

●It 　2　in our daily events, extending our intelligence, comprehending our feelings, and expanding the range of social activities.