Sit in the back of a physics classroom during a final exam, and you'll bear witness to an odd bit of behavior. As soon as the students reach a question about electricity and magnetism, they drop their pencils and stick their right thumbs in the air, with their remaining four fingers curled into their palms. This goes on for a few seconds, and then the hands come down, pick up the pencils and scribble down answers.
Students of physics are certainly passionate, but that's not why they give magnetic fields a thumbs up. The manual display is simply an application of a well-known principle called the "right hand grip rule," a handy trick to determine the direction of a magnetic field produced by electric current in a coil of wire: If the current is traveling around the wire in the direction of your curled up fingers, the magnetic field points in the direction of your thumb.
We humans are often separated from other animals by our ability to use tools. The creative spark in our stone-sharpening ancestors is the same one that churned out combustion engines and Kindles, and our impressive suite of tools is only growing. Tools make our jobs easier and our lives better, allowing us to do superior work more efficiently.
Tools allow us to do more with our hands, but our hands can be tools in their own right. A thumb isn't a prerequisite to study physics, but it helps to have one. For physics students, hands serve as cognitive tools: By applying the right hand grip rule, physicists let their hands do some of the thinking for them, "offloading" their cognition onto their fingers.
The insight should seem intuitive — we use cognitive tools all the time. We don't bother to remember our friends' phone numbers because they're stored in our iPhones; we don't have to perform difficult calculations in our heads when calculators can do them for us. Even the symbolic systems we've developed can be considered cognitive tools — when a friend asks me to write up a column for a magazine, he can tell me exactly how many words he wants in just three characters (7-0-0).
Recently, some clever philosophers of mind have taken this intuitive insight to exciting new places. If physics students really are letting their hands do some of the thinking for them, the argument goes, then maybe our hands are more than mere tools for the mind — maybe our hands are parts of our minds, at least when they're doing the kinds of things minds do. If calculators do the kind of work that would be considered mental if it had gone on inside a skull, and if iPhones store the kind of information that would be considered mental if it had been stored inside a skull, then maybe those devices — and all cognitive tools with them — are themselves stamped with the mark of the mental, and are literally parts of our minds. On this view, then, minds are not confined to skulls: They extend out into the world around us, along bridges we build when we dovetail our minds with our tools.
It remains to be seen whether the "extended mind" thesis, as it is known, turns out to be true. But I think it is at least on the right track. We really do "offload" cognition onto all sorts of tools — call them "cognitive prosthetics." And even if the extended mind thesis is only half-right, the implications are staggering.
I often bring my laptop to class and use the Internet. Sometimes it distracts me, but I think it makes me a better student most of the time. I can look up references mentioned by the professor, clarify something I missed with a quick IM to a fellow laptop-user or, if the class is reviewing something I already know, I can just pick something new to learn online: the day's headlines, an insightful blog post or, if I'm feeling industrious, next week's reading.
That song may sound familiar, and it's been sung before. But if the extended mind thesis is true, there may be a new way to spin it: The Internet is literally a part of our minds.
Our generation bears a unique relationship to the Internet. An older generation might have seen the Internet as an exciting new tool, while for younger generations, the Internet has always been there, fully formed. But our generation has grown up alongside the Internet. The Internet was first put to commercial use in my birth year, 1988, as the ARPANET, what one might call the fetal stage of the modern Internet. I was a late talker, so as I was beginning to expand my vocabulary in 1991, the Internet was finding its voice as well, when it became known as the World Wide Web project. The word "Internet" gained popularity when we entered first grade, and it reached its billionth user around the time when we came to Brown. Each step in our development has been paralleled by a development online.
It's not so surprising then, the kinship we feel with the Internet. It has grown with us, changing to fit our needs. But like any good cognitive tool, it gives as good as it gets, shaping our thinking as well. Even one day without the Internet makes me feel a bit uneasy, like I'm missing a part; and who knows, a week without it could send me into withdrawal. Maybe that makes me an addict. But if the Internet really is part of my mind, is it so strange that I would miss it the way I would any other part of my mental life? The Internet is the cognitive prosthetic par excellence, and that deserves a thumbs up.